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1|Page SAQIB IMRAN 0341-7549889 1 2|Page Estimation Rate Analysis | Factors affecting rate of an item Rate analysis : Rate analysis is the study of principal role played by various constituents, elements of construction such as equipments, cost of labor, number of equipments etc. Rate of an item = Cost of material (A) + Cost of Labor (B) + Cost of scaffolding (C)+ Cost of water charges (D) + Cost of sundries (E)* Sundries mean cost of all small items which cannot be accounted separately. Factors affecting rate of an item : 1. 2. 3. 4. 5. Locality and situation. Size and extent of work. Nature of project. Height/Level of work at which it is being executed. Environmental and climatic conditions. Critical path method | CPM Logic Network Critical path method (CPM) CPM is a project scheduling method where activities are arranged based on interrelationships and the longest time path through the network called the critical path is determined. The critical path method focuses the relationship between the critical activities. It is an activity relationship representation of the project. Critical tasks which control the project duration are determined. Because of the size and complexity of major construction projects, the CPM is most often applied using a computer software program. The CPM calls attention to which activities must be completed before other activities can begin. SAQIB IMRAN 0341-7549889 2 3|Page CPM calculation define a time window within which an activity can be performed without delaying the project. Requirements of Using CPM Using the CPM to develop a schedule requires detailed investigation into all identifiable tasks that makeup a project. This means that manager must visualize the project from start to finish, and must estimate time and resource requirements of each task. It is good practice to also obtain information from superintendents and sub-contractors. CPM Logic Network of Logic Diagram The most important feature of the CPM is the logic diagram. The logic diagram graphically portrays the relationship between project activities. With this, it is easier to plan, schedule, and control the project. Reduces the risk of overlooking essential tasks and provide a blueprint for long-range planning and coordination of the project. Generates information about the project so that the manager can make timely decisions if complications develop during the progression of work. Enable the manager to easily determine what resources are needed to accomplish the project. Allows the manager to determine what additional resources will be needed if the project must be completed earlier than originally planned. Critical path and critical activities The critical path through a schedule network is the longest time duration path through the network. It establishes the minimum overall project time duration. All activities on the critical path are critical activities. A critical activity may be determined by applying either of following rules : the early start and the late start times for a particular activity are the same. the early finish and late finish times for a particular activity are the same. Calculation of Forward Pass | Early start/Early finish time Forward Pass Forward pass is a schedule calculation that determines the earliest start and early finish time of the activities and the minimum project duration. SAQIB IMRAN 0341-7549889 3 4|Page A forward pass through the logic network will yield this information: The earliest time each activity in the network can start and finish. The minimum overall duration of the project. In performing forward pass calculation, all successor activities are started as early as possible. And Each activity is postulated to finish as soon as possible. This finish requirement yields the following equation: Early finish of nth activity = Early start of nth activity + Duration of nth activity Early start/Early finish time Early start time (ES) of an activity is the earliest point in time, that an activity may start. The starting point for performing a forward pass is the first activity in the network. In the case of first activity of the project, the earliest time they may start is zero ( the end of day 0 or beginning of day 1). Calculation of early start/early finish If only one precedence arrow leads into an activity, then that activity’s early start time is the same as the previous activity’s early finish time. It means the early start time of the next activity will be the same as that of the early finish of the previous activity. To determine the early start time, when more than one arrow leads in to its node. Select the largest early finish time of all activities at the tail of arrows. Logically, an activity cannot be start until all previous activities are completed. In this case, the equation of early start will be: Early start of nth activity = Maximum early finish of all previous activities Early finish time The early finish time is the earliest time the activity may finish. Add the duration of each activity to the early start time to compute early finish time. Using this systematic procedure, compute all the early start and early finish times from the beginning activities to the finish of the project. This sequence will complete the forward pass. SAQIB IMRAN 0341-7549889 4 5|Page Overall duration of the project The overall duration of the project is the Early Finish (EF) of the last activity in the network. Calculation of backward pass | Late start/Late finish time Backward pass Backward pass is a schedule calculation that determines the late start and late finish times of the activities under the condition that the project’s minimum duration be maintained. A backward computational sequence through the logic network will produce the last point in time that each network activity can start and finish, and still maintain the minimum overall project duration. Calculation of backward pass The backward pass calculation starts with the last activity in the network. This last activity is assigned a late finish time equal to its early finish time as calculated by the forward pass. Late finish/Late start The late finish time of an activity is the last point in time that an activity may be finish. To calculate late finish time and late start time of an activity, follow the precedence arrows backward through the logic diagram. The late finish time of an activity is the latest point in time, that an activity may be finish without delaying the project. Calculation of Late start/Late finish To compute the late start time of an activity we have to subtract the activity’s duration from its late finish time. The late start time is the latest time the activity may start without delaying the entire project. SAQIB IMRAN 0341-7549889 5 6|Page Late start (LS) = Late Finish ( LF) – Duration The preceding activity’s late finish time is the succeeding activity’s late start time. To determine the activity’s late finish time when more than one arrow tail leads away from its node, choose the smallest late start time of all the activities at the arrow’s heads. Logically an activity must be finish before all following activities may begin. Using this backward systematic process, work through the entire logic diagram against the arrows. Compute all the late finish and late start times. This movement back through the logic diagram is known as backward pass. The late start time of the first activity must be zero. Float | Total Float | Free and Interfering float Float Float is an additional time available to complete an activity beyond the activity’s work duration. For example having 6 days available to do 4 days worth of work. Activities on the critical path have no float. Total Float Total float is the amount of time that an activity can be delayed without delaying the project’s estimated completion time. Total float assumes that all preceding activities are finished as early as possible. All succeeding activities are started as late as possible. Total float for an activity can be determined either : Total float activity n = Late start activity n – Early start activity n Total float activity n = Late finish activity n – Early finish activity n Where n denotes the nth activity. Both equation will yield the same answer. SAQIB IMRAN 0341-7549889 6 7|Page Free float Free float is the duration of time, that an activity can be delayed without delaying the project’s estimated completion time and without delaying the start of any succeeding activity. Free float is the property of an activity not a network path. Free float can be determined by : Free float n = Minimum early start of all successor activities – Early finish n Where n denotes the nth activity. Interfering float Interfering float is the time available to delay an activity without delaying the project’s estimated completion time, but delaying an activity into interfering float will delay the start of one or more following non-critical activities. Interfering float n = late finish n – Smallest early start of succeeding activity The aggregate of free float and interfering float is equal to the total float. Total float n = Free float n + interfering float n Type of Construction contract | Lump sum contract Lump sum contract Lump sum contract is typically used in building construction projects in which quantities are exactly measured. Typically used with Design-Bid-Build method of project procurement. A lump sum contract, sometimes called stipulated sum, is the most basic form of agreement between a supplier of services and a customer. The contractor agrees to provide specified services for a specific price. The customer agrees to pay the price upon completion of the work. Or the customer will pay according the schedule of payment. In developing a lump sum bid, the builder will estimate the costs of labor and materials. Then add to it a standard amount of overhead and a normal amount of profit. SAQIB IMRAN 0341-7549889 7 8|Page Most of the builders add their profit 12%-16% of the total project cost. This amount of profit may be enhanced according to builder assessment of risk. If the actual cost of the project increases than the estimated amount, then builder’s profit will be reduced. If the actual costs decreases, the builder gets more profit. The cost to the owner will be the same in both cases. But In actual practice, the costs that exceed the estimated amount, results in the disputes between the client and the builder. Or the builder will use the low grade materials to complete the work in the same profit. The lump sum contract may contain a section that contains unit price of items. Unit Price is often used for those items that have indefinite quantities, such as pier depth. A fixed price is established for each unit of work. Following are some of the features of the lump sum contract. Builder is free to use any resources and processes to complete work. Contractor or builder is responsible for proper work performance. Work must be very well defined at bid time.. Owner’s financial risk should be low and fixed at outset. Builder has greater chances of more profit. Requirements of lump sum contract Good project definition is required for lump sum contract. Lump sum contract requires complete plans and specifications setting and directions in enough detail to enable a contractor to carry them out. Stable project conditions are necessary. Effective competition is necessary when bidding. There should be much longer time to bid and to award lump sum type of project. Advantages of lump sum contract Low financial risk to Owner. High financial risk to Contractor. Know cost at outset. Minimum Owner supervision related to quality and schedule. Contractor should assign best personnel due to maximum financial motivation to achieve early completion and superior performance. Contractor selection is relatively easy. Disadvantages of lump sum contract Changes in lump sum contract are difficult and costly. Early project start is not possible because of need to complete design before bidding. Contractor is free to choose lowest cost means, methods, and materials consistent with the specifications. Only minimum specifications will be provided. SAQIB IMRAN 0341-7549889 8 9|Page If the owner is not able to write the desired specification, then he should expect that the contractor will use the lowest suitable grade materials. This will increase the profit of the contractor. Hard to build relationship. Each lump sum project is unique. Bidding is expensive and lengthy in lump sum contract. Contractor may include high uncertainty within each Schedule of Value item. Definition of Estimate | Estimation | Need for an estimate Estimate An estimate is an anticipated or probable amount of construction which is usually made beforethe execution of the actual construction work. Estimation Estimation is the scientific way of working out the appropriate amount of engineering project prior to the execution of work. It is important to note that estimated amount may be different from the actual cost of the project. Estimated amount should not be differ than 5% to 10% of the actual cost of the project. Estimation requires thorough knowledge of construction procedure, labor and material. It requires knowledge of drawing specifications and prevailing market rates. Need for an estimate The main purpose of an estimate is to know the probable amount before the work is executed. The actual cost is always obtained after the completion of project. If the estimate is carried out with lot of accuracy. Then the actual cost will be near to the estimated amount. That is the reason why experienced person is employed for this purpose. Estimate of a project will help us in following ways. It tells whether the project is suitable or not by considering the cost comparison. The quantity of major components of the project like cement, bricks, steel, sand etc and their cost to be entered by considering the prevailing market rates. It helps to invite tenders. It helps to monitor the contractor payment record. We can also check the contractor work being executed. SAQIB IMRAN 0341-7549889 9 10 | P a g e It helps to experience the details of work to be executed. It helps to foresee the minor and major components of the project. Estimate will serve as the basis for developing job costing system. It will help to build construction schedule before execution. Job costing system compares actual cost of project at specific time for particular item of estimate. This date tells which item needs more cost control during construction process. It helps to find out duration of work of various activities for construction schedule. Duration of work = magnitude of work / standard output The essence of an estimate consists of forecasting future events in construction process. Then placing currency value on those events. Many additional factors can also affect the future events of construction.For example 1. labor production 2. material availability 3. financial markets 4. weather conditions 5. construct ability issues 6. equipment availability 7. contract types 8. ethics 9. quality issues 10. project control system 11. management ability Qualities of a good estimator Qualities of a good estimator Estimator must have the following qualities: 1. 2. 3. 4. 5. 6. 7. 8. Estimator has ability to read and interpret drawings and specifications. Estimator should have good communication skills. He should have knowledge of basic mathematics. He should have patience. Estimator should have good understandings of fields operations and procedure. He should have ability to visualize three dimensional projects by looking at the drawing. He should have ability to interpret the risks and then neutralize as much as possible. He should have good organizational ability. So that he can communicate his estimate in logical and clear presentation to the client. 9. He should have ability to prepare construction schedule. 10. He should have ability to anticipate all construction steps in building projects. SAQIB IMRAN 0341-7549889 10 11 | P a g e 11. He should have good understanding of labor productivity and equipment performance. 12. He should have ability to use the construction company’s job costing system. 13. He should have ability to think alternate methods of construction. 14. Estimator should have ability to develop strategy for being successful in bidding and negotiation phase of the project. 15. Estimator should have ability to meet deadlines and still remains calm. 16. He should have a solid load of ethics. 17. Estimator should have understanding of contractual relationship. Types and Methods of Rough cost estimate Types of Rough cost estimate Rough cost estimates are of the following types. 1. 2. 3. 4. Preliminary/approximate/rough cost estimate plinth area estimate cube rate estimate approximate quantity method estimate Preliminary/approximate/rough cost estimate Estimate of cost before the construction, from the line planes of architectural drawings when detail and structural drawings are not prepared. Objective of rough cost estimate These estimates are used for obtaining administrative approval from the concerning authority. Method Average unit cost is worked out for projects of similar nature like the project under consideration. In this method average unit cost is multiplied by total quantity of present work in the same unit. Average unit cost like: 1. 2. 3. 4. building cost per person hospital cost per bed student hostel cost per student hostels cost per person SAQIB IMRAN 0341-7549889 11 12 | P a g e Plinth area method Covered area by building is worked out and unit obtained is square feet. For cost per square feet of the covered area, plinth area method is usually used. This method is practical and usual method of obtaining rough cost estimate. Cube rate estimate In cube rate estimate, third dimension height is also considered. Height is multiplied with the covered area. Cube rate is established in this method. The covered area is first calculated and then multiplied with the ceiling height. For each floor level, different cube rate estimate is obtained. Approximate quantity method estimate In this method, a linear length is used for estimation. Therefore, the total length of the object is calculated in running foot. This length is then multiplied with the running cost per running foot of the object to get the cost of the wall. In this method, the structure is divided into sub-structure and super structure. This method is used in roads, railways, bridges, streets etc. By using this method, cost may be found in following ways. 1. For roads and railways, cost/km or cost/miles 2. for streets, cost per 100 feet or cost per 30 meters 3. for bridges, cost per foot or cost per meter of the clear span. Clear span is the clear distance between the supports of the bridges. Types of Detailed cost estimate for construction Types of Detailed cost estimate Types of detailed cost estimate are following: 1. 2. 3. 4. 5. Detailed/item rate estimate. Revised estimate. Supplementary estimate. Supplementary revised estimate. Annual repair and maintenance estimate. SAQIB IMRAN 0341-7549889 12 13 | P a g e Detailed cost estimates Detailed cost estimates are prepared carefully. These calculate in detail the cost of various items work that constitutes the whole project. Detailed estimates are done when the detailed working drawings are prepared along with specifications. If there is any mistake in rough cost estimate, then it will eliminate in detailed cost estimates. These are then submit to the competent authority for obtaining technical sanction. The whole project is divided into different items of work or activities. The quantity of each item will be calculated from drawing as accurately as possible. This procedure is known as taking out quantities or quantities take off. Hand mixing of Cement Concrete Following points must be kept in mind for hand mixing of cement concrete. Hand mixing of cement concrete should be done in masonry platform or iron sheet. For example if we are making concrete of ratio 1:2:4 proportion by hand, first two boxes of sand and one bag of cement should be mixed dry. Mixing of sand and cement should be dry thoroughly. Then this dry mix should be placed over a stack of 4 boxes of stone aggregate. Then this whole mixed dry should be turn at least three times to have uniform mix. Water can be added then gradually with a water-can to the required quantity 25 to 30 litres (5 to 6 gallons) per bag of cement. This water quantity will give the mix required work-ability and water cement ratio. Machine mixing and slump of cement concrete Machine mixing of cement concrete Following points must be kept in mind for machine mixing of cement concrete. Stone ballast, sand and cement to be pour into the cement concrete mixer. For example, for concrete of ratio 1:2:4 first four boxes of stone ballast, then two boxes of sand and then one bag of cement should be put into the cement concrete mixer. The machine then revolve to mix dry materials. Then water should be added to the required quantity, 25 to 30 litres (5 to 6) gallons per bag of cement to have the required water cement ratio. The mixing should be proper to have a plastic mix of uniform color. It requires 1.5 to 2 minutes rotation for proper mixing. Mixed concrete shall be unloaded on a masonry platform or on a iron sheet. Output of concrete mixer is 15 to 20 mix per hour. Slump of cement concrete SAQIB IMRAN 0341-7549889 13 14 | P a g e Slump test is carried out to control the addition of water into the cement concrete. It is carried out to maintain the required consistency. A slump of 7.5 cm to 10 cm (3 inch to 4 inch) is required for building work. For road work it may be 3 to 4 cm (1.5 inch to 2 inch). How to calculate quantity of mortar and its materials Below is the step by step process of calculating quantity of mortar required for cementing. Area of the surface multiply with the thickness gives the quantity of mortar for uniform thickness. This quantity is increased by 30% for filling the joints and to make up uniform surface of wall. It will give wet mixed mortar. This mortar quantity is further increased by 25% to get the dry volume of the ingredients. Quantity of each material of the mortar may be found by dividing the dry volume of mortar by the sum of numerals of the proportions and multiplying the answer with the individual numeral. For example Materials for 12 mm or half inch thick plastering in wall for 100 square meter First of all, we have to multiply 100 square meter surface with 12 mm. 100 square meter x 0.012 m = 1.2 cubic meter. (12 mm can also be written as 0.012) 1.2 cubic meter is wet mixed mortar for uniform thickness. Add 30% in this value to fill up joints, uneven surfaces, etc., the quantity of mortar comes out 1.2 + 0.36 = 1.56 cubic meter. Increasing by 25% the total dry volume will be 1.2+0.36+0.39 = 1.95 cubic meter or 2 cubic meter. For cement sand mortar, cement = dry volume / ( sum of ratios) x numeral of cement. For 1:4 cement sand mortar, cement will be 2/5 x 1 = 0.4 cubic meter. For 1:4 cement sand mortar, sand will be 2/5 x 4 = 1.6 cubic meter. In this way you can calculate the dry volume of any ratio of mortar ingredients. Weight of steel bars per meter – Weight of steel bars formula Here is a list of mild steel bars weight. Diameter of bars in millimeter 6 mm Weight of bars in kilogram 0.22 kg/meter SAQIB IMRAN 0341-7549889 14 15 | P a g e 10 mm 0.62 kg/meter 12 mm 0.89 kg/meter 16 mm 1.58 kg/meter 20 mm 2.469 kg/meter 25 mm 3.858 kg/meter Weight of steel bars formula To calculate weight of steel bars, there is a formula used to calculate weight. W=(D^2 x L)/162 In the above formula: D is in millimeter. L is the total length of steel bars of which weight is to be calculated. For example: if we have to calculate the weight of 10 mm steel bars, then we will proceed as follow: W=10^2/ 162 W=0.617 kg/meter In this way we will get steel bars weight per meter. After that multiply unit weight with the total length of steel bars of which weight is to be calculated. Weight of steel bars per foot in kg Diameter of bars Weight of bars #2 bars (diameter 2/8 inch) 0.075 kg/ft #3 bars (diameter 3/8 inch) 0.170 kg/ft #4 bars (diameter ½ inch) 0.30 kg/ft SAQIB IMRAN 0341-7549889 15 16 | P a g e #5 bars (diameter 5/8 inch) 0.473 kg/ft #6 bars (diameter 6/8 inch) 0.68 kg/ft #8 bars (diameter 1 inch) 1.21 kg/ft How to Calculate The Quantity of Cement And Sand in Mortar Mortar is a mixture of cement, sand, and water. More specifically it is called cement mortar. Cement mortar is used in almost all types of masonry work in civil construction. Such as brickwork, plasterwork, tiles work etc. Although there is dry ready mix mortar available in the market, we often prepare mortar manually in our construction projects. The main ingredients of mortar are cement and sand. In a building project, when we want to start any types of masonry work, we need to stack cement and sand in the project. For stacking cement and sand in the project, we often need to calculate the required quantity of cement and sand for the masonry work. So, let’s see how we can calculate the quantity of cement and sand in the mortar. The quantity of sand and cement in mortar can be calculated in two ways. One is by weight and another is by volume. The easy way to calculate the quantity of cement and sand in mortar is by volume and we often use this method. So, I’ll explain how to calculate cement and sand quantity in the mortar by volume. SAQIB IMRAN 0341-7549889 16 17 | P a g e First of all, you need to know the required quantity of mortar for your masonry work. Then you need to know the proportion of the cement and sand in the mortar. Let’s assume out required mortar quantity is 100 cubic feet and the ratio of cement and sand in the mortar is 1:4. When we say the cement-sand ratio is 1:4, we mean that the mortar contains one part of cement and four parts of sand. But when we get or buy cement and sand, we get those in dry condition. After adding water in the cement-sand mix, the volume of sand is reduced. So, when we calculate the quantity of cement and sand in the mortar, we need to consider the reduced volume of the sand. Considering all these things lets calculate the quantity of cement and sandin the mortar. Get The Required Quantity of Mortar Getting the quantity of mortar for plaster work is easy. You just need to get the plastering area and the thickness of plaster. Then multiply the area with thickness. The result is the quantity of mortar for the plasterwork. Get calculating mortar quantity for masonry wall is a little bit tricky. However, for our calculating purpose let’s assume we need 100 cubic feet mortar. Get The Dry Volume of Mortar As we get the sand and cement in the dry condition we need to get the mortar quantity in the dry state. But when we calculate mortar for any masonry work, we SAQIB IMRAN 0341-7549889 17 18 | P a g e get the wet quantity of mortar. So, we need to convert the wet quantity into dry quantity. To get the dry quantity of mortar, we multiply the wet quantity of mortar with 1.27. That means, The dry quantity of mortar = wet quantity of mortar x 1.27 So, the dry quantity of 100 cubic feet of wet mortar is, = 100 x 1.27 = 127 cubic feet. Get The Cement And Sand Quantity in The Mortar Now it’s time to calculate the quantity of cement and sand in the mortar. For this, we need to know the proportion of cement and sand in the mortar. Different proportion of cement and sand is used in mortar for different types of masonry work. For our calculating purpose, let’s assume we’ll use 1:4. That means, we’ll mix one part of cement with four parts of sand to prepare our mortar. The total part of ingredients is, = 1+4 =5 Calculating The Quantity of Cement So, the quantity of cement is, = 127 ÷ 5 × 1 = 25.40 cubic feet But cement is sold in bags. So, we need to convert the volume of cement into bags. The volume of a 50-kilo bag of cement is 1.25 cubic feet. So, the bag of cement is, =25.40 ÷ 1.25 SAQIB IMRAN 0341-7549889 18 19 | P a g e =20.32 bags Say, 21 bags. Calculating The Sand Quantity The quantity of sand is, =127 ÷ 5 × 4 =101.60 cubic feet. Say, 102 cubic feet Summary Wet mortar volume = 100 Cubic feet Cement-Sand ratio = 1:4 The Quantity of cement = 21 bags The quantity of Sand = 102 cubic feet. How to Calculate Concrete Quantity for Neck Column Either you are going to use ready-mix concrete or on-site machine mix concrete, you need to calculate the concrete quantity of neck columns for ordering readymix concrete or purchasing concrete ingredients. It is our common practice. We often calculate concrete quantity before going to cast any concreting members. There are many things which depend on the concrete volume. Such as required manpower, the tentative cost for the concreting work, etc. SAQIB IMRAN 0341-7549889 19 20 | P a g e The main reason, we calculate concrete quantity for, is to know the volume of concrete or concrete ingredients. In this post, I’ll discuss the manual calculating process for the concrete quantity of neck columns of a building project. What is Neck Column? Neck column is the most bottom part of a column. Saying more specifically, neck column is the part of a column which is buried below ground. The portion between footing and grade beam is normally called neck column. Neck column is also called short column. So, after casting footings of a building project, the next step is to cast neck columns. When we plan to cast neck columns, we need to calculate the concrete quantity for that. How to Calculate Concrete Quantity for Neck Column Calculating concrete quantity for neck column of a building construction project is actually easy. You can do this within a short period of time. Just follow the steps below – Step 1: Get The Total Number of Columns in The Project A building can have many columns of different sizes. There must be some columns with the same size. The first step is to summarize the number of different sizes column. For this, you’ll need column layout and column schedule drawing sheet. You’ll get those drawing sheets in the structural drawing book. Sometimes you’ll find both column layout and column schedule in a single drawing sheet. Sometimes you’ll get two separate sheets. SAQIB IMRAN 0341-7549889 20 21 | P a g e Column layout drawing is that where the column placements for the building are shown. And the column schedule is where size, symbol, and reinforcement details of columns are shown. Columns are normally specified as C1, C2, C3, etc. For estimating neck column concrete you need to find out the total number of different types of columns from the column layout drawing sheet. Summarize the all different types of columns which will look like, for example, below: C1 – 5 numbers C2 – 10 numbers C3 – 7 numbers, etc. Step 2: Get The Size of Neck Column You’ll get the column size and shape form the column schedule drawing sheet. The commonly used shape of columns is round and rectangular/square. Here I would like to explain a most important thing… From my personal experience, I found that the size of neck columns are sometimes not specified in the column schedule drawing separately. Only the size of ground floor columns is shown. But the size of neck column should be bigger than the size of ground floor column. Because the concrete clear cover should be more for neck column as it is built under the ground. In that case, you’ll find the concrete cover for neck column in the general notes sheet of the structural drawing. SAQIB IMRAN 0341-7549889 21 22 | P a g e For example, the concrete clear cover for neck column is specified in the general notes sheet as 2½″and the size of C1 column in ground floor level is shown in the column schedule as 30″x 12″. In this case, the size of neck column (C1) will be 32″ x 14″. Most of the time a separate schedule for neck column is shown in the column schedule drawing. In that case, you don’t have to think about anything. You can proceed to calculate the column area. Suppose, you get the size of the column from the column schedule as below – C1 – 32″x 14″ C2 – 42″x 14″ C3 – 15″x 14″ From these sizes, you can just calculate the column area. But to get the quantity of neck columns’ concrete, you need the third dimension too. That is the height of neck columns. Step 3: Getting Height of Neck columns Getting the height of neck column is a little bit tricky. You need to get the gap between the top of footing and bottom of the grade beam. There may all the footings top isn’t on the same level. And grade beam may not be at the same level too. Then how do you get the height of neck columns? If you already cast footings, you can take measurement practically from the field. That is the most accurate way. I often do this in my project. SAQIB IMRAN 0341-7549889 22 23 | P a g e But sometimes you need to calculate neck column concrete before casting footing. In that case, you need to depend on the drawings. Most of the time you’ll get the data from footing section and grade beam layout drawing. From the footing section drawing sheet, you’ll get the depth of the ground the footing placed on. It is normally shown from road level (土0). For example, I assume that this level is shown in the footing section as -5′. That means the bottom of the footing is place 5′ below the ground. We also need the top level of grade beam which you’ll get from either footing section or grade beam layout drawing. For example, it is specified in the drawing as +3′. Now let’s calculate the height of the neck column. The height of neck column is, = Bottom level of footing + top level of grade beam – the thickness of footing – the thickness of grade beam = 5′ + 3′ – 1′ – 1′ (the thickness of footing and grade beam 1’ – assumed) = 6′ So, The height of neck column is 6′. Now we can calculate the concrete quantity for neck columns. Step 4: Calculating Concrete Quantity for Neck Columns We know, the formula for getting volume is area x height. SAQIB IMRAN 0341-7549889 23 24 | P a g e For square and rectangular size, the area is length x width. But if the column is round shape then the formula for getting the area is πr² (π = 3.14 and r = radius of the column). So, let’s calculate the concrete volume for neck columns which we found in step 1. C1 – 5 x 32″ x 14″ = 5 x 2.67 x 1.17 = 15.62 ft3 (12″ = 1 feet, ft3= cubic feet) C2 – 10 x 42″ x 14″ = 10 x 3.5 x 1.17 = 40.95 ft3 C3 – 7 x 52″ x 14″ = 7 x 4.33 x 1.17 = 35.46 ft3 Total concrete quantity is = 15.62 + 40.95 + 35.46 =92.03 ft3 This is the exactly required concrete quantity for our neck columns. If you plan to cast the neck columns with ready-mix concrete then you can order for this concrete volume. But if you want to use on-site machine mix concrete then you need to calculate the concrete ingredients. I’ve talked about this before in “how to calculate concrete ingredients”. Conclusion Calculating concrete volume for neck columns is actually easy. You just need to get the total numbers of different sizes columns and the size and height of the columns from drawing. And then multiply and sum them up for getting the total concrete volume. SAQIB IMRAN 0341-7549889 24 25 | P a g e How to Easily Estimate Shuttering Materials for Footing Before estimating shuttering materials for footing you need to check the availability of shuttering materials in your project. If you built any other building before you may have some shuttering materials there which you can use in your current project. The purpose of this is to reduce costs as this is the major concern in building construction. As footing is built on the farm base of the ground, so you don’t need to make special formworks for this purpose like column, beam, and slab. Whichever shutter materials are available to you can be used for making formwork of footing. There are various types of formwork materials can be used for footings. You can use plywood, wooden plank or even steel shutter. In my case, if I have any steel shutter in my previous project, I try to use them first. There must be also some shutter material renting company in your area. You can hire shutter from them. The purpose is to reduce cost as the shutter materials for footing is one-time use. Those shutters need to be reassembled for using later. So, it is better to focus on reducing cost in this respect. Whichever shuttering material you have currently try to use those first then calculate rest of the required quantity of materials. As footing shutters are used one time only, it is better not to make new steel shutters for the footing as it is costly. Whichever materials are cheap and available in your area, use those for making formwork of the footing. Mostly used shutter materials for footing is wooden planks, plywood or wooden board as those are cheap and widely available. SAQIB IMRAN 0341-7549889 25 26 | P a g e Estimating shuttering materials for footing is easy. Even a non-technical guy can estimate these. We estimate the shuttering materials for the purpose of purchasing it. Wood and plywood have many uses in a building construction project. So if you purchase some more materials that wouldn’t be a big deal. The purpose of this post is to make the estimating process of shutter materials for footing easy. So that anyone can estimate the materials. So I’m not going to deep technical details as most of them can be ignored. How to Easily Estimate Shuttering Materials for Footing A building has many footings. Not all the footings are different. There must be same types of footings. First of all, summarise the same type of footings. Summarizing footings Footings are normally marked as F1, F2, F3… etc. Suppose, you have 10 numbers of F1 type footing, 6 numbers of F2 type footing, and 8 numbers of F3 type footing, etc. Summarise them all. For summarising similar types of footings you’ll need the footing layout drawing sheet. You’ll find the footing layout drawing in the structural drawing book. There is a problem when summarizing footings. That is you’ll forget which footing you counted from the drawing and which isn’t. To overcome this problem take a pencil and start marking the footing one after another once counted. SAQIB IMRAN 0341-7549889 26 27 | P a g e After counting all types of footings check the footing layout drawing to find out if there is any unmarked footing. If you found any count that too. After finishing this step, you’ll have the numbers of all types of footing. Now count the total number of footings in the footing layout drawing by marking one by one with the pencil. Cross check the total number of footing you found are correct with the counted number. This is not a thumb rule. I just apply this when counting the numbers of footings in a building. If you know any better way you can apply that. The purpose is just to get the exact numbers of different types of footing. Deciding How Many Formworks You’ll Need You don’t need to make formwork for all footings. For example, you have 10 numbers of F1 type footings. All these footing sizes are same. If you just make one formwork for this type, you can reuse that for all 10 footings. This is done for cost saving. You can buy shuttering materials for all 10footings. But that isn’t cost effective. If you are in the tight project schedule and need to finish the project on a short period of time you may need to make formwork for all footings. There are also many things involve deciding how many formworks you need to make for one type of footing. Such as manpower – if you have enough workers, you need to have enough formwork. So that they all can work together. Considering all these things you need to make a decision for how many formworks you’ll make for the footings. If you want to save costs you may make one formwork for three footings and plan for making sufficient formwork for different types of footing. So that, all the workers can work at a time and no workers need to be idle. After casting one set SAQIB IMRAN 0341-7549889 27 28 | P a g e of footings, you can remove the formworks and reuse them in the next set of footings. Estimating Shuttering Materials for Footings It is better to use wooden shutter materials for footing. I won’t recommend making new steel shutter for footings. Because it’s costly. However, you don’t need to estimate exact quantity of wood or plywood for the footings of your building project. If you buy some access wooden plank or some less, that would not make a big difference. You can use the access wooden shutter materials later in some other works. Such as lintel, staircase, etc. If you buy some less quantity of wooden plank, that won’t hamper your project progress. Because if you don’t make a formwork that wouldn’t hamper your project’s progress. Below I’ll show you a simple process to estimate wooden shutter materials for the footing of a building project. Even a non-technical guy can estimate the shuttering materials for footings easily. Follow the steps below – Step 1: Calculate the Periphery Length of Footing Suppose, the size of the F1 footing is, 4′ x 6′ x 1′. So, the periphery length of this footing is, = (4′+6′) x 2 = 20′ Step 2: Calculating The Periphery Area of The Footing SAQIB IMRAN 0341-7549889 28 29 | P a g e The periphery area of the F1 footing is, =20′ x 1′ (the height of the footing is 1′) = 20 square feet (sft) Step 3: Calculating Shuttering Materials What materials do you need to make formwork for footing? You’ll need – Wooden plank or plywood (which is available in your area): The periphery area of the F1 footing is the exactly required area of wooden plank or plywood which is 20 square feet. You need to add 5% extra when ordering wooden plank or plywood. So, required wooden plank or plywood for our footing is, 21 sft. Wooden batten: We normally use 3″x 2″ wooden batten for the formwork of footings. The easiest way to estimate wooden batten is to use a thumb rule which is 2 rft (running feet) per shuttering area. So, required wooden batten for our example footing is, = 2 x 21 = 42 rft (running feet) Nail: the easiest way to estimate nail for formwork is to use a thumb rule which is 0.02 kg for one square foot of shuttering area. So, the required nail for our example footing is, =0.02 x 21 =0.42 kg (kilogram). We have got the required shuttering materials for one formwork of F1 type footing. Based on how many formworks you need for F1 type footing, multiply the shuttering materials we’ve got above with that number. For example, you’ve 10 numbers of F1 type footing and you’ve decided to make 3 numbers of formwork for this type footing. So, required shuttering materials for 3 numbers of formwork for F1 type footings are, Wooden plank or plywood = 3 x 21 = 63 sft SAQIB IMRAN 0341-7549889 29 30 | P a g e Wooden batten (3″x2″) = 3 x 42 = 126 rft Nail = 0.42 x 3 = 1.26 kg. Similarly calculate the shuttering materials for all different types of footing for your building project and summarize them all. conclusion Estimating shuttering materials for footings is actually easy. You just need to decide how many formworks you’ll make for different types of footing. And then calculate wooden plank or plywood, wooden batten, and nail for all the formwork you required. How to Calculate The Concrete Volume for Footings of a Building When you plan to cast footings of a building, you need to calculate concrete volume. Either you use ready mix concrete or plan to cast the footings manually you need to know the exact concrete volume. So that you won’t have excess materials after complete footing casting or you won’t run out of concrete ingredients before completing footing casting. If you plan to use on-site machine-mix-concrete than you have some flexibility. Because if you order for excess concrete ingredients you can use those in some other concreting works. Yet, you need to calculate required concrete volume. So that you won’t run short of concrete ingredients before casting the footing. If you plan to use ready mix concrete to cast the footings, you need to know the exact required concrete volume for ordering concrete. Over-ordering ready-mix-concrete will cost you more. Because ready-mix supplier won’t take ordered concrete back. You will need to pay for excess concrete. SAQIB IMRAN 0341-7549889 30 31 | P a g e As cost is a major issue in construction, you need to control cost by not over ordering ready-mix concrete or over mixing concrete. So, calculate the exactly required concrete volume for the footings before going to cast. In this post, I’ll show you how to calculate the concrete volume for footings of a building easily. How to Calculate Concrete Volume for Footings of a Building Construction Project Calculating concrete volume for footings is easy. You just need to get the volume of different sizes of footings by applying some geometric formula. Let’s see how we can do that. Summarising Similar Types of Footings A building has different types and sizes of footings. They are marked as F1, F2, F3…etc. The first thing you need to do is to summarize them all. For example, The building has 5 numbers of F1 footing, 6 numbers of F2footing, 4 numbers of F3 footing etc. Counting numbers of the same type of footings from the drawing is a little bit tidy. Because you’ll forget which footing you have counted and which you didn’t. The best way to do this is to mark the footing after counting. Take a pencil and mark one after one when counted. SAQIB IMRAN 0341-7549889 31 32 | P a g e After counting all the footings in this way, check the footing layout drawing if any footing is not marked. Unmarked footing means you didn’t count that footing. If you found any footing unmarked, count that too. After summarizing all types of footings, now calculate the concrete volume for each type. Calculating Concrete Volume For calculating concrete volume, you just need to get the volume of some 3D shapes. The shapes can be square, rectangle and trapezoidal. For example, the F1 footing is a square size footing and the dimension is 4′ x 4′ x 1′. So, the concrete volume for this footing is 16 cubic feet. As we have 5 numbers of footings of this type, so the total concrete volume for F1 type is, = 5 x 16 = 80 cubic feet. Again, the F2 footing is a rectangular shape footing and the dimension is 4′ x 6′ x 1′. So, the concrete volume for one footing of this type is 24 cubic feet. As we have 6 numbers of F2 type footing, so the total volume for this type of footing is SAQIB IMRAN 0341-7549889 32 33 | P a g e = 6 x 24 = 144 cubic feet. Again, for example, F3 type footing is a trapezoidal shape and the calculated concrete volume for one footing of this type is 30 cubic feet (assumed). As we have 4 numbers of F3 type footing. So, the total concrete volume for F3 type footing is, = 4 x 30 = 120 cubic feet. Concrete Volume of Footings of a Building Construction Project You may have other types of footings in your building construction project. Calculate concrete volume for all the different types of footings. For keeping this post easy to read and easily understandable, I’ve just shown three types of footing. So, the total concrete volume in footings for our example building project is, = F1 + F2 + F3 = 80+144+120 = 344 cubic feet. This is the exactly required concrete volume for footings of the building project. SAQIB IMRAN 0341-7549889 33 34 | P a g e One Dispute Regarding Concrete Volume There is a dispute regarding concrete volume. That is, do we need to deduct reinforcement volume from concrete volume? I didn’t find any written instruction anywhere about this. Some say we should deduct reinforcement volume and some say we shouldn’t. In my experience, I found that if we deduct reinforcement volume from the total concrete volume, we run short of concrete during casting. So, my recommendation is not to deduct concrete volume from the total volume to find the exact volume. So, how much concrete volume we found in the above calculation for the footings of our example building is the concrete volume we exactly require. Conclusion To calculate concrete volumes for footings you just need to get the volume of some 3D shapes. It is not hard if you know some geometrical formulas. After getting volume for all the different shapes, just grand total them. How to Calculate Quantity of Steel in Footing We often need to calculate steel quantity of different RCC members in a construction project before ordering for purchase. We often do this manually in the project. We actually need to calculate steels for different RCC members when we need that. Because over-purchasing steels (MS Bar) can block a huge amount of money as it is highly priced material. SAQIB IMRAN 0341-7549889 34 35 | P a g e You also can’t order less quantity than the required quantity. Because it will hamper your project’s workflow. So, at different stages of construction of a building project, we need to calculate the steel for different RCC members to know the required quantity. In this post, we will see how to calculate the steel quantity in footings. What is a footing? I think you all know about this. A footing is the most bottom part of a building. And it is a part of the substructure. There are many types of footing used for a building. It depends on the structural design of the building. In this post, I’ll discuss how to estimate reinforcement or steel quantity of a footing How to Calculate Steel Quantity of a Footing Calculating steel quantity of footing is easy. You just need to find out the length of steel bars and then convert the total length of bars into kilogram as steel is sold in Kilograms or Tons (1 Ton=1000 kilogram). The process to calculate steel quantity is same for different types of footings. Once you’ve learned to estimate steel quantity for one type of footing, you’ll be able to estimate steel quantity for any type of footings. So, I’ll show you how to calculate steel quantity for an Isolated footing. What is an Isolated Footing? An isolated footing is normally used to support a single column. It can be a square or rectangular shape. SAQIB IMRAN 0341-7549889 35 36 | P a g e If you know how to calculate the quantity of steel for an isolated footing, you’ll be able to calculate steels for other types of footings. So, let’s see how to calculate steel quantity for an isolated footing. How to Calculate Steel for an Isolated Footings You’ll need structural drawing sheets of footings for calculating steel. Things you’ll require for estimating steel quantity of footings – Size of footings Reinforcement details of footings In structural drawings, you will find all the details required to calculate steel and it is somehow shown in the drawing as shown in the image below. From the above image, the size of the footing is 4′ x 6′ x 1′ And, The reinforcement details are, 16 mm∅ [email protected]″c/c along the long side, and 20 mm∅ [email protected]″ c/c along the short side. SAQIB IMRAN 0341-7549889 36 37 | P a g e That means you’ll need to place 16mm dia bar at 4″ center-to-center (c/c) distance along the long side and 20mm dia bar at 4″ center-to-center (c/c) distance along the short side of the footing. So, let’s calculate the steel quantity for the footing. To calculate the steel quantity, we first need to calculate the required number of bars for both directions. Then we need to find the length of one bar. If you multiply the number of required bars with the length of one bar then you will find the total length of bars. Once you found the total length of bars, you need to convert that length into kilograms or Tons. So, let’s see how we can calculate the steel quantity for our example footing. A formula for Calculating The Number of Bars To find out the required number of bars for a footing, use the following formula, Number of bars = {(length or width of footing – concrete cover for both sides) ÷ spacing} +1 For our example footing, Number of bars along the short side of the footing, = {(6′ – 3″ x 2) ÷ 4″} + 1 [Concrete clear cover for footing is 3″] = {(6′ – 6″) ÷ 4″} + 1 = (5½′ ÷ 4″) +1 = 17.67 SAQIB IMRAN 0341-7549889 37 38 | P a g e Say, 18 Nos. Number of bars along the long side of the footing, = {(4′- 3″ x 2) ÷ 4″}+1 = {3½′ ÷4″} + 1 = 11.61 Say, 12 Nos. A formula for calculating the length of a steel bar To find out the length of a steel bar use the following formula. Length of a bar = length or width of footing – concrete cover for both sides + 2 x length of a bend For our example footing, Length of a steel bar along the width of the footing, = 4′ – 2 x 3″ + 2 x 6″ = 4½ feet. Length of a steel bar along the long side of the footing is, = 6′ – 2 x 3″ + 2 x 6″ = 6½ feet. SAQIB IMRAN 0341-7549889 38 39 | P a g e Finding total length of bars in the footing The total length of bars along the short side of the footing is, = number of bars x length of a bar = 18 x 4½′ = 81 feet (20mmØ bar). The total length of bars along the long side of the footing is, = number of bars x length of a bar = 12 x 6½′ = 78 feet (16mmØ bar). If the same size of bars is used in both directions then you can sum up both quantity of the bars. But, in our example footing, we used different size of bars. So, we will calculate the steel quantity for different diameter bars separately. For purchasing the steel, we need to convert the required length of steel into kilogram. From the above calculation, we found – Required 16mmØ bar for our example footing is, = 81 feet = 38.88 kilograms And, Required 20mmØ bar is, SAQIB IMRAN 0341-7549889 39 40 | P a g e = 78 feet = 58.50 kilograms In our example footing, we use a single reinforcing net. But, in your building project, you may find some footings with the double reinforcing net. In that case, you need to follow the same procedure again to calculate the steel quantity for another reinforcing net too. So far, we calculated the quantity of steel for a footing. Now let’s see how we can calculate footing’s steel quantity for a building project. How to Calculate The Steel Quantity in Footing for a Building Project A building has many footings with different sizes and shapes. You’ll need to calculate the steel quantity for those footings too. For making the steel calculating process easy for footings of a building construction project, first, summarise the similar type of footings Secondly, calculate the steel quantity for each type of footing separately and Finally, multiply the calculated steel quantity by the number of each type of footings. For example, you have 10 numbers of footing for F1 type and 5 numbers of footings for F2 type and so on. For calculating the steel quantity for F1 type footing, you just need to calculate the required steel quantity for one footing of that type and then multiply that quantity by 10. Similarly, for F2 type footing, calculate the steel quantity for one number of footing than multiply that quantity by 5. And so on. SAQIB IMRAN 0341-7549889 40 41 | P a g e After calculating steel quantity for the footings of the building project, add the steel quantity for short columns before purchasing. Because you will need the short columns’ steel for completing the footings’ reinforcement works. Conclusion Calculating steel quantity for footings is easy. You just need to get the total required length of the steel bars of different sizes and then convert that length into Kilograms or Tons before purchasing. What Should Be the Standard Door Frame Width? You should understand the standard door frame width properly as it is related to door shutter width. Let’s understand some terms first related to this issue for better understanding the standard door frame width. Door shutter width: This is somehow the clear opening of a door. That means, it is the inner width of a door frame. Door frame width: Door frame width is the outer width of a door frame. Door rough opening width: Door rough opening is the opening we keep on a wall to fix a door frame. So, the width of opening in a masonry wall to be fixed a door frame is the width of door rough opening. Now let’s take a look at a door frame. SAQIB IMRAN 0341-7549889 41 42 | P a g e Anatomy of a door frame A door frame consists of three parts. Two Jambs and one Head. Jamb: Jamb is a vertical part of a door frame. A door frame has two Jambs. The length of a jamb is normally 84“. And the cross-sectional dimension of a jamb is normally 6” x 2½”. But if you plan to fix tiles in a wall then the cross-sectional dimension of a Jamb should be 6½” x 2½”. For example, bathroom wall and kitchen wall. Head: Head is the horizontal part of a door frame. A door frame has one head. The length of a head should be same as the width of a door frame. And the cross-sectional dimension of a head should be same as the crosssectional dimension of jamb for the particular door frame. As you now know about the door frame particularly, let’s move on to understanding Standard door frame width. SAQIB IMRAN 0341-7549889 42 43 | P a g e What should be the standard door frame width In architectural drawing, we commonly see the door width as below – For Bedrooms – 40” For Kitchen – 36” For Bathrooms – 30”, etc. Let’s take a bathroom door for the sake of our example which is 30” width. So the width of the door frame for the bathroom will be 30”. Let’s see what will be the door shutter opening width for the door. Jamb thickness = 2 x 2½“ = 5” Bit thickness for fixing door shutter in both Jambs = 2 x ½” = 1”. So, the door shutter opening width will be, = 30” – 5” + 1” = 26” SAQIB IMRAN 0341-7549889 43 44 | P a g e The available door shutter size in the market is 24”, 27”, 30”, 33”, 36”, etc. So, if you keep the door shutter opening 26”, you won’t face any problem fixing 27” width door shutter. Because, if the door shutter opening is increased for some reason (straightening, sandpapering, etc) and the door shutter width is reduced for some reason (straightening, etc.), you will be able to fix the door shutter in the door shutter opening. But there is a problem with 40” wide door. The bedroom doors are often shown in the architectural drawing as 40”. Let’s calculate the required door shutter width for the 40” wide door. Required door shutter width for the 40” wide door frame is, = door frame width – 2 x jamb thickness + 2 x bit thickness. = 40” – 2 x 2½“ + 2 x ½“ = 36”. The available door shutter width in the market for the door is 36”. But, if you take some portion from Jambs and some portion from door shutter for straightening and sand papering purpose, you won’t be able to fix the 36” wide door shutter in the opening. So, although the door width is shown in the architectural drawing as 40”, you should use the 39” width door frame for bedrooms. So, the standard door frame width depends on the available door shutter width in the market. SAQIB IMRAN 0341-7549889 44 45 | P a g e When we talk about the standard door frame width, we actually talk about the standard door width. Although some codes are discussed on the standard door size, I’m not talking about those codes. But, we normally use standard door width for various types of rooms in an apartment as following – For, main entrance door – 45” Bedroom Door- 39” Bathroom – 30” Kitchen – 36” Kitchen veranda and servant toilet etc – 25”. Keep in mind that you will also find a readymade door in the market which is combined with the door frame and door shutter. Thus you don’t need to calculate all these things. However, standard door frame width depends on the width of door shutter. So, whatever door size is shown on the drawing doesn’t matter, you should check which door shutter width you will be able to provide. How to Estimate Concrete Volume for Staircase? Estimating concrete volume for staircase is a little bit tidy as it is inclined and has geometrical shapes. But we can do that easily using some formulas. SAQIB IMRAN 0341-7549889 45 46 | P a g e Let’s first know deeply about a staircase. Staircase and Its Parts A staircase is an essential part of a building which is provided to make a path between two floors. A staircase has mainly two parts – Step and Landing. Step: A step is normally a triangular shaped part of a staircase which sits on an inclined slab (Waist slab). A step also has two parts – Riser and Tread. Riser: Riser is the vertical portion of steps. Normally, the height of a riser is 6 inches. Tread: It is the horizontal part of a step. The width of a tread is normally kept 10 inches. Landing: It is a horizontal slab which is provided in between the flights of a staircase. It is mainly provided for changing moving direction of a stair. It also gives users comport to climb. Flight: A staircase normally has two flights. One is below the landing and another is above the landing. The flight below the landing is called first flight and the flight above the landing is called 2nd flight. This is somehow an anatomy of a staircase. SAQIB IMRAN 0341-7549889 46 47 | P a g e To estimate concrete volume for a staircase, you need to calculate all these parts of a staircase. Let’s see how we can do that. How to Estimate Concrete Volume for a Staircase? Estimating concrete volume for a staircase, you need to calculate the concrete volume for, Steps and waist slab of 1st flight Steps and waist slab of 2nd flight, and Landing. See the image below. In the image, we have a plan of a staircase. SAQIB IMRAN 0341-7549889 47 48 | P a g e Now Let’s calculate the concrete volume for the staircase. Concrete volume for 1st flight of the staircase From the above two images – Riser = 6 inches Tread = 10 inches Length of a step = 4 feet Number of steps = 9 Thickness of waist slab = 6” Concrete volume for the waist slab SAQIB IMRAN 0341-7549889 48 49 | P a g e To know the concrete volume for the waist slab, we need to calculate the inclined length of the waist slab. Inclined length of waist slab isn’t normally shown in the drawing. But we can calculate that from the architectural plan. let’s calculate. Horizontal length of a waist slab is, =number of steps x tread = 9 x 10” = 7′-6”. The height of the landing top from floor is, = number of riser x height of riser = 10 x 6″ [number of riser = number of steps = 1] = 5 feet. So the inclined length of the waist slab is, =√{(horizontal length)2 + (Height)2} SAQIB IMRAN 0341-7549889 49 50 | P a g e = (7’-6”)2 + (5’)2 = 9’ (round up) So, the concrete volume for the waist slab is, = inclined length of waist slab x width of waist slab (width of a step) x thickness of waist slab = 9’ x 4’ x 6” = 18 cubic feet Concrete volume for steps As steps are triangular shape so the volume of a step is, = ½ x tread x riser x length of step = ½ x 10” x 6” x 4 = 0.84 cubic feet As we have 9 numbers of steps in a flight, so the concrete volume for the steps of first flight is, = 9 x 0.84 = 7.56 cubic feet SAQIB IMRAN 0341-7549889 50 51 | P a g e So the total concrete volume for the 1st flight of the staircase is, = Waist slab concrete + steps concrete = 18 + 7.56 = 25.56 cubic feet Concrete volume for 2nd flight of the staircase As the 1st flight and 2nd flight are same in our example drawing (above image) so the concrete volume will be same. That is, = 25.56 cubic feet Now, we need to calculate the concrete volume for landing. Concrete volume for the stair landing From our example drawing, Length of landing = 8’-6” Width of landing = 4’-6” Thickness of landing = 6” So, the concrete volume for the landing is, = 8’-6” x 4’-6” x 6” SAQIB IMRAN 0341-7549889 51 52 | P a g e = 19.12 cubic feet So, total concrete volume for the staircase is, = 1st flight concrete + 2nd flight concrete + landing concrete = 25.56 + 25.56 + 19.12 = 70.24 cubic feet Estimating concrete volume for a staircase isn’t so difficult. We just need to apply some geometric formula. Nowadays, getting concrete volume for any shape of a structure is just a matter of few clicks in AutoCAD. But, in a construction project, we don’t always have access to computers. So, often we need to do it manually. How to Calculate Wooden Formwork for Grade Beam? Most of the time we use wooden formwork for constructing grade beam. In this post, we’ll see, how to calculate the wooden formwork for grade beam. First we need to know what is grade Beam? Grade beam is a sub-structure of any structure which is normally built on short column. Grade beam is also called tie beam. SAQIB IMRAN 0341-7549889 52 53 | P a g e You can use different types of shutter materials for the foomwork of grade beam. Such as steel shutter materials and wooden shutter materials. When shutter materials are used to make a concrete form than it is called concrete formwork. How to Calculate Wooden Formwork for Grade Beam? Before calculating the wooden formwork, you need to know how the grade beam will be constructed? Grade beam can be constructed directly on the ground or above from the ground. If the grade beam is constructed directly on the ground then you don’t need to calculate the shutter materials for the bottom of the beam. In that case, a brick flat soling is done on the compacted soil and then the formwork is fixed with the brick flat soling for constructing the grade beam. But, if the grade beam is constructed above the ground then you need to calculate the shutter materials for bottom side of the beam. We will calculate the formwork for both case. So, let’s begin calculating the wooden formwork for a grade beam. The details of the grade beam is given below. Grade beam details: SAQIB IMRAN 0341-7549889 53 54 | P a g e Size – 10″ x 12″ Length – 14′ Required shutter materials for the formwork of the grade beam: 1½” thick wooden plank 2″ x 3″ wooden button So, we need to calculate the above two shutter materials for the formwork of grade beam. Calculating wooden plank: Required 1½” wooden plank for one side of the grade beam – Length of grade beam: 14′ Height of grade beam: 1′ So, Volume of wooden plank for the formwork of one side of the grade beam is, = 14′-0″ x 1′-1″ (1″ extra height for jointing) x 1½” = 1.90 cubic feet. For another side of the grade beam, you’ll require the same quantity of wooden plank. That is, 1.90 cubic feet. Total required volume of 1½” wooden plank is, = 1.90 x 2 SAQIB IMRAN 0341-7549889 54 55 | P a g e = 3.80 cubic feet. If the grade beam is built directly on the ground then you’ll need this quantity of 1½” wooden plank for the formwork of the beam. But, if you want to build the grade beam above the ground then you’ll require more wooden plank for the formwork of the bottom side of grade beam. So, let’s calculate the shutter materials for the formwork of grade beam bottom. Length of grade beam: 14′-0″ Width of grade beam: 10″ So, required wooden plank for the bottom of grade beam is, = 14′-0″ x 10″ x 1½” = 1.46 cubic feet. In this case, total required wooden plank for the formwork of grade beam is, = 3.80 + 1.46 = 5.26 cubic feet. Now let’s calculate 2″ x 3″ wooden button. SAQIB IMRAN 0341-7549889 55 56 | P a g e Calculating 2″ x 3″ wooden button for the formwork of the grade beam Wooden button is placed 2′ center to centre distance. As our grade beam is 14′ long, so the required number of wooden button for one side of the beam is, = 14/2 + 1 = 8 nos The length of a wooden button is 1½’ as our beam is 1′ hight. So, volume of 2″ x 3″ wooden button for one side of the grade beam is, = 8 x 1½’ x 2″ x 3″ = 0.50 cubic feet. For both side of the grade beam, required button is, = 2 x 0.50 = 1.0 cft. If your grade beam will be built above ground, then you’ll also need wooden button for the bottom side of the beam. So, required wooden button for the bottom side of the grade beam is, = 8 x 1½’ x 2″ x 3″ SAQIB IMRAN 0341-7549889 56 57 | P a g e = 0.50 cubic feet. Summary: If the grade beam is built on ground – 1½” wooden plank: 3.80 cubic feet 2″ x 3″ wooden button: 1.0 cubic feet If the grade beam is built above ground (shutter for bottom side of the beam will be added) – 1½” wooden plank: 5.26 cubic feet 2″ x 3″ wooden button: 1.50 cubic feet Conclusion: If you don’t use wooden button for supporting the grade beam, then only the above calculated wooden shutter materials will be required for the formwork of the beam. But, if you want to use wooden button for supporting purpose also then you need to calculate those for the formwork of the grade beam. When you order for wooden shutter materials, always add extra 5% with the calculated quantity. What Should Be Standard Size of Rooms in Residential Building? SAQIB IMRAN 0341-7549889 57 58 | P a g e I’ve been asked this question many times by my relatives as well as by my clients. That is, what should be the standard room size for a residential building? In this post I’ll answer this question from my experience which I gained from last 14 years of time working with several architects and clients. Before knowing standard room size, we need to know what types of room we may have in a residential building. Type of rooms in a residential building Although type of rooms depend on the personal preference, here are some common types of room we normally build in a residential building: Living room Master bed room Child bed room Guest Bed Room Dining room Kitchen Bath room Dressing room Foyer Store Room Pantry Office room, etc. You can also include some other type of rooms in your residential building. For example, you may want to include a “study room” in your residential building. SAQIB IMRAN 0341-7549889 58 59 | P a g e Now we’ll talk about these various type of rooms-How they can be locatedand what are the standard size of those rooms in a residential building? Standard size of rooms in a residential building Once I worked with a client, who built his living room such big that we can make a whole apartment in his living room, if we take standard room size. So, when I’m asked about the standard size of rooms in a residential building by my relatives or clients then I always confused that what I should say. Because, when I tell them standard size of a room, they replied, this is too small or this is big! So, size of a room in a residential building completely depends on your personal preference. However, everything has a standard, if you like it or not. So, let’s talk about the standard size of various type of rooms in a residential building. Living room: We all know about this room. It is used for sitting and gossiping purpose with guest or friends. It is also called drawing room. Location of living room: During locate living room in your apartment, keep the following things in mind – Locate the living room near main door. SAQIB IMRAN 0341-7549889 59 60 | P a g e Locate the living room near the dining room. Sometimes, living room is used as dining room. In that case, living room should be bigger than standard size. Try to locate the living room in the middle of your apartment’s front side. Standard size of living room: the standard size of a living room should be as below – Small: 12′ x 18′ (3600mm x 5400mm) Medium: 16′ x 20′ (4800mm x 6000mm) Large: 22′ x 28′ (6600mm x 8400mm) Master Bed Room: Master bed room is the main bed room of an apartment. Location of master bed room: keep the following things in mind during locating master bed room in your apartment – Master bed room should be well ventilated. So, locate this bed room in such a way that it can get enough ventilation. Try to keep at least one wall of master bed room expose to outer for sufficient ventilation. Locate your master bed in the side of the building where natural view is visible. Locate the master bed in such a way that it provides privacy. Locate the master bed room in such a way that it receives enough sunlight in the morning. SAQIB IMRAN 0341-7549889 60 61 | P a g e Standard size of master bed room: Master bed room should be bigger in size than other bed room. The standard size is, Small: 12′ x 14′ (3600mm x 4200mm) Medium: 14′ x 20′ (4200mm x 6000mm) Large: 16′ x 24′ (4800mm x 7200mm) Child bed room: Child bed room is made for children. This room is like any other bed room. Location of child bed room: During locate the child bed room, consider the things which we considered during locating the master bed room. Most of the time it is not possible to give all the facility of master bed room to child bed room. In that case, you need to deduct some facility. Okay, no problem, children will understand that. Size of child bed room: Child bed room is not as big as master bed room. The size of child bed room is as the size of normal bed room. However, the standard size is, Small: 10′ x 12′ (3000mm x 3600mm) Medium: 12′ x 14′ (3600mm x 4200mm) Large: 14′ x 16′ (4200mm x 4800mm) Guest bed room: SAQIB IMRAN 0341-7549889 61 62 | P a g e Guest bed room is as normal bed room and it is made for guest. It can also be called common bed room. Location of common bed room: To locate the guest bed room, consider the following things – If possible try to locate this bed room in a well lighted and ventilated place. During locating guest bed room, consider the privacy of family members. Because guest bed room will be used by guest. So, it is essential to disconnect this room from rest of the rooms of the apartment. Guest room should be located in the front of the apartment and beside the living room. Standard size of guest bed room: The standard size of guest bed room is, Small: 10′ x 12′ (3000mm x 3600mm) Medium: 12′ x 14′ (3600mm x 4200mm) Large: 14′ x 16′ (4200mm x 4800mm) Dining room: We all know about the dining room. We sit and take our food here. Location of dining room: Consider the following things during locating dining room in your apartment – SAQIB IMRAN 0341-7549889 62 63 | P a g e Dining room should be located near the kitchen room and back side of living room. In the modern apartment, dining and living room are combined together to get a big room for family occasion like birthday party. So, you can do the same too. Standard size of dining room: If you want to separate your dining room from living room then the standard size of dining room is, Small: 10′ x 12′ (3000mm x 3600mm) Medium: 12′ x 14′ (3600mm x 4200mm) Large: 14′ x16′ (4200mm x 4800mm) Kitchen We know this room very well. It is the room to cook food for our family. Location of kitchen room: Considering things during placing kitchen room in a residential building – Kitchen room should be located near the dining room. At least one wall of kitchen room should beexposed to outer for escaping smoke. It should be placed in such a way so that it has enough sunlight and air circulation. Standard size of kitchen room: Although some prefer to make a big kitchen room, the standardsize of it is, Small: 5′ x 10′ (1500mm x 3000mm) SAQIB IMRAN 0341-7549889 63 64 | P a g e Medium: 8′ x 13′ (2500mm x 3900mm) Large: 10′ x 12′ (3000mm x 3600mm) Bathroom: There are two type of bathrooms can have in an apartment of a residential building. One is master bathroom and another is common bathroom. Master bathroom is generally attached with master bedroom. We can also have an attached bathroom with child bedroom. But, the guest room doesn’t need to have attached bathroom. For this purpose, it is better to have a common bath room for guest. Standard size of bathroom: Although the size of master bathroom depends on the personal preference, the standard size of a master bath is, Small: 6′ x 9′ (1800mm x 2700mm) Medium: 7′ x 10′ (2100mm x 3000mm) Large: 8′ x 12′ (2500mm x 3600mm) Standard size of common bathroom, Small: 5′ x 9′ (1500mm x 2700mm) Medium: 6′ x 10′ (1800mm x 3000mm) SAQIB IMRAN 0341-7549889 64 65 | P a g e Large: 7′ x 12′ (2100mm x 3600mm) Dressing room: Dressing room is provided in front of Master bathroom. It doesn’t need to provide dressing room with any other bathroom. But it depends on you. standard size of dressing room: The standard size of dressing room is, Small: 4′ x 4′ (1200mm x 1200mm) Medium: 5′ x 5′ (1500mm x 1500mm) Large: 6′ x 6′ (1800mm x 1800mm) Foyer: Foyer is a lobby or corridor used in an apartment of a residential building to separate the entrance from living room. But some prefer to omit the foyer and use the living room as an entrance of the apartment. The standard size of foyer: Small: 5′ wide (1500mm) Medium: 6′ wide (1800mm) Large: 8′ wide (2500mm) Store room: SAQIB IMRAN 0341-7549889 65 66 | P a g e Store room is used for storing the kitchen goods. It should be placed near the kitchen room. And it should have sufficient rack to store materials. Standard size of Store room: The standard size of a Store room is, Small: 6′ x 6′ (1800mm x 1800mm) Medium: 8′ x 10′ (2500mm x 3000mm) Large: 10′ x 10′ (3000mm x 3000mm) Pantry Although kitchen serves the purpose of pantry, someone prefer to have a pantry adjacent to kitchen. Pantry is a small room where cooked foods are kept. It should have sufficient rack and cupboard. Standard Size of pantry: The standard size of pantry is, Small: 2′ x 2′ (600mm x 600mm) Medium: 3′ x 4′ (900mm x 1200mm) Large: 4′ x 6′ (1200mm x 1800mm) Office Room: You can use the guest room as an office room. Because, guest room isn’t always used. But some prefer to have a separate office room in an apartment. SAQIB IMRAN 0341-7549889 66 67 | P a g e The location of office room should be in front of apartment like guest bed. Standard size of office room: Although the size of office room depends on personal preference, the standard size of the room is, Small: 8′ x 10′ (2500mm x 3000mm) Medium: 10′ x 12′ (3000mm x 3600mm) Large: 12′ x 14′ (3600mm x 4200mm) You don’t have to build the rooms in your apartment as standard sizes. You should define the size of rooms as your personal requirement. So increase or decrease the size of rooms that best suites you. How to Estimate Beam Reinforcement An ordinary person can estimate reinforcement as lumsum. I see many people estimate reinforcement as a percentage of concrete volume. Such as 2% or 1.5% of concrete volume. But as a construction professional you shouldn’t estimate rebar quantity as percent of concrete volume. You should estimate that as shown in the structural drawing. Estimating rebar quantity is easy. All you have to get the cutting length for each type of bar in the beam. Let’s start estimating. We’ll use the following image as a structural drawing of beam. SAQIB IMRAN 0341-7549889 67 68 | P a g e Process of Estimating Beam Reinforcement From the image above we have found – Top longitudinal bar, T – 3D20 Bottom longitudinal bar, B – 3D20 Extra top bar on support1, Et1 – 2D20 Extra top bar on support2, Et2 – 2D20 Extra bottom Bar, Eb – 2D20 Stirrup, S1 – D10 @ 4″ c/c If you don’t know the name of bar on different location in a beam then read the following post. You will also need the following data to estimate the beam reinforcement – Clear cover for reinforcement Lap length Bend length You’ll get this data from the general notes sheet of structural drawing. That’s fine. SAQIB IMRAN 0341-7549889 68 69 | P a g e We have enough data to estimate the beam reinforcement. Let’s estimate. Top Longitudinal Bar (T) Apply the following formula to get the cutting length of top longitudinal bar. Cutting Length of top longitudinal bar is, = Length of beam – 2 x clear cover + 2 x bend length – 2 x bend deduction length + lap length Length of beam: 20″ + (22′-8″) + 20″ + (8′-4″) + 20″ = 36′ (from above image) Clear cover: 1½” Bend length: 12D = 12 x 20 = 240 mm, say 9½” Bend deduction length: Bend deduction length for 90° bend is equal to two times of bar dia = 2 x 20 mm = 40mm = 1½” So, the cutting length of the top longitudinal bar is, = 36′ – 2 x 1½” + 2 x 9½ – 2 x 1½” + 0 = 37′-1″. There are 3 numbers of top longitudinal bar in the above image. So the total length of top longitudinal bar is, = 3 x (37′-1″) = 111′-3″. We know the full length of a reinforcing bar is about 40′. The length of a top longitudinal bar, we are estimating, doesn’t exceed the length of a full bar. So you don’t have to add lap length. SAQIB IMRAN 0341-7549889 69 70 | P a g e Bottom Longitudinal Bar (B) The formula for calculating the cutting length of bottom longitudinal baris same as the formula for top longitudinal bar. So the length is also same as T1 . That is 37′-1″. So the total length of B1 bar is, = number of B1 bar x cutting length of a B1 bar = 3 x (37′-1″) =111′-3″. Extra Top Bar on Support1 (Et1) Calculating cutting length of extra top bar follow the following formula – Cutting length of Et1 = extended length from support + width of support – clear cover + bend length – bend deduction length Extended length from support: 7′-5″ Width of support: 20″ Clear cover: 1½” Bend length: 9½” Bend deduction length: 1½” So the cutting length of Et1 is, = (7′-5″) + 20″ – 1½” + 9½” – 1½” = 9′-7½” SAQIB IMRAN 0341-7549889 70 71 | P a g e There are 2 number of Et1 bar shown in drawing (image above). So the total length of Et1 is, =2 x (9′-7½”) = 19′-3″ Extra Top Bar on Support2 (Et2) Extended length fron support: 7′-5″ Width of support: width of support for Et2 should be the width of support2 + distance between support2 and support3 + width of support3 = 20″ + (8′-4″) + 20″ = 11′-8″ Clear cover: 1½” Bend length: 9½” Bend deduction length: 1½” So, cutting length of Et2 = (7′-5″) + (11′-8″) – 1½” + 9½” – 1½” = 19′-7½” Total length of Et2 = 2 x (19′-7½”) = 39′-3″ Extra bottom bar (Eb) Cutting length of extra bottom bar is, =Distance between support – 2 x distance between extra bottom bar and nearest support = (22′-8″) – 2 x (2′-10″) = 17′ Total length of extra bottom bar is, = 2 x 17′ (there are 2 bar for Eb shown in the image above) SAQIB IMRAN 0341-7549889 71 72 | P a g e = 34′ Stirrup (S1) For estimating stirrup you have to calculate the required number of stirrup for the beam and cutting length of bar for a stirrup. Number of stirrup: Required number of stirrup for 1st span, = (22′-8″)/4″ +1 = 69 + 1 = 70 nos. Required number of stirrup for 2nd span, = (8′-4″)/4″ + 1 = 25 + 1 = 26 nos. Total number of stirrups = 70 + 26 = 96 nos. Formula for calculating cutting length of a stirrup’s bar is, = 2 x (a+b) + 24D (for 135° hook) Where, a = length of stirrup’s long side b = length of stirrup’s short side D = dia of stirrup bar So cutting length of the bar is, = 2 x (21″+9″) + 24 x 10mm = 69½” (240 mm = 9½”) = 5′-9½” SAQIB IMRAN 0341-7549889 72 73 | P a g e Total length of bars for all stirrups, = 96 x (5′-9½”) = 556′ Summary: Total reinforcing bar we have estimated for the beam so far – 20 mm ø bar – T = 111′-3″ B = 111′-3″ Et1 = 19′-3″ Et2 = 19′-7½” Eb = 34′ So total 20 mm ø bar is, = 111′-3″ + 111′-3″ + 19′-3″ + 19′-7½” + 34′ = 296′. 10 mm ø bar, S1 = 556′ But steel reinforcing bars are measured in kg in the market. So you have to convert the bar length to kilogram. Unit weight of 10 mm ø bar is 0.188 kg/ft and 20 mm ø bar is 0.75 kg/ft. Read the following post to know how to calculate unit weight of reinforcing bar. So reinforcement required for our example beam, 20 mm ø bar = 296′ x 0.75 = 222 kg 10 mm ø bar = 556 x 0.188 = 105 kg SAQIB IMRAN 0341-7549889 73 74 | P a g e That’s it. When you want to purchase reinforcing bar for the beam you should add 5% more with your estimated quantity as wastage. 4 Terms to Understand to Truly Estimate Rebar Quantity Estimating Reinforcement is easy. All you have to get the cutting length of bar and convert them to weight. When estimating rebar for a rcc member you have to understand few terms clearly regarding reinforcement. 4 Terms to understand to truly estimate rebar quantity Below are 4 terms you should understand clearly to truly estimate the rebar quantity – 1. True length of bar 2. Cutting length of bar SAQIB IMRAN 0341-7549889 74 75 | P a g e 3. Bending length of bar 4. Bend deduction length 1. True Length of Bar For estimating rebar quantity we just calculate the length of some leaner shapes of bar. For example, take a top longitudinal bar of a beam. The shape of the bar will look like the image below. For estimating purpose we just get the length of the bar and convert it to the weight of bar. Let’s calculate the bar in the image above. The length of that bar is, =A+B+C Suppose, A is = 20′, B is = 1′ and C is = 1′ So the length of the bar is, = 20′ + 1′ + 1′ =22′ This is the true length of bar. 2. Cutting Length of Bar As we know steel is ductile and subjected to elongation. When it bends it is increased in length. SAQIB IMRAN 0341-7549889 75 76 | P a g e So if you we cut the bar as its true length and bend it we won’t get the desired shape after bend. To get the desired shape, the bar should be cut lesser than the true length. The required length to get the desired shape of the bar is calledcutting length of bar. 3. Bending Length of Bar Now the question is how much a reinforcing bar is increased in length when it is bent? It depend on the size of bar and angle of the bend. The increased length for specific diameter of bar for specific angle is called bending length of the bar. 4. Bend Deduction Length It is confusing. Because bend deduction length conflicts with the bending length. Actually both the terms are same. Then why the engineering world using both terms to confuse the fresher? This question is mine. The purpose for writing this post is to eliminate the confusion between these two terms. Don’t be confused. Both terms are same. When we deduct the bending length from the true length of a bar then it is calledbend deduction length. SAQIB IMRAN 0341-7549889 76 77 | P a g e Mostly used bend angle in civil construction world are 45° and 90° bend. For 45° bend, Bend deduction length is equal to dia of bar. and For 90° bend, bend deduction length is equal to two times of bar dia. Bend deduction length is actually used for calculating the cutting length of bar in construction. Let’s calculate the cutting length of the bar shown in the image above. Cutting length = true length of bar – (2 x dia of bar) x number of bend. = 22′ – 2 x ¾” x 2 (20 mm = ¾”) = 21′-9″ For estimating purpose only, you don’t have to deduct the bend deduction length form the true length of bar. It is required when you are cutting bar or making bar bending schedule for placing reinforcement in the rcc member. How to Calculate the Unit Weight of Steel Bars There is a formula to calculate the unit weight of steel bars. I’ll come that point later. SAQIB IMRAN 0341-7549889 77 78 | P a g e Why do we need to know the unit weight of steel bars? When we estimate the steel bars for a Reinforced Concrete member we get the length of that as a result. For example, 1000 feet 20mm ø bar or 500 feet 16mm ø bar, etc (ø – symbol of diameter). But steel bar suppliers measure the steel bars as weight. So we have to order them in weight for purchasing. The weight of steel bars can be expressed in kg or quintal or ton. 1 quintal = 100 kg 1 ton = 1000 kg or 10 quintal Now come to the point. How to Calculate the Weight of Steel Bars We often use a formula for Calculating the weight of Steel Bars. The formula just converts the length of steel bars to weight. We can also use this formula to know the unit weight of steel bars of different diameter. The Formula: D²L/162 SAQIB IMRAN 0341-7549889 78 79 | P a g e Where, D = Diameter of steel bar in millimeter L = Length of steel bars in meter Understanding the Formula We know, the weight of a material is, = Cross sectional area of the material x Length of the material x Density of the material For steel bar this is also same. Weight of steel bars= Cross sectional area of steel bar x Length of steel bar x Density of steel bar. That means, W=AxLxρ Where, A = Area = πD²/4 π (pai) = 3.14 D = Diameter of steel bar in millimeter L = Length of steel bar in meter ρ (Rho) = Density of steel bar = 7850 kg/m³ Therefore, W = 3.14 x D²/4 x L x 7850 SAQIB IMRAN 0341-7549889 79 80 | P a g e But there are two conflicting unit in the formula. Those are millimeter for D and m for ρ (Rho). We have to convert either D or ρ to same unit. Let’s convert D from millimeter to meter. 1 millimeter = 1/1000 meter Lets implement this to the formula, W= 3.14 x D²/(4x1000x1000) x L x 7850 = D²L/162 Using this formula we can calculate the weight of steel bars. Calculating Weight of Steel Bars When Length is in meter Keep in mind that you always use D as millimeter and L as meter in this formula. Lets see some example. Example-1: How to calculate the weight of 100 meter long 16mm ø bar? In this example, D= 16mm L = 100 m SAQIB IMRAN 0341-7549889 80 81 | P a g e So, W = D²L/162 = 16² x 100/162 = 158 kg (approx) Answer: Weight of the 100 meter long 16mm ø bar is 158 kg. Example-2 How to calculate the weight of 100 m long 20mm ø bar? In this example, D = 20mm L = 100 m So, W = D²L/162 = 20² x 100/162 = 247 kg (approx) Answer: Weight of the 100 meter long 20mm ø bar is 247 kg. SAQIB IMRAN 0341-7549889 81 82 | P a g e Unit Weight of Steel Bar When Length is in Meter If you put 1 meter length for each diameter of steel bar in the formula then you’ll get the unit weight. Let’s see. W = D²L/162 Unit weight of, 10mm ø bar = 10² x 1/162 = 0.617 kg/m 12mm ø bar = 12² x 1/162 = 0.888 kg/m 16mm ø bar = 16² x 1/162 = 1.580 kg/m 20mm ø bar = 20² x 1/162 = 2.469 kg/m 25mm ø bar = 25² x 1/162 = 3.858 kg/m If you multiply the length of estimated bars with this unit weight you’ll get the total weight of steel bars for your reinforced concrete member. For example, total weight of 1000 meter long 25mm ø steel bar is, 1000 x 3.858 = 3858 kg. SAQIB IMRAN 0341-7549889 82 83 | P a g e So far we have seen the unit weight for each diameter of steel bar in meter basis. That means weight of bar per meter. But what if you estimate the steel bar length in foot. What will be the formula to calculate the steel bar’s weight if the length of bar is in foot? Calculating Weight of Steel Bars When Length is in Foot Again, Weight = A x L x ρ = 3.14 x D²/(4 x 304.80 x 304.80) x 222 = D²L/533 Where, D = Diameter of bar in mm (1 foot = 304.80 mm) ρ (Rho) = 7850 kg/m³ = 222 kg/ft³ (actually it is 222.287 kg/ft³) Keep in mind that you always should use D as millimeter and L as feet in this formula. Unit Weight of Steel Bar When Length is in Foot SAQIB IMRAN 0341-7549889 83 84 | P a g e If you calculate 1 foot length of any diameter of steel bar you will get the following result and that will be the unit weight of steel bars per foot length. Unit weight of, 10mm ø bar = 10² x 1/533 = 0.188 kg/ft 12mm ø bar = 12² x 1/533 = 0.270 kg/ft 16mm ø bar = 16² x 1/533 = 0.480 kg/ft 20mm ø bar = 20² x 1/533 = 0.750 kg/ft 25mm ø bar = 25² x 1/533 = 1.172 kg/ft If you multiply the estimated length of steel bars with these unit weights you’ll get the total weight of steel bars. For example, Weight of 1000 feet long 10mm ø bar is, 1000 x 0.188 = 188 kg. How to Estimate Materials for Isolated Footing Companies often use Software for estimating the project cost. They more often do this for biding purpose. But we are construction professionals and working on field level. So we can’t always use software for estimating materials for the small part of a building. Sometimes it is impossible to construct the whole part of a building at a time because of the critical condition of the project. SAQIB IMRAN 0341-7549889 84 85 | P a g e Let me clear this. Suppose, there are 30 numbers of isolated footing in a building. Whatever the reason, sometimes we can not make the all 30 numbers of footing ready for casting at a time. At that situation, we just make 3 or 4 numbers of footing ready for the casting. And it is not economical to cast this small quantity of concrete with readymix. So we always prefer machine mix concrete for this purpose. For constructing footing of a building you have to have plan before starting the task. You have to estimate the materials for footing. You have to make purchase requisition for materials and ensure the required materials are available on the project. The question is, what is isolated footing and what are the materials required for a isolated footing? Isolated footing is a shallow type footing. It normally holds one column on it. To know more about the types of footing read the following post – Materials Required for Isolated Footing For constructing a isolated footing following materials are required – Shutter Material MS Rod Binding Wire Cover Block and Chair Concrete SAQIB IMRAN 0341-7549889 85 86 | P a g e Shutter Material for Isolated Footing Most of the time wooden shutter materials are used for the isolated footing. Sometimes steel shutter materials are also used. We will use wooden shutter for this purpose, at least in this post. How to Estimate Wood for Shuttering Isolated Footing? See the above picture. The length of footing is 5 feet, width is 4 feet and height is 1 feet. To make the shutter for side-A of the footing you’ll need 4 feet long and 15 inches height wooden plank. SAQIB IMRAN 0341-7549889 86 87 | P a g e Our footing height is 1 feet. Then why we use 15 inches height wooden plank? Because we will fix the shutter below 3 inches from the bottom of footing. Then the required wooden shutter for side-A is, 4′ x 15″ = 5 sft (12″ = 1 feet, sft= square feet) We’ll use 1.5″ thick wooden plank. So the volume of the wood is, 5 sft x 1.5″ = 0.63 cft (cft= cubic feet) Wood is always measured as cubic feet. For the side-C we’ll require the same quantity of wood as side-A. Now, lets calculate the wood for side-B. Length of wood for side-B is, 5′-3″. But our footing length is 5 feet then why we’ll require 5′-3″ long shutter? Because we’ll join this shutter with the side-A’s and side-C’s shutter. The thickness of side-A and Side-C shutter is, 1.5″ + 1.5″ = 3″ Therefore, Length of side-B shutter is 5′-3″ or 63″ Width of side-B shutter is 1′-3″ or 15″ Thickness of shutter is 1.5″ SAQIB IMRAN 0341-7549889 87 88 | P a g e Then, volume of side-B shutter is, 63″ x 15″ x 1.5″ = 0.82 cft (cft= cubic feet). Side-D also require the same quantity of wood as side-B. So far, we have found – Required wood For side-A = 0.63 cft For side-B = 0.82 cft For side-C=side-A=0.63 cft For side-D=side-B=0.82 cft Total wood= A+B+C+D= 2.92 cft We will require 2.92 cft wood for making shutter for the isolated footing. If you don’t find required size of wood then you’ll need some 2″ x 1.5″ size wooden plank for making shutter. We estimated required wood for one isolated footing. If you have 30 isolated footing of different sizes calculate the required wood for each one using same technique we applied here. Total them all and make purchase requisition for the required wood. Now we’ll estimate the MS rod for the isolated footing. How to Estimate MS Rod for Isolated Footing? SAQIB IMRAN 0341-7549889 88 89 | P a g e See the above picture. There is a instruction for rod placement. That is 12mmØ[email protected]″c/c both way. It means 12mm diameter bar should be placed at the distance of 4″ centre to centre. The length of our isolated footing is 5 feet. The clear cover of reinforcement is 3 inches for one side. For both side it is 6 inches. So we have to place rod for 5′ – 6″=4.5′. Requires number of rods are, 4.5′ divided by 4″. That means 4.5’/4″= 13.63 numbers. Say 14 nos. You have to add one more number of rod for starting point. So total required number of rod is 14+1= 15 nos. Now we have to calculate the length of rod. We’ll place the rod along short-side (4′ side). So the length will be 4′ – clear cover of both side + hook (90 degree bend) length of both side. SAQIB IMRAN 0341-7549889 89 90 | P a g e = 4′ – 2×3″ + 2×6″ = 4′ – 6″ + 12″ (12″ = 1 feet) = 4.5′ So total length of all 15 numbers of bar is 15 x 4.5′ = 67.5 feet Now we’ll calculate the rod for long-side of the isolated footing. By following the above method, Number of rods, = 3.5’/4″ + 1 =11.61 Say 12 nos Length of rod, = 4.5′ + 1′ = 5.5′ Total length of rods for long-side of isolated footing, = 5.5′ x 12 SAQIB IMRAN 0341-7549889 90 91 | P a g e = 66 feet Total rods for the isolated footing = 67.5′ + 66′ = 133.5 feet. Say 134 feet You have to add 10% more rod with the estimated rod during ordering for purchase. You may not order rod as running feet. So you have to convert them in kilogram or ton. Oh. One more thing, you have to order rod for short column also. Because rebar of short column should be placed before casting footing. Summary of MS Rod Calculation For rods along short-side Numbers of rod= 4.5’/4″ +1= 14.64 say, 15 nos. Length of rod= 4′ – 6″ + 1’= 4.5′ Length of total rods=15 x 4.5=67.5′. For rods along long-side Numbers of rod= 3.5’/4″ + 1= 11.61 say, 12 nos. Length of rod=5′ – 6″ + 1′ = 5.5′. SAQIB IMRAN 0341-7549889 91 92 | P a g e Length of total rods=12 x 5.5=66′ Total rod for the footing= 67.5′ + 66’=133.5′ You’ll need a 10mm Ø bar for binding the main rod of the footing. The length of the binder is, 2 x 4.5 + 2x 3.5= 16′. So, total required rod is, 10mm Ø bar= 16′, and 12mm Ø bar= 133.5′ Binding Wire for Isolated Footing For binding rods you need binding wire. We need 9 kg to 13 kg binding wire for 1 ton of rod. You can estimate average 10 kg binding wire per ton of rod. So estimate total binding wire depending on required rod. Cover Block and Chair for Isolated Footing To keep the rod in place and maintaining concrete clear cover you should provide either cover block or chair for bottom and cover block for side. Cover block should be placed at 2 feet distance. You’ll need 8 numbers of cover block for sides and 5 numbers of cover block/chair for bottom of the Isolated footing. Concrete for Isolated Footing The size of our isolated footing, SAQIB IMRAN 0341-7549889 92 93 | P a g e Length – 5 feet Width – 4 feet Height – 1 feet. Volume of concrete for the footing is, 5x4x1 = 20 cubic feet. If you want to estimate ingredients for the footing first know the ratio of concrete suggested in the structural drawing. Then read the following post. I’ve just shown the estimating technique for one isolated footing here. You may have many footings of different sizes in your project. Follow the same technique to estimate materials for all the isolated footings of your project and sum up them to order materials for purchase. Some symbols and terms I used here in this post ‘– Foot symbol “ – Inch symbol Ø – Diameter symbol SAQIB IMRAN 0341-7549889 93 94 | P a g e 1′ = 12″ Sft – Square feet Cft – Cubic feet Nos – Numbers How to Estimate Concrete Volume for Grade Beam Grade beam is normally constructed on neck column and It connects two or more column together. In another word, grade beam carries the load from ground floor slab and transfer to column. Grade beam is normally constructed on ground. Purpose of this post is not to define what the grade beam is. I just giving some idea about grade beam so that newbie can understand the grade beam well. The purpose of this post is to show you how to estimate the concrete volume of grade beam. So let’s do this. Estimating Concrete Volume for Grade Beam SAQIB IMRAN 0341-7549889 94 95 | P a g e For estimating the concrete volume for grade beam you’ll need following structural drawing sheets. Grade beam layout Cross-sectional dimension of grade beam Column layout Cross-sectional dimension of column Grade Beam Layout: This sheet of structural drawing shows how to place grade beam on column. See the image below. In the above image, the grade beam layout just shows the grade beam number (GB1, GB2, etc.). It also shows the cross-sectional dimension that is 12″ x 20″. So you don’t need to look out for cross-sectional dimension of grade beam. You’ll get it from here. Column Layout: The grade beam layout we have in the above image doesn’t show the length of beam. If you want to calculate concrete volume of grade beam you’ll need it. So you’ll need to go to column layout for the length of beam. SAQIB IMRAN 0341-7549889 95 96 | P a g e See the image below. The above image is a column layout sheet of structural drawing. To get the grade beam length you have to calculate the distance between columns. I told before that you’ll also need the cross-sectional dimension of column for calculating concrete volume of grade beam. See the above image you’ll get this from there. Such as C1 (15″ x 45″), C2 (20″ x 45″), C3 (20″ x 35″), etc. So you don’t need any further cross-sectional dimension sheet for column. Are you still here? Then let’s estimate the concrete volume for grade beam. We’ll estimate concrete volume for GB1 shown in the 1st image. For estimating concrete volume of GB1 you’ll need following data – Cross sectional dimension of grade beam (GB1) Length of grade beam (GB1) SAQIB IMRAN 0341-7549889 96 97 | P a g e Cross sectional dimension of column (C1, C2 and C3) Height of column Cross Sectional Dimension of Grade Beam (GB1) From the grade beam layout sheet (1st image) you’ll find the cross sectional dimension of GB1. That is, 12″ x 20″. Length of Grade Beam Length of grade beam shows nowhere in grade beam layout sheet (1st image). sometimes it’s shown on the reinforcement detailing layout sheet of grade beam in structural drawing. You can also calculate the length of grade beam from column layout drawing sheet (2nd image). For finding the length of grade beam (GB1) you have to find the distance between C1 and C2 as well as the distance between C2and C3. Distance Between Column C1 and C2: For finding distance between column C1 and C2 you have to find the gap between grid-1 and grid-2. Then you have to deduct column portion inside the grid-lines. Let’s do this. Gap between grid line 1 and 2 is 24′-1″. Column portion inside grid-line1 and grid-line2: SAQIB IMRAN 0341-7549889 97 98 | P a g e C1 = 7½” C2 = 10″ So the distance between c1 and c2 is, = (24′-1″) – 7½” – 10″ = 22′-7½” Applying same process you can find the distance between c2 and c3. That is, = (18′-3″) + (5′-10″) – 10″ – 12½” =22′-2½” So the length of the grade beam (GB1) is, = 22′-7½” + 22′-2½” = 44′-10″ Therefore, the volume of grade beam is, = 44′-10″ x 12″ x 20″ = 74.87 cubic feet. Wait, we are not finished yet. SAQIB IMRAN 0341-7549889 98 99 | P a g e To get the concrete volume of grade beam you also have to estimate the concrete volume for column head. Column head is the portion of column which intersect with beam. Estimating Concrete for column head: In the 2nd image you’ll find three column heads connecting by the grade beam (GB1). So you have to estimate the concrete volume for these column heads also. Let’s do this. Cross Sectional Dimension of Column C1 – 15″ x 45″ C2 – 20″ x 45″ C3 – 20″ x 35″ So the area of the those three column heads are, (15″ x 45″) + (20″ x 45″) + (20″ x 35″) = 15.80 sft. Height of Column The height of all three column heads are same as height of the grade beam. That is 20″. SAQIB IMRAN 0341-7549889 99 100 | P a g e So the volume of column heads are, = 15.80 x 1.67 (20″= 1.67′) = 26.39 cft (cubic feet). So total concrete volume for the grade beam (GB1) is, = 74.87 + 26.39 = 101.26 cft. Following this process you can estimate the concrete for all grade beams of your project. If you want to cast the grade beams manually by mixture machine then you have to calculate required concrete ingredients for the volume of concrete. Read the following post to know how to calculate concrete ingredients. Summary Concrete volume for grade beam (GB1) only= Length x width x height = (22′-7½” + 22′-2½”) x 12″ x 20″ = 74.87 cft SAQIB IMRAN 0341-7549889 10 0 101 | P a g e Concrete volume for column heads = Area of column heads x height of column head = 15.80 sft x 20″ = 26.39 cft Total volume of concrete for grade beam (GB1) is, = 74.87 + 26.39 = 101.26 cft. Symbol and notation used in this post sft – square feet cft – cubic feet ‘ – foot ” – inch C1, C2, C3 – column symbol GB1, GB2, GB3 -grade beam symbol 4 Easy Steps for Making Column Stirrup SAQIB IMRAN 0341-7549889 10 1 102 | P a g e A rcc column has two types of bar. One is longitudinal bar and another ishorizontal bar. As horizontal bar we use stirrups and ties in column. Stirrup also has some other name in construction sector. Such as ring, shear reinforcement, etc. For making stirrup for column you have to calculate the cutting length of bar for stirrup, you have to calculate the number of stirrups and you have to determine the size of stirrup. You can do this in 4 easy steps. 4 Easy Steps for Making Column Stirrup Making column’s stirrup involves following 4 steps of work. 1. 2. 3. 4. Determine the size of stirrup Calculating cutting bar length for stirrup Calculating the number of stirrups Bending the bar in stirrup’s shape 1. Determine the Size of Stirrup SAQIB IMRAN 0341-7549889 10 2 103 | P a g e See the above image. The column size is 20″ x 40″. We know the concrete clear cover for reinforcement of column is 1½”. So the length of stirrup will be 40″-2×1½”=37″ and width will be 20″2×1½”=17″. So the size of the stirrup is 37″x17″. 2. Calculating Cutting-Bar-Length for Stirrup Before cutting the bar you have to calculate the cutting bar length for the stirrup. There are two terms – actual bar length and cutting bar length. The actual bar length of stirrup is, 2 x length + 2 x width + 2 x hook’s length = 2 x 37″ + 2 x 17″ + 2 x 3″ = 114″ or 9.5′. SAQIB IMRAN 0341-7549889 10 3 104 | P a g e Let’s discuss a little about hook length. Hook length is calculated by a formula that is 6db (diameter of bar). So the hook length for 10mmø bar is, 6 x 10 = 60 mm. But length of hook should not be less than 75mm (as per code). So the hook length for the stirrup is 3″ (75mm = 3″). The actual bar length of the stirrup is 9.5′. But the cutting bar length will be less than the actual bar length. See the above image. That is our stirrup. The stirrup has three 90° bend and two 135° hook. For each bend, the length of bar will be reduced. There is a certain formula to calculate the reduced length for bend. Below I’m giving a chart for reduced length for a 90° bend for different diameter of bar. SAQIB IMRAN 0341-7549889 10 4 105 | P a g e 10 mmø bar – 1″ 12 mmø bar – 1¼” 16 mmø bar – 1½” Since, we are using 10 mmø bar for our stirrup so the cutting bar length will be, 9.5′ – 3 x 1″ (bend deduction is ignored for 135° bend). = 9′-2″ So, you have to cut 9′-2″ length of 10mmø bar. That means, cutting bar length for the stirrup is 9′-2″. 3. Calculating the Number of Stirrups See the image above. There are two types of spacing for stirrups. One is S1 and another is S2. S1 is spaced 4″ c/c and S2 is spaced 8″ c/c. SAQIB IMRAN 0341-7549889 10 5 106 | P a g e S1 is provided in the bottom ¼th portion and top ¼th portion of clear column’s length. S2 is provided in the middle half portion of clear column’s length. Clear column’s length means the height of column between the top of floor to bottom of beam. You also should provide 2 numbers of stirrup for column into beamcolumn joint. Now let’s calculate the numbers of stirrups for column. The floor height is 10′. Beam height is 2′ Clear height of column is, = floor height – beam height = 10′ – 2′ =8′ Number of stirrups are, = 4’/4″ + 4’/8″ + 2 + 1 (1 bar should be added for getting the correct number of stirrups.) = 21 nos. SAQIB IMRAN 0341-7549889 10 6 107 | P a g e 4. Bending the Bar in Stirrup’s Shape You can use stirrup-making-machine for large project where vast quantity of stirrups are required. But, we often make stirrups by hand in our project. For making stirrups by hand you need a stand and a handle. See the above image. That is a hand-made stand and a handle. You can make stirrup with these tools. Just place the rod in the stand and bend the rod with the handle. You have to go for trial and error method to get the desired size of stirrup. Also don’t forget to make the hook angle at 135°. Symbol used in this post “ – inch ‘ – foot SAQIB IMRAN 0341-7549889 10 7 108 | P a g e ° – degree db – diameter of bar nos – numbers ø – diameter c/c – center to center distance Estimate the Neck Column’s Reinforcement With these 8 Easy Steps For complete estimating and costing solution of a construction project we always use computer aided software like Contractor’s office. It is time-saving and accurately deliver us what we want. But for our day to day construction activities, we always do this manually on the project to find the required materials for our tasks. In this post I’ll show how you can estimate the required reinforcement for neck column in 8 easy steps. As we know a neck column has two types of bars. One is longitudinal bar and another is stirrup. Longitudinal bars are those which are vertically places in column and stirrup are those which are horizontally provided around longitudinal bars. SAQIB IMRAN 0341-7549889 10 8 109 | P a g e So we’ll estimate both types of bars in following 8 easy steps. 8 Easy Steps to Estimate Neck Column’s Reinforcement Let’s start with the longitudinal bar first. 1. Determining the Number of Longitudinal Bar Summarise the numbers of same diameter bar separately. See the image below. There are different diameter of bars in the column section. Neck Column: Not scaled and designed From this image we have found 25mmø bar – 4 nos 20mmø bar – 6 nos 2. Determine the Length of a Longitudinal Bar SAQIB IMRAN 0341-7549889 10 9 110 | P a g e It is not practical to place the longitudinal bar more than 20′ long. Another thing to consider is that the full length of a bar is about 40 feet. If you cut them at middle you’ll get 20 feet long bar. So the length of longitudinal bar for the neck column is 20′. 3. Calculating total length of Longitudinal bars To find the total length of longitudinal bars multiply the length of each bar with the total number of bars of same diameter. Total number of 25mmø bar = 4 nos Total numbers of 20mmø bar = 6 nos Length of each longitudinal bar= 20′ Total length of longitudinal bars 25mmø bar= 4 x 20′ = 80′ 20mmø bar= 6 x 20′ = 120′ 4. Calculating the Weight of Longitudinal Bar To calculate the weight of bar you should know the unit weight of different diameter bar. Read the following post to know how to calculate the unit weight of steel reinforcement. From the above post, we found the unit weight of, 25mmø bar = 1.172 kg/ft, and 20mmø bar = 0.750 kg/ft. SAQIB IMRAN 0341-7549889 11 0 111 | P a g e Now multiply the total length of bar with unit weight to find the total weight of bar. 25mmø bar = 80 x 1.172 = 93.76 kg. Say, 94 kg. 20mmø bar =120 x 0.750 = 90 kg. Now let’s move for estimating stirrups of neck column. 5. Determining the Number of Stirrup To find the number of stirrup you need to know the length of neck column and the spacing of stirrups. The length of neck column is the distance between the top face of footing and the bottom face of grade beam. Let’s assume, neck column length is 5′. We can find the stirrups specification from the above image. That is 10mmø [email protected]″c/c. Now divide the neck column’s length with the stirrup’s spacing. That means, =5’/4″+1 (1 additional number should be added) =16 nos 6. Determine the Length of a Stirrup’s Bar The neck column size we found from the above image is 43″ x 23″. SAQIB IMRAN 0341-7549889 11 1 112 | P a g e That means, the length of column is 43″ and width of column is 23″. If we deduct the concrete clear cover from both side, the length of stirrup will be 43″-6″= 37″ and width is 23″-6″=17″. The length of bar for a stirrup is, 2 x length of stirrup + 2 x width of stirrups + 2 x hook’s length. = 2 x 37″ + 2 x 17″ + 2 x 3″ = 114″ [12″=1′] =9.5′ 7. Calculating Total Length of Bars for Stirrups To calculate the total length of bars multiply the numbers of stirrups with the bar length of a stirrup. Total numbers of stirrup = 16 nos Bar length for a stirrup= 9.5′ Total length of bars = 16 x 9.5 = 152′ 8. Calculating the Weight of stirrups To calculate the weight of stirrup’s bar just multiply the unit weight of 10mmø bar with the total length of stirrup’s bar. Unit weight of 10mmø bar = 0.188 kg/ft Total length of stirrup’s bar= 152′ Weight of stirrups bar= 152 x 0.188=28.58 kg, say 29 kg. So, the required steel reinforcement for the neck column is, SAQIB IMRAN 0341-7549889 11 2 113 | P a g e “25mmø bar = 94 kg 20mmø bar = 90 kg 10mmø bar = 29 kg” Symbol I used in this post ø – diameter of bar c/c – center to center distance ‘ – foot ” – inch ft – foot kg – kilogram nos – numbers How to Estimate Ingredients for 3″ Brick Masonry Wall? Masonry wall is the most common item in building construction. We use bricks for making masonry wall. The common size of brick is 9½”x4½”x2¾” inch. Most commonly used wall thickness in building construction are 3″, 5″ and 10″. We generally use cement-mortar for jointing bricks with one another. The ratio of cement-mortar, we use, for 3″ and 5″ thick wall is 1:4 and for 10″ thick brick wall is 1:6. SAQIB IMRAN 0341-7549889 11 3 114 | P a g e The ingredients or materials needed for making brick masonry wall are cement, sand and bricks. So, we have to estimate those materials. To estimate materials for brick masonry wall we need to know the thickness of mortar joint. We put half inch thickness of mortar between bricks for jointing. So our brick size with mortar thickness will be 10″x5″x3″. Now lets estimate the materials. Materials for 100 square feet 3 inch thick brick masonry wall – Area of one brick with mortar = 10″x5″ =0.83’x0.42′ = 0.35 square feet (as our wall is 3″ thick, so we’ll ignore the 3″ side of bricks for estimating bricks). Bricks needed for 100 sq.ft masonry wall are = 100/0.35 = 285.71 numbers, say, 286 numbers. If we take 5% wastage of bricks, then total bricks needed for 100 sq.ft 3″ thick masonry wall are = 285.74 + 5% = 300 numbers. SAQIB IMRAN 0341-7549889 11 4 115 | P a g e Now lets calculate the mortar volume – volume of 1 number of brick with mortar is = 10″x5″x3″= 0.83’x0.42’x0.25′ = 0.09 cubic feet (cu.ft). Without mortar volume of one number of brick is = 9½” x 4½” x 2¾”= 0.79′ x 0.38′ x 0.23’= 0.07 cu.ft. For 100 square feet (sq.ft) brick wall brick needed 286 nos excluding wastage. So, mortar volume for 100 sq.ft brick wall is = 286 x (0.09-0.07) = 5.72 cu.ft. Dry volume of mortar is 5.72×1.54 = 8.81 cu.ft, Including 5% wastage dry volume of mortar will be 9.25 cu.ft. As we use 1:4 cement-sand ratio for 3″ brick wall, so cement will be – cement = 9.25/5 = 1.85 cu.ft. 1 bag cement volume is = 1.25 cu.ft. So, cement needed 1.85/1.25 = 1.48 bag, say, 1½ bag. Sand will be needed for 100 sq.ft 3″ thick brick wall is =9.25/5 x 4= 7.40 cu.ft. Say, 8 cu.ft. Summary: Materials needed for 100 square feet 3″ thick brick wall are – SAQIB IMRAN 0341-7549889 11 5 116 | P a g e Brick – 300 numbers, Cement – 1½ bag, and Sand – 8 cu.ft. Practical estimation: The above estimation of 100 sq.ft 3″ thick brick wall is correct. But practically I found that the required sand quantity is 10 cu.ft. So, it’ll be better to calculate the required materials for 100 sq.ft 3″ thick brick wall by following manner – Cement – 1½ bag, Sand – 10 cu.ft, and Brick – 300 NOS. How to estimate materials for different quantity of 3″ thick brick wall? Suppose you need to calculate the required materials for “Y” sq.ft 3″ thick brick wall. You can do this by following way – Cement – Y x 0.015, Sand – Y x 0.10, and Brick – Y x 3. How to calculate materials for differentratio concrete SAQIB IMRAN 0341-7549889 11 6 117 | P a g e Stone chips Now-a-days, most of the modern construction company use computer aided software like priosoft for their complete estimating and costing solution. But for on-site job execution we often estimate materials ourselves. Mix design is commonly referred by mix proportion in a selective zone where same materials are used in concrete. Suppose, in Bangladesh, most of the structural designers refer concrete mix design as ratio in drawing. Because materials of same properties are used in all over the Bangladesh. The question is, How Do We Estimate Materials for Different Ratio Concrete? SAQIB IMRAN 0341-7549889 11 7 118 | P a g e The most common ratio referred here in Bangladesh for column concrete 1:1.5:3 and for slab 1:2:4. When we mix cement, sand and stone chips at 1:1.5:3 ratio, the concrete strength of 28 days cube test’s result comes around 3500 psi. If we mix cement, sand and brick chips at 1:2:4 ratio the 28 days cube test result will come around 3000 psi, which is referred for slab concrete. I will estimate materials for 1:1.5:3 ratio concrete. After learning this process you will be able to estimate materials for any concrete ratio. Now lets estimate the required materials for the volume of 100 cft concrete of 1:1.5:3 ratio: Wet volume of concrete = 100 cft. Dry volume of concrete= 100 x 1.54 = 154 cft. Sum of ratio 1:1.5:3, 1 + 1.5 + 3 = 5.5. So, Cement content in concrete = (154/5.5) x 1=28 cft. Sand content= (154 / 5.5) x 1.5 = 42 cft. Stone chips = (154/5.5) x 3 = 84 cft. As we know, Cement is available as 50 kg bag in the market. The volume of 50 kg cement bag is 1.25 cft. So the required cement is 28 divided by 1.25 equal to 22.4 bag. Summary: Cement : 22.4 bag, Sand : 42 cft, Stone chips: 84 cft. SAQIB IMRAN 0341-7549889 11 8 119 | P a g e In this estimation, we use cubic feet as our concrete unit. If you want to use cubic meter, same method can be applied. But that will be timeconsuming. The easiest way to estimate concrete materials for different unit is, apply the above result as percentage. That means, Cement content for 100 unit of 1:1.5:3 ratio concrete is 28% (unit will be as concrete unit), Sand is 42% and Stone chips is 84%. Now lets calculate the water content of concrete. Suppose, watercement ratio for concrete is specified 0.45. That means, water/cement = 0.45, or W/C = 0.45. for 1 bag cement, water is, = 0.45 x 1.25 (as we know, 1 bag cement equal to 1.25 cft), Water = 0.5625 cft. We know 1 cubic feet water is equal to 28.31685 litre, So we can write, water = 0.5625 x 28.31685 = 15.92 litre, say, 16 litre. So One bag cement needs 16 liter of water for 0.45 W/C ratio. That’s it. Here, one thing should be cleared that someone assume the dry volume of concrete is equal to one and half times of wet volume. But it is better to use 1.54 for calculating dry volume. How to Estimate Materials for 5″ Thick Brick Wall Brick wall is used to separate a floor in a different usable space. Such as bed room, living room, toilet, kitchen, store etc. We use different thickness of brick walls for this purpose. The thickness can be 3 inch, 5 inch and 10 inch. We normally make 10 inch SAQIB IMRAN 0341-7549889 11 9 120 | P a g e thick brick wall at periphery and 5 inch thick brick wall as internal partition wall. Whatever you are, a house owner, a civil engineer, a construction supervisor, a civil contractor or a builder, you should estimate the required raw materials for the brick walls which you plan to build. In this post i’ll show you how to estimate the required raw materials for 5 inch thick brick wall. The raw materials we use to make brick wall are brick, cement and sand. Lets take a 10 feet long and 10 feet high brick wall for our estimation project. Then, area of our wall is, 10′ x 10’= 100 square feet. As our wall thickness is 5 inch, so the wall’s volume is, 100 sft x 5 inch =41.67 cft (5″ = 0.42) As we know, we make the masonry brick wall with cement-sand mortar. The ratio of the mortar we use for 5 inch thick brick wall is 1:4. You should read the following posts to know more about this – The brick size we use to make brick wall is 9.5″ x 4.5″ x 2.75″ which will be 10″ x 5″ x 3″ after jointing with mortar. Volume of one brick with mortar is, 10″ x 5″ x 3″ =0.08715 cft. (1 inch = 0.08 feet) So, the required bricks for our wall are, wall volume divide by one brick volume. That is, SAQIB IMRAN 0341-7549889 12 0 121 | P a g e 41.67/0.08715 =478 nos. These are required bricks for our wall. Now, we’ll estimate required mortar. If we deduct the volume of unmortared brick from our wall volume, that is our mortar volume. Lets see – Wall volume is 41.67 cft, Total brick volume (excluding mortar) is, 478 x 9.5″ x 4.5″ x 2.75″ =32.52 cft. So, the mortar volume is, 41.67-32.52 =9.15 cft. This is the wet volume of mortar. The dry volume of mortar is, 9.15 x 1.50 = 13.73 cft. As we know, cement-sand ratio is 1:4, then cement content in dry mortar is, 13.73 /(1+4) x 1 = 2.75 cft As cement is measured by bag and we know 1 bag contains1.25 cft cement so, 2.75 cft cement equal to 2.75/1.25= 2.20 bag cement. If we deduct cement volume from dry mortar volume then we will get sand volume. That means, 13.73 – 2.75= 10.98 cft. Required materials for 10′ x 10′ brick wall, we found – Brick – 478 nos, we can assume this 500 nos. Cement – 2.16 bag, we can assume this 2 bag. Sand – 10.98 cft, we can assume this 11 cft. That’s it. Here is full calculation process, Wall volume, 10′ x 10′ x 5″=41.67 cft (5″ = 0.42, cft means cubic feet). One brick volume with mortar, 10″ x 5″ x 3″ =0.08715 cft. (1 inch = 0.08 feet) Required brick, SAQIB IMRAN 0341-7549889 12 1 122 | P a g e 41.67/0.08715 =478 nos, Total brick volume (excluding mortar) is, 478 x 9.5″ x 4.5″ x 2.75″ =32.66 cft. Wet volume of required mortar is, 41.67-32.52 =9.15 cft. Dry volume of mortar is, 9.15 x 1.50 = 13.73 cft. cement content in dry mortar is, 13.73 /(1+4) x 1 = 2.75 cft 2.75/1.25=2.20 bag cement. Sand volume, 13.73 – 2.75= 10.98 cft. Types of Estimates in Building Construction Estimation determines the probable construction cost of a project. Estimating can be done at various stages of project duration depending on the purpose of estimation. First estimation is done before construction starts for the purpose of making budget of the project or bidding the project as a contractor. There are various types of estimation can be done depending on project manual and drawing SAQIB IMRAN 0341-7549889 12 2 123 | P a g e provided and the purpose of using estimated data. Types of Estimates in Building Construction Followings are common types of estimate – * Detail Estimate * Unit Based Estimate * Model Estimate * Comparison Estimate SAQIB IMRAN 0341-7549889 12 3 124 | P a g e * Parametric Estimate Detail Estimate – This type of estimate includes everything that needs to complete the project as well as overhead and contractor’s profit. For this type of estimate, an estimator needs complete set of drawing and instruction manual of the project. This estimate shows required materials, labor, time to complete the project, complete cost details and overhead and also contractor profit. It also includes insurance, bond, equipment and other necessary things that need to complete the project. Estimator for this type of estimating should be experienced person because complete project budget, time duration and contractor profit depends on his visualization. Unit Based Estimate – This type of estimate is prepared by calculating building area and then multiplying area by predefined unit cost. And then adjusted the cost by considering building height, length, width and other necessary building components. Required documents for preparing this type of estimate is a simple floor plan with measurement and key elevation of the building. This type of estimation is used to check whether the project was designed within owner’s budget. Model Estimate – This type of estimate is prepared based on a model project estimate which is developed before. Preparing this type of estimate needs answering several key questions depending on model project. Such as length and width of building, number of base, size of base, floor height, number of bath etc. Keep in mind that proposed project should be similar to model project. this type of estimate may prepare a details estimate of whole project or a part of project depending on the model project. SAQIB IMRAN 0341-7549889 12 4 125 | P a g e Project Comparison Estimate – In this method, an estimator prepares estimate of proposed project by comparing similar completed project. After preparing the comparison estimate, estimator makes adjustment for variation of proposed project with the completed project. Parametric Estimate – In this type of estimate, an estimator uses equations to prepare the estimate. This equation is the relationship between “parameters” and “cost” of a building project. This estimate is like unit based estimate but more complex than unit based estimate. This type of estimate is done for getting concept of proposed project cost. There are some other methods are used to determine the project cost in the different location of the world. Nowadays, there are many computer programs available in the market to make the estimation process easy and quick. Estimation, Costing & Quantity Surveying What is Check measurement book Check measurement book is maintained by the sub-divisional officer with the sole purpose of checking at least 25% of the measurements made by junior engineer. Main items of work involved in construction Main items of work involved in construction are : (a) Earth work (b) R.C.C. and R. B. work (c) Flooring (i) Ground floor (ii) Upper floor (d) Roof (e) Plastering and Pointing (f) Doors and windows (i) Frame work (ii) Levers and shutters for doors or windows (g) Iron work SAQIB IMRAN 0341-7549889 12 5 126 | P a g e (h) White washing or Distempering (i) Painting What is Measurement book Measurement book is a note-book in which measured entries regarding the work done or supplies made are recorded. It is then used for the purpose of making payments to the contractor. This is one of the most important book and is maintained by the junior engineer. What is Standard measurement book Standard measurement book is a measurement book of permanent nature. In it detailed measurements of a building are correctly recorded on its completion so as to facilitate preparation of estimates for periodic repairs. For annual white washing, painting etc. payment to the contractor is made on the basis of this book after preparing the bills. Tools and plants (T and P) : In big project a percentage of 1% to 1 1/2% of the estimated cost is provided for the purchase of tools and plants which is required for the execution of the work. Explain Estimation and its Objectives Estimation : An estimation is a record of computation of the quantities of materials and items of work required and expenditure likely to be incurred in the construction of building, road, dam etc. Objectives of Estimating : 1. To find probable cost of the work. 2. To find the quantity of various materials and labour required. 3. To have an idea about the time of completion of the work. 4. To help in controlling of the expenditure during execution. 5. To help checking the work done by contractors. 6. To help in completion of departmental formalities such as inviting tenders, technical sanction etc. 7. To help in the fixation of standard rent, sale price of flats and valuation of properties. Materials For Different Works Materials For Different Works : SAQIB IMRAN 0341-7549889 12 6 127 | P a g e Describe Specification Specifications describe the nature and the class of work materials to be used in the work standard of workmanship desired etc. specification should be clear and there should not be any scope for ambiguity. (a) General specifications : These give the nature and class of work in general terms to be used in the various parts of the work. from the foundation to the super structure. (b) Detailed specifications : Detailed specifications of an item of work specify the quality and quantity of material, the proportions of mortar, the method of preparation and execution, workmanship etc. Detailed SAQIB IMRAN 0341-7549889 12 7 128 | P a g e specifications are written to express the requirements clearly in a concise form avoiding repetition and ambiguity. These usually form a part of contract. Task Work or Out-Turn Task Work or Out-Turn SAQIB IMRAN 0341-7549889 12 8 129 | P a g e SAQIB IMRAN 0341-7549889 12 9 130 | P a g e Types of Estimate Various types of estimates are 1. Rough cost estimate : It is prepared to decide the financial policy matter. It is prepared on the basis of practical knowledge and cost of similar works. The competent sanctioning authority accords 'Administrative approval'. 2. Plinth area estimate : It is prepared on the basis of plinth area of a building multiplied by plinth area rate prevalent in the region. Plinth area rates are fixed from the cost of similar buildings constructed in the locality having similar finishing and amenities. 3. Cubical content estimate : This estimate is worked out on the basis of the cubical contents of the proposed building to be constructed and then applying to it the rate per cubic metre. This is more accurate than plinth area estimate. The cubic content rates are deduced from the cost of similar buildings constructed in the same locality. 4. Detailed or Item rate estimate : This estimate is an accurate one and is based on the plan and sanctions of the building. The quantity of items under each sub-head of work are calculated from the dimensions taken from drawing and then total cost is worked out in a form called abstract of cost. 5. Revised estimate : It is also a detailed estimate and is prepared a fresh when the original sanctioned detailed estimate exceeds by 10% or more, either due to the rates being found insufficient or due to some other reasons. 6. Supplementary estimate : This is a fresh detailed estimate of the additional work in addition to the original one and is prepared when additional work is required to supplement the original work. 7. Repair and maintenance estimate : In order to keep the structure, roads etc. in proper condition annual repairs are carried out annually for which an estimate is prepared. The estimated amount should not be more than 1.5% of the capital cost of the work. SAQIB IMRAN 0341-7549889 13 0