CONSTRUCTION BLUEPRINT READING
GRID LINES AND KEY PLANS
1
CONSTRUCTION BLUEPRINT READING
Grid lines are a very important component on
blueprints, especially for large construction
projects.
They will appear on the structural, architectural
and electrical drawings.
These grid lines are similar to the grid lines
used on road maps and serve the same
purpose, to locate a specific area on the project.
2
CONSTRUCTION BLUEPRINT READING
On one side of the drawing a series of numbers will
be present with connecting lines attached to the
perimeter of an object and passing through to the
other end.
On the top or bottom of the drawing a series of
letters will be present.
The combination of a letter and a number is used to
pin point a specific location on the drawing.
3
CONSTRUCTION BLUEPRINT READING
Foundation plan showing grid lines:
4
CONSTRUCTION BLUEPRINT READING
When looking at the I-beams on a drawing
you will notice that there are all typically
spaced the same distance apart.
Normal spacing between I-beams is 20’ to 25’,
knowing that can enable you to do quick
length calculations for cable footages and
device placements.
5
CONSTRUCTION BLUEPRINT READING
The I-beams along the top are spaced 18’ apart.
6
CONSTRUCTION BLUEPRINT READING
Grid lines typically line up with the I-beams
on a project, each I-beam will have either a
letter or number designation and they are
spray painted onto the I-beams.
This method of using lines allows contractors
contractors to indicate half way points
between grid numbers and letters, i.e.
7
CONSTRUCTION BLUEPRINT READING
In many cases certain letters and
numbers are omitted from the grid line
system to avoid confusion.
0, 1, I, O, and Q are usually omitted form
the grid line system.
8
CONSTRUCTION BLUEPRINT READING
Using the grid lines, where is the center of the TR located?
APPROX. M.3 X 2.8
9
CONSTRUCTION BLUEPRINT READING
WHAT IS LOCATED AT L.5 X 2.5?
FLOOR MOUNT ELEC./ V&D OUTLET
10
CONSTRUCTION BLUEPRINT READING
By using the prints and looking at the
numbers and/or letters on the steel columns
you can orient yourself on site.
Grid lines along with the north symbol will
frequently be used to identify spaces and
parts of the building.
In the previous slide the electrical room and
telecom room are located on the east side of
the building.
11
CONSTRUCTION BLUEPRINT READING
On large construction projects it’s necessary to
cut a building up in sections so that they will
fit on a drawing sheet.
To do this architect's use a key plan that will
appear in the drawing area of every plan, the
purpose of the key plan is to identify that part
of the project to which the sheet applies.
12
CONSTRUCTION BLUEPRINT READING
The un-shaded portion of the key plan appears on
other drawings, the shaded section of a key plan is
the portion of the project represented on the drawing
sheet that you’re looking at, in some case the shaded
portion may be represented by cross hatched marks
instead of shading.
13
CONSTRUCTION BLUEPRINT READING
This project has four different sections; A, B, C and
D, this means that there is a full set of blueprints for
each section all included in the original roll of
blueprints.
There will be a match line that separates each section
and there is a little overlap from one section to the
other.
14
CONSTRUCTION BLUEPRINT READING
The key plan indicates that you’re looking at section D
15
CONSTRUCTION BLUEPRINT READING
As you move from section to section pay close
attention to the match line.
If you’re counting locations for a material count
remember that there is overlap between sections so
you could easily double count items.
That means you will have to compare two sets of
drawings for accuracy.
16
CONSTRUCTION BLUEPRINT READING
WHERE IS THE MATCH LINE LOCATED?
H.4
17
CONSTRUCTION BLUEPRINT READING
WHY IS THE GRID LINE SYSTEM
MISSING THE “1” AND THE “I”?
18
CONSTRUCTION BLUEPRINT READING
During the course of a project many changes
will be made both small and large, when this
occurs an addendum will be generated.
An addendum is an official document that
describes the changes to take place, this might
mean moving a wall 1 foot or turning an office
into a storage room.
19
CONSTRUCTION BLUEPRINT READING
Addendums will include a NTS drawing showing the
changes to take place and a scope of work to be done.
The addendum will indicate the area to change using
the grid line system and will be signed off by the
architect or general contractor.
The addendum becomes an official legally binding
document and should be treated as such.
20
CONSTRUCTION BLUEPRINT READING
Conversely, if you notice a discrepancy with a
section of the building your working in, or if
just need clarification with a section of the
drawings you can generate an RFI (request for
information).
You will need to indicate what part of the
building your requesting info for and the best
way to do that is using both the key plan and
grid line location.
21
CONSTRUCTION BLUEPRINT READING
Based on the information provide which section is
the work on this projected been done in?
Is it the North, South, East or West wing?
SECTION “D”
WEST WING
22