Introduction
To
Blue Prints
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What is a 'blueprint'?
Originally, 'blueprint' was a term that referred to a method of reproducing a drawing. This process
created an exact duplicate with all lines being blue. Although blueprints are still used, the
technology of computers and printers make it uncommon. Sets of drawings are often reproduced on
a 'bond' paper which is black on white. Generally, the word 'blueprint' is now used to refer to these
copies of drawings, rather than the actual blue line prints.
How do I read a blueprint?
The first thing to consider when reading blueprint is scale. Every drawing in a set of plans should
have a scale, which can be defined as a ratio of distance. For example, a plan can be reduced to
1/8"=1'0" which means that for every 1/8" measured (on the drawing) it represents 1'0" in reality.
The drawing has been scaled down to fit on the paper. As you can see, it would be impossible to
draw plans without these ratios. There are two types of scales: Architectural and Engineering.
Architectural scales units are based on foot/inch dimensions. Floor plan drawings are usually drawn
to the scale of 1/4" = 1'-0". For a very large plan, a scale of 1/8" = 1'-0" may be used. When
drawing a small plan or a single room, scales of 3/8" = 1'-0", 1/2" = 1'-0", 3/4" = 1'-0", or 1" = 1'-0"
may be used to fit the size of your drawing format. Engineering scales units of measure are equal
to parts per inch and parts per foot. The most common graduations are 10, 20, 30, 40, 50, 60 parts
per inch, but there are scales available that have 100, 200, 300, 400, 500, 600 parts per foot. The
graduations vary upon the application.
Metric Scales - metric measurements is the standard in most of the world. The principles are
similar. You have to get used to measurements expressed in meters (m) and millimetres (mm). One
meter is slightly larger than one yard. A millimetre is 1/1000 of a meter. Metric scales are usually
based on ratios. A ratio is the relationship of one measurement to another. For example, metric plot
plans are often drafted in ratios of 1:100. This scale is very close to the scale 1/8" = 1'-0" (1:96).
Metric floor plans are drawn in a ratio of 1:50. This is very close to a scale of 1/4" = 1'-0" (1:48).
Construction details may be drawn to metric scales of 1:20, 1:10, or 1:5. It should be noted that all
dimensions in metric dimensions are in millimetres. Therefore, it is not necessary to use the symbol
mm. Although both serve to assist in measuring distance in a drawing, they have some differences.
Metric and Engineering scales are very similar in appearance, if a metric scale is used on a drawing
that has been reduced or enlarged with a civil engineers scale the tradesperson will be provided
with incorrect measurements. Metric Rules of thumb:
1 mm = about 1/25 inch = thickness of a dime
25 mm = about 1 inch (1” = 25.4 mm)
300 mm = about 1 foot (12” = 304.8 mm)
1000 mm = 1 metre = about 3 feet + 10% more (very roughly a yard)
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Architectural Scale: ¼ = 1
Engineering Scale: 1 = 50
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What are some of the symbols?
Within any technical drawing, you will find many different symbols. Although architects,
engineers, drafters, and contractors will have their own versions of these symbols, they will still
function consistently with the standards listed below:

Detail Designation
These are used to indicate the location of an enlarged detail in order to show more information
than what appears in the current drawing. They are also used to highlight the area of the house
that is being enlarged.

Section Mark
These are used to indicate that there is a drawing showing the house cut at that point. This cut is
to show the insides of the house, including the structure and all the inside elements.
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
Elevation Detail Symbol
These are used to indicate a drawing of what an area will look like from a straight on view. These
drawings are usually meant to show heights, interior and exterior features and design intent.

Elevation Mark
These are used to indicate the height of a particular object. An elevation mark is normally found
on a Reflected Ceiling Plan (a drawing looking up at the ceiling) or an Elevation Drawing, interior
or exterior, and is usually attached to a number.
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
Title
The title mark reveals the detail number, sheet location, and a title. The title will usually be
descriptive of the detail.

Center Line Symbol
Center line symbols are used to indicate that something is either dimensioned to a center line of
a wall or an object.

North Arrow
A north arrow does exactly what you'd expect: it indicates which direction is north. This
symbol is most commonly found on site and floor plans. Keep in mind on blue prints true north
is shown as well as something called construction north. Construction north shows the most
north of a building and designates that north, this allows for easy reference in a building for
direction since most buildings are built symmetrical. Though it can be found in many different
styles and versions, below is the most common:
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What are the various drawings and their functions?

Site Plan:
A site plan should be drawn first, and should appear first in the final set of drawings. There
is a great deal of information on a site plan that is vital to your project. The site plan will
show everything from code issues to landscaping, and most importantly the location of the
building on the site. Some specific functions you will find on a site plan are drainage
(contours of the site), trees and other landscape elements, setbacks, and property lines.
Show outdoor lighting, the location of utilities and there connection points and easements
(rights of the property by somebody other than the owner.

Floor Plan:
The floor plan is the drawing that governs the design of the house. Floor plans usually
require the most attention by the designer and show the overall layout of entrances, rooms,
windows, and any special features. Floor plans are actually quite easy to understand. A floor
plan layout on blueprints is basically an overhead view of the completed house. You'll see
parallel lines that scale at whatever width the walls are required to be. Dimensions are
usually drawn between the walls to specify room sizes and wall lengths. You'll also see on
the floor plan locations of fixtures like sinks, water heaters, furnaces, etc. Among the walls
and dimensions you will often find notes to specify finishes, construction methods, or even
symbols for electrical or to reference cross sections. You will probably also notice a number
of circles, triangles, or hexagons with numbers inside of them. Placed next to windows and
doors — and sometimes next to other elements, such as lighting or plumbing fixtures —
these notations correspond to those on the window, door, plumbing, and electrical schedules
found at the back of the blueprints. These schedules indicate the size and types of the doors
and windows to be used, and sometimes even the manufacturer and model numbers, as well.
Usually on complex jobs the Architectural, electrical, mechanical, plumbing, HVAC
(Heating, Ventilating, and Air conditioning) and Structural will be on separate sets of
drawings for each. This allows each individual trade to concentrate on there specific
function allowing each other to cross reference each others sets of drawings to divert
conflicts.

Building Sections:
These drawings are cross-sections of the house. They allow the reader to view the house as
if it were cut in half. This type of drawing is important for the architect to determine if there
will be any design issues or conflicts. For the contractor, this drawing provides visual cues
on how to proceed with the construction. Finally, for the owner, this plan will help in
visualizing the finished product. Floor plans use section marks to indicate a building
section.
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
Wall Sections:
Wall sections are similar to building sections except they are only intended to show the
construction of one exterior wall. These drawings usually appear at a larger scale so that
more detail can be included. As with building sections, a wall section is indicated on the
floor plan with a section mark.

Exterior Elevations:
As with floor plans, the Elevation drawings are vital in modeling the design of the job.
Elevation plans will document any exterior features, such as decks and porches. They will
also reveal window and door locations, eave heights, and roofing dimensions. The elevation
plans should always be included in the set of drawings, and are referred to by the elevation
detail symbols on the floor plans. Elevations are a non-perspective view of the home. These
are drawn to scale so that measurements can be taken for any aspect necessary. Plans
include front, rear and both side elevations. The elevations specify ridge heights, the
positioning of the final grade of the lot, exterior finishes, roof pitches and other details that
are necessary to give the job its exterior architectural styling.

Interior Elevations:
Interior elevations are intended to show the design elements of the interior. They could
indicate finishes, trims and colors. Specific heights of plugs, lights etc… An elevation detail
symbol is used to reference these drawings.

Reflected Ceiling Plan:
The purposes of these drawings are to reveal the lighting layout and any ceiling conditions.
Exact locations of pot lights, where fixtures need to be placed in dropped ceilings, types of
ceilings either being exposed or covered.

Details:
Within a set of drawings, there will be many areas that need further detail. Using a drawing
at a larger scale, this can be accomplished. The details are indicated with a detail
designation symbol. Overhead views or floor plan views of the structure don't always
provide enough information on how the home is to be built. Often time’s cross section or
details will explain certain special conditions more appropriately. A cross section is
basically a view of the job if it were sliced down the center. This allows you to view the job
from the side and understand a little better the relativity of varying floor heights, rafter
lengths, and other structural elements. Also showing details of kitchen cupboards and
bathroom vanities and anything that requires a closer look.

Electrical Layout:
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Electrical layouts are sometimes on a separate page to make reading them a little easier. The
layout will show locations of light fixtures, fans, outlets, light switches etc. There is also
usually a riser diagram showing main distribution and any required conduits or
requirements from the Telephone or cable local utilities. There is usually a legend on the
first page which explains what each symbols represents.

Specifications:
Specifications give precise information to all trades involved in the project, that should be
incorporated into the drawings. They are written descriptions of materials, specific heights
and manufactures that the owner or architect would like the trades to use. Usually
specifications are part of the bid, where any “allowances” - which are lump sums of money
for standard materials/fixtures – are listed and should be followed by all contractors biding
for the job. Information like electrical sizes, rating of equipment, brands, etc is usually
written here, as well as height restrictions for any installation from plugs to switches.
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