Chapter 3
Measuring Quantities Generally
Objectives
• Upon completion of this chapter, you
will be able to:
– Define the quantity takeoff process
– Explain the process of measuring “net in
place” and why this process is adopted
– Describe how takeoff items are composed
– Discuss the level of accuracy required for a
takeoff
Objectives (cont’d.)
– Discuss the use of assemblies in the
takeoff process
– Discuss the role of computers in the takeoff
process
– Calculate the area of regular and irregular
plane shapes
– Calculate the volume of a variety of solid
figures
Objectives (cont’d.)
– Given the dimensions of a building plan,
calculate the centerline length of the
perimeter trench/footings/wall
The Quantity Takeoff
• Process of measuring work
– Series of quantified work items
•
•
•
•
Design is broken down
Items are measured according to rules
Standard format enables easier evaluation
Method of measurement can be shared
What Is Measured?
• Takeoff: work quantities are measured
– Not material quantities
• Quantity takeoff for cost estimate
– Measurements are made “net in place”
– Provides sufficient pricing information
– Includes items that don’t involve materials
Units of Measurement
• Two systems in North American
construction
– English system
– Metric system
• Estimators are advised to work entirely
in one system
– Mixing increases probability of error
Item Units
• Basic categories:
– Number
– Length
– Area
– Volume
– Weight
Measuring “Net in Place”
• Quantities are calculated using sizes
and dimensions
– Indicated on drawings
– Reasons:
•
•
•
•
Consistency
Objectivity
Unit price contracts
Comparisons of operation efficiencies
Takeoff Rules
• Takeoff item components:
– Dimensions
• Define the size or quantity
– Descriptions
• Classifies the item
• To be effective, preserve flexibility
– While keeping pricing and efficiency in
mind
Accuracy of Measurement
• Quantity takeoff
– Should accurately reflect amount of work
• Level of accuracy pursued
– Depends on costs and benefits of attaining
high accuracy
• Extra time may not be justified
• Must be balanced
Organization of the Takeoff
• Generally follows sequence of work
activities
– Contract drawings usually presented in this
sequence
• Measure concrete before excavation work or
• Begin with excavation measurement
– Assemblies: component considered
separately
• Distinguished after project is divided into parts
Estimating Stationery
• Specially printed forms
– Designed for each estimating procedure
• Used to increase productivity
• Contributes to accuracy of estimate
– Number of different formats
• Quantity takeoff
– Recapped onto separate sheets for pricing
• Takeoff and recap
Figure 3.3 Sample Pricing Sheet
(Delmar/Cengage Learning)
Figure 3.4 Stationery for Combined Takeoff
and Pricing (Delmar/Cengage Learning)
Formulas/Perimeter Centerline
Calculations
Figure 3.5 Perimeters and Areas of Plane Shapes
(Delmar/Cengage Learning)
Figure 3.6 Volumes of Solid Figures
(Delmar/Cengage Learning)
Figure 3.7 Plan and Section of Wall
Figure 3.8 Plan of Corner of Wall
(Delmar/Cengage Learning)
(Delmar/Cengage Learning)
Figure 3.9 Plan and Perimeter
Calculation of Wall (Delmar/Cengage Learning)
Figure 3.10 Plan of Exterior/Interior
Corner (Delmar/Cengage Learning)
Figure 3.11 Wall Plans
and Perimeter
Calculations
(Delmar/Cengage Learning)
Figure 3.12 Wall Plans and
Perimeter Calculations
(Delmar/Cengage Learning)
Summary
• Quantity takeoff
– Process of measuring work of a project
• In the form of a list of quantified work items
– Uniform rules
• Contained in “measuring notes”
– Order of takeoff
• Follows construction sequence