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IC Training Modules Construction Drawing Practices IC PROFESSIONAL TRAINING SERIES Last updated at AUGUST 2009
Copyright reserved by INDUSTRIAL CENTRE, THE HONG KONG POLYTECHNIC UNIVERSITY
Construction Drawing Practices
Cons truction Drawing P ractices
Objectives:
9
9
To provide the students with knowledge of principles and techniques of
manual construction drawing
To enable them to appreciate the use engineering drawings as a
communication medium in the construction industry.
Upon completion of the subject, students will be able to:
a. Prepare basic sketches, orthographic projections and working drawings.
b. Apply drawing standards and conventions.
c. Produce a construction drawing for structural concrete to recognized
construction drawing standards.
d. Produce a construction drawing for structural steel to recognized
construction standards.
e. Produce simple construction CAD drawing with MicroStation.
f.
Communicate using engineering drawings as media.
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IC Professional Training
Construction Drawing Practices
TABLE OF CONTENT
1.
Introduction
2.
Drawing Lines and Shapes
3.
Drawing to Scale
4.
Lettering and Dimensioning
5.
Graphic Conventions
6.
Orthographic Projection
7.
Pictorial Views (3D)
7.1
7.2
7.3
8.
Isometric Projection
Perspective Projection
Oblique Projection
Construction Drawings
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
Site Plans
Floor Plans
Sections
Elevations
Assembly Drawings
Component Drawings
Structure Engineering Drawings
Service Drawings
Freehand Drawings
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IC Professional Training
Construction Drawing Practices
1
Introduction
Construction drawing is a means of showing in a graphical form the shape, size
and position of a building on a site, together with the composition of the
materials used and the way the building is to be constructed or put together. The
information on construction drawings has to be presented in a precise,
unambiguous way so that it can be understood by anyone with a knowledge of
draughtsmanship and construction.
It should be borne in mind that the contractor’s staff using the drawings on a
construction site often work under difficult circumstances, and the quality and
clarity of the drawings should reflect this fact.
The term ‘construction drawing’ includes not only drawings produced by
architects, which generally make up the majority of the drawings for a building
project, but also structural drawings which are the province of structural
engineers, and building engineering services drawings which are commonly
prepared by building services engineers.
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Construction Drawing Practices
2
Drawing Lines and Shapes
GETTING STARTED
At this stage you should have the following equipment to assist you.
•
•
•
•
•
•
•
•
•
Sheets of A2 cartridge paper
A2 drawing board and tee-square
Drafting tape
Fine-lead mechanical pencils with H and HB leads
Two technical pens, one for drawing lines 0.3mm thick and the other for
drawing lines 0.7mm thick.
A soft eraser
A 300 mm long scale which includes scales of 1:100, 1:200, 1:5 and 1:50.
A 45° fixed set-square and a 30°/60° degree fixed set-square - longest side to
be about 230mm.
A plastic circle template.
FIXING THE DRAWING PAPER
Now fix a sheet of white A2 paper (Fig. 2.1)
A0
A1
A2
A3
A4
1180 x 840
840 x 590
590 x 420
420 x 295
295 x 210
Fig. 2.1 Different Sizes of Drawing Papers
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Construction Drawing Practices
USE THE TEE-SQUARE
You can use a tee-square to draw horizontal lines; press the stock of the teesquare against the left hand edge of the board and allow it to slide up and down
until the blade is in the required position. The pencil should be held against the
ruling edge of the tee-square blade (Fig. 2.2).
Head
A2
Working edge
Blade
Fig. 2.2 Check contact of T-square head with drawing board edge.
USING THE SET- SQUARE
You will need to use your set-squares for drawing vertical and sloping lines.
Move the straight edge/tee-square to the required position. Place the set-square
on the tee-square with its base on the top edge of the blade, and the vertical
edge in the required position (Fig. 2.3).
Fig. 2.3 Use Set-squares with T-square
All construction lines should be drawn first, followed by all final lines.
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Construction Drawing Practices
DRAWING THE BORDER AND TITLE PANEL
Now that the drawing paper is fixed to the board and you have some general
information about drawing lines, the first operation is to draw the border and
title panel.
The border should be drawn around the four edges of the paper 10mm wide.
Initially just draw the construction lines for the border.
Form the title block by drawing a construction line 40mm up from the bottom
border line. Add the short vertical and horizontal lines.
DRAWING RECTANGLES
Begin by drawing the construction lines for the 4 rectangles on the bottom left
hand corner of the sheet. For each rectangle first draw two horizontal lines about
30mm apart and about 75mm long. Join the ends of the horizontal lines by
drawing two vertical lines about 60 mm apart forming a rectangle 60x30 mm.
DRAWING CIRCLES & QUADRANTS
Draw the construction lines for the 3 circles & 3 quadrants in the top right hand
corner of the drawing. First draw the horizontal and vertical axes lines for each
circle. Then draw the circle. If you are using a compass to draw the circles, the
compass point should be carefully placed on the precise spot where the
horizontal and vertical axes cross. Then draw the circle as a curved construction
line. If you are using a circle template, you will need to relate the axes marks on
the template with the axes drawn on your drawing sheet.
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Construction Drawing Practices
DRAWING LINES TYPES
Lines vary in thickness and form according to their purpose and importance.
Construction lines have already been mentioned. They are setting-out or guide
lines, and they should be drawn as light as possible. They are generally covered
over by stronger final lines.
Thick active lines are continuous, and used to indicate important parts of
structures such as the outside and inside faces of walls; the faces of reinforced
concrete members and ground levels.
Thin active lines are continuous, and used to show items drawn as plan views (as
opposed to sectional plans) and as elevations; also to define less important items
shown in section.
Hidden lines are broken lines, and can be either thick or thin depending on their
important. They show work which is not visible - e.g. the position of beams on a
floor plan.
Centre lines are thin chain dotted lines and are used as the name implies, to
show the centre of things - e.g. the centre of a beam.
Break lines are thin continuous lines with a zig zag in them to show a break in the
continuity of the line or view.
Drain and other underground pipe lines may be shown by a thick chain line or a
thick continuous or broken line. In the case of underground drains, arrowheads
are often added to show the direction of flow.
Dimension lines and projectors may be shown in thin lines with arrows heads.
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Construction Drawing Practices
SECTION LINES OR PLANES
A section is a view of a building or object obtained by making an imaginary cut
through it. Sometimes called a section plane, it shows the position where the
imaginary cut is made. The line itself is a chain dotted line, with the line
terminated by arrows which point in the direction of the viewing.
TH IC K A C TIV E LIN ES
defining m ain outlines of stru ctures
in section
TH IN A C TIV E LIN ES
defining ou tlin es in p lan
and elevation
H ID D EN LIN ES-TH IC K O R TH IN
show in g w ork not visible or
w ork to be rem oved
C EN TR E LIN ES-TH IN LIN ES
B R EA K LIN ES-TH IN LIN ES
for b reak in continuity
SEC TIO N PLA N ES-TH IC K A N D TH IN
31
32
33
34
A
A
14
13
12
11
10
29
30
thick lines at end s and chan ges
of direction on ly th inelsew h ere
1 : 10
28
27
26
25
24
23
22
21
20
19
18
17
16
15
up
STA IR S
arrow ind icates d irection
of travel
RAM P
arrow indicates
d irection of fall
Fig. 2.4 Line Types
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Construction Drawing Practices
3
Drawing to Scale
It is not generally feasible to draw buildings, or parts of buildings, to their actual
size. Instead they are drawn in proportion to the actual measurement of the
object. This proportion is known as the scale of the drawing. Common scales are
1:1, 1:5, 1:10, 1:20, 1:50, 1:100, 1:200, 1:500, 1:1000, 1:1250, 1:2500, 1: 10000. If
the scale is 1:5, the object is drawn a fifth of its actual size; in other words the
object is five times larger than shown on the drawing. If the drawing is 1:10, the
object is drawn a tenth of its actual size, and so on.
USING A 1:50 & 1:100 SCALE
A 1:50 and 1:100 scale can be used for the floor plan of a building, both in
architectural and structural layouts.
USING A 1:200 SCALE
A 1:200 scale can be used for the floor plan of a large building, or the site plan of
a small building project.
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Construction Drawing Practices
4
Lettering and Dimensioning
One of the most important stages in producing a construction drawing is the
lettering and dimensioning of the drawing. Every drawing needs a title, and often
subtitles are required. In addition in order to make the drawing easier to
understand and more useful to the builder and others, descriptive notes and
dimensions will generally be required. Freehand lettering is the cheapest way of
annotating drawings and is generally the quickest method.
TYPES OF LETTER & GUIDE LINES
The two main groups of letters are ‘CAPITAL LETTERS’ and ‘lower-case letters’.
The use of lower-case letters is generally restricted to notes, but capital letters
can be used for both notes and titles. It is easier to produce legible capital letters
than lower-case letters, it is suggested that initially you use only capital letters on
your drawings. It is important that all letters be formed between guide lines. A
lower and upper guide line should be drawn as lightly as possible so that you can
just see them. Drawing them takes a little extra effort but is worth the trouble.
EXAMPLE OF LETTERS AND NUMBERALS
H
Top guideline
A BCDEF
GH I J K LM
N OP QR S T
U V WX Y Z
1 2 3 4 5
6 7 8 9 0
Middle guideline
Bottom guideline
0.7 H
Fig. 4.1 Sample of Lettering
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Construction Drawing Practices
DIMENSIONING
It is important that all drawings are fully dimensioned, so that the builder and
others know the required size of every part of the building. It is sensible however
not to duplicate dimensions, as this makes the drawing unnecessarily crowded.
Dimension lines should be unbroken lines. They can be terminated at their ends
by open arrowheads, solid arrowheads, oblique strokes, dots or circles.
Thin lines called projection lines, or projectors, should extend from about 2 mm
away from the part of the object being dimensioned to just beyond the
dimension line termination.
If any dimension is not drawn to scale, the letters “NTS” (not to scale) should be
written after the dimension.
HORIZONTAL DIMENSIONS
Horizontal dimensions should, where possible, be indicated on plans rather than
on elevations. Where feasible dimension lines should be located outside the
building or object rather than inside it.
D IM E N S IO N
L IN E S
200
O pen
A rro w h e a d
200
S o lid
A rro w h e a d
200
O b liq u e
S tro k e
200
70
65
65
70
135
200
D im e n s io n s
R u n n in g
D im e n s io n s
Fig. 4.2 Dimensioning methods
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Construction Drawing Practices
VERTICAL DIMENSIONS
Vertical dimensions should, where possible, be indicated on sections rather than
on elevations. All vertical dimensions of a building should relate to a site datum.
The site datum is a fixed vertical level on the site, and for convenience is often
set at the ground floor level of the building under construction.
DIMENSIONING BY LEVELS
Different members of the building team tend to follow different practices
regarding the measuring points for vertical dimensions. The client is concerned
with clear storey heights i.e. the dimension between the finished floor level and
the finished ceiling levels. Architects will invariably give the finished floor level
(FFL) on their drawings. Site staff work initially to the structural floor level (SFL).
Structural engineers need to know the structural floor level (SFL), and their
vertical dimensions will generally be measured from SFL to SFL.
ORIENTATION OF PLANS
North points are generally shown on key plans, site plans, block plans and
sometimes floor plans, to indicate the position of north relative to the site or
building. The point of the arrow should be drawn to face north.
DATUM , LEVEL SYM BOLS
N
N orth point
SSL
Level on plans
FFL
Level on plans
FFL
123
Ceiling height on plans
Level on sections
and elevations
Fig. 4.3 North Points and Level Marks
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Construction Drawing Practices
5
Graphic Conventions
Construction drawings are a means of communication between the various
members of the building team, and it is important that they employ a common
graphical language. It helps to achieve this if agreed standards are followed in
respect of lines, hatching and symbols, etc.
REPRESENTATION OF MATERIALS
In sectional views of a building, the parts of the structure which are cut by
section plane may be hatched to indicate the nature of the materials used.
Common examples of hatching for construction materials.
MATERIAL SYMBOLS IN SECTION
Brickwork
Blockwork
Concrete
Plaster/Render
Timber-planed
Subsoil
Topsoil
Granular fill
Damp-Proof Membrane
Metal
Fig. 5.1 Graphical Symbols of Building Materials
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Construction Drawing Practices
DOORS
There are standard ways of indicating on plans the opening methods for doorsi.e. whether they are swing doors or sliding doors-and the direction in which they
open.
DO O R SY M BO LS
S i n g le le a v e s
o p en in g 9 0
S i n g le le a v e s
o p e n in g 1 8 0
T w o le a v e s e a c h
o p e n in g 9 0
S tr a ig h t s lid i n g
Fig. 5.2 Door Symbols
WINDOWS
The opening methods for windows are generally indicated on the elevations.
WINDOW SYMBOLS IN HORIZONTAL SECTION
Any type
With frame
WINDOW SYMBOLS IN ELEVATION
Hinged at side
Hinged at top
F
Sliding horizontally
Fixed
Fig. 5.3 Window Symbols
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Construction Drawing Practices
SYMBOLS
There are wide range of standard graphic symbols available to indicate the
position of various components, and related information. Some common
examples are given below, but reference needs to be made to BS 1192 for full
details of the recommendations for symbols and other graphic conventions.
ARCHITECTURAL DRAWING SYMBOLS
Electrical
distribution
board
Direction of span
w.c close-coupled
Seat
BUILDING SERVICES DRAWING SYMBOLS
One-way
switch
Two-way
switch
Socket outlet
Switched
socket outlet
Circuit
on plan
Pipe valve
Non-reture
pipe valve
Meter
Bath
Sink
References:
BS 1192 Part 1 and 3: 1987
Fig. 5.4 Architectural and Building Services Symbols
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6
Orthographic Projection
Buildings, and the materials and components of which buildings are constructed,
are three dimensional. That is to say they have length, width and height. It is
possible to draw a picture of a building or object to show these three
dimensions. Generally however in construction drawing the method used to
describe buildings or objects pictorially is called orthographic projection. This
method uses views termed plans, elevations and sections, which have only two
dimensions.
FIRST AND THIRD ANGLE PROJECTION
Since there are two systems of orthographic projection, it is necessary to give
them names for identification. They are commonly known as first angle
projection and third angle projection.
To explain why they are so called, you may place the two boxes together as
shown. It can be seen that one system falls neatly in the first quadrant and the
other in the third quadrant (Fig. 6.1).
TOP (PLAN) VIEW
VERTICAL PLANE
END VIEW
HORIZONTAL PLANE
W
VIE
ION
AT
V
LE
TE
RN
FO
FRONT ELEVATION
END VIEW
PLAN
FRONT ELEVATION
PLAN
FIRST ANGLE PROJECTION
END VIEW
THIRD ANGLE PROJECTION
Orthogonal projection of an object
Fig.6.1 1st and 3rd angle Projection
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Construction Drawing Practices
PROJECTION SYMBOLS
In order to indicate the angle of projection to be used, the symbols has to be
printed on the drawing (Fig.6.2). Examples of Orthographic Projection are shown
in Fig 6.3.
Projection
d
Symbol
d
1.25d
30
First angle
Third angle
Projection symbol proportions
Fig. 6.2 Projection Symbols
Plan
Side elevation
Front elevation
Fig. 6.3 Example of 3rd Angle Projection
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Construction Drawing Practices
SECTIONAL VIEWS
Objects with little interior detail can be represented satisfactorily in orthographic
projection by exterior views, the interior construction being shown by hidden
detail lines : When the interior detail is more complicated, then the hidden detail
lines may be confusing and difficult to interpret correctly. In such cases the
draughtsman imagines the object to be cut by a plane, and assumes the part of
the object between his eye and the plane to be removed. This exposes the
interior detail which can then be shown by full lines instead of hidden detail lines.
The position of the cutting plane is selected by the draughtsman to show the
interior of the object to the best advantage. For an object which has internal
details that are not on one line, a staggered section may be appropriate. When a
revolved section of an object is required, it may be drawn directly on the part
under consideration.
Front elevation
Section side elevation
Section plan
Fig. 6.4 Sectional Elevation and Plan
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Construction Drawing Practices
The example below shows the offset cutting plane of the staircase, this practice
should be continued to the top landing; each step should be drawn but once.
The top landing will look much as it would with a normal cutting plane. The view
down the stairwell would show the down flight as it would normally appear in
the stairwell. The limit line shows where the stairs break between floor plans in
the same location on the plans of each floor. Double limit lines are used to
separate the up half from the down half where they meet in plan.
4
FOURTH FLOOR
4
3
3
2
2ND & 3RD FLOOR
2
1
1
FIRST FLOOR
Fig. 6.5 Section of Staircase
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Construction Drawing Practices
7
Pictorial Views (3D)
7.1
Isometric Projection
Isometric projection is a method of showing three faces of an object on one
drawing (Fig. 7.1). The word isometric means ‘equal measure’ and the basis of
isometric projection is that three lines defining the three faces or planes produce
three equal angles of 120 degrees and the sides are shortened to 82% of their
true length (Fig. 7.2). which shows, in isometric view, a solid concrete building
block and a hollow concrete building block. Isometric projection is achieved in
practice by drawing all vertical lines as vertical, and all horizontal lines at 30
degrees to the horizontal, sloping either to the right or left.
10 0
60
20
20
120
20
44 0
20
120
20
215
1 20
20
o
120
o
120
o
120
30°
30°
SOLID CONCRETE
BUILDING BLOCK
HOLLOW CONCRETE
BUILDING BLOCK
Fig. 7.1 Examples of Isometric Projection
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Construction Drawing Practices
50
82% OF THE
ORIGINAL SIZE
40
Natural scale
x
30
x
x
20
x
10
x
x
30
20
40
45
50
Isometric scale
30
10
x
ISOMETRIC PROJECTION
ISOMETRIC DRAWING
CONSTRUCTION OF ISOMETRIC SCALE
C
C
C
R
R
R
R
C
STAGE 1
STAGE 2
STAGE 3
FOUR CENTERS MOTHOD
Fig. 7.2 Comparison of Isometric Projection and Isometric Drawing & Construction of
Isometric Circle
It is normal practice to make the measurements on isometric drawings to the
same scale as used for plans, elevations and sections. This is not mathematically
correct however, and slightly distorts the appearance of the plan view. It is
possible to produce an accurate isometric drawing by using a special scale, but
consideration of this aspect is inappropriate to an introductory book on
construction drawing.
An isometric projection is found by constructing a view that shows the diagonal
of a cube as a point. An isometric drawing is not a true projection since the
dimensions are drawn true size rather than reduced in size as in projection. By
using the isometric drawing instead of the isometric projection, pictorials can be
measured using standard scales, the only difference being the 18% increase in
size (Fig. 7.2).
The four-center ellipse method can be used to construct an approximate ellipse
in isometric by using four arcs that are drawn with a compass. The four-centre
ellipse is drawn by blocking in the orthographic view of the circle with a square
that is tangent to the circle at four points. This square is drawn in isometric as a
rhombus. The four centres are found by constructing perpendiculars to the sides
of the rhombus at the midpoints of the sides (step 1 to 3).
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7.2
Perspective Projection
A perspective is a view that is normally seen by the eye or camera, and is the
most realistic form of pictorial. All parallel lines converge at infinite vanishing
points as they receded from the observe. There are three basis types of
perspectives are: one-point, two-point, three-point, depending on the number of
vanishing points used in their construction (see Fig. 7.3).
One-point perspective: The one-point perspective has one surface of the object
that is parallel to the picture plane: therefore it is true shape. The other sides
vanish to a single point on the horizon called a vanishing point.
Two-point perspective: A two-point perspective is a pictorial that is positioned
with two sides at an angle to the picture plane; this requires two vanishing
points. All horizontal lines converge at the vanishing points, but vertical lines
remain vertical and have no vanishing point.
Three-point perspective: The three-point perspective utilizes three vanishing
points since the object is positioned so that all sides of it are at an angle with the
picture plane. The three-point perspective is used in drawing larger objects such
as buildings.
VP
Hor
ONE POINT
VP
Hor
VP
VP
Hor
TWO POINTS
VP
THREE POINTS
Fig. 7.3 Aerial Views and Vanishing Points
Abbreviation:
PP= Picture Plane is the plane on which the perspective is projected. It
appears as an edge in the top view.
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SP= Station Point is the location of the observer’s eye in the plan view.
The front view of the station point will always lie on the horizon.
CV= Center of Vision is a point that lies on the picture plane in the top
view and on the horizon in the front view. In both cases, it is on the line
from the station point that is perpendicular to the picture plane.
VP= Vanishing Point is all vanish line (VL) Converge at infinite vanishing
points as they recede from the observer.
Hor.= Horizon or Eye level is a horizontal line in the front view that
represents an infinite horizontal, such as the surface of the ocean.
GL= Ground Level is an infinite horizontal line in the front view that
passes through the base of the object being drawn.
Different views can be obtained by changing the relationship between the
horizontal and the ground line (Fig. 7.4). An aerial view will be obtained when the
horizon is placed above the object in the front view. When the ground line and
the horizon coincide in the front view, a ground-level view will be obtained. This
would give the view that would be seen if your eye was looking from the ground.
A general view is one where the horizon is placed above the ground line and
through the object, usually at a height equal to the height of a person.
VP
VP
VP
VP
GL
GL
GROUND -LEVEL VIEW
GENERAL VIEW
Fig. 7.4 Ground Level View and General View
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7.3
Oblique Projection
SI
ZE
Oblique pictorials are three-dimensional pictorials made on a plane of paper by
projecting from the object with parallel projectors that are oblique to the picture
plane. There are three basis types of oblique drawings are used that are based
on these principles: The three types are: (1) cavalier, (2) cabinet, (3) general (Fig.
7.5). In each case, the angle of the receding axis can be at any angle between 0°
and 90°. Measurements along the receding axes of the cavalier oblique are true
length (full scale). The cabinet oblique has measurements along the receding
axes reduced to half length. The general oblique has measurements along the
receding axes reduced to between half and full length. An oblique should be
drawn by constructing a box using the overall dimensions of height, width, and
depth with light construction lines.
FU
LL
FULL SCALE
L
HA
CA
LE
VARIES 0--90
0
0
0
0
0
30
FS
30
0
VARIES 0--90
TRUE SIZE
CABINET PROJECTION
CAVALIER PROJECTION
HA
LF
TO
L
FU
LS
CA
LE
0
30
0
0
VARIES 0--90
TRUE SIZE
GENERAL OBLIQUE
Fig. 7.5 Oblique Projection
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8
Construction Drawings
8.1
Site Plans
A site plan is a location drawing, and like most plans is a view looking
downwards. It supplies a bird’s eye view of the shape, size and layout of the
entire site.
The purpose of a site plan is to
•
provide a general picture of the site, including its shape and extent;
•
locate the buildings and other elements of the project - e.g. roads, garden
walls and landscaping- both horizontally and vertically ;
•
indicate the levels and surface features of the finished site;
•
sometimes provide information on external services, especially
underground drainage.
GRIDS
The use of grids to which sizes and locations of building components may be
related, is helpful in preparation of all types of drawings and particularly so when
modular coordination is applied to design and construction. Grid rotations
should be used as appropriate for each form of grid. Most common grid rotation
is using letters to define the lines on axis and numerals to define the lines on the
other axis.
8.2
Floor Plans
Floor plans are generally the most useful, and the most used of the location
drawings. They are really sectional plans because they show the view obtained by
cutting horizontally through a building at some point above the floor level. It is
assumed that you move away the top part of the building and look down at the
plan of the remaining bottom part. This plan view will not only illustrate the
arrangement of the rooms and spaces and their shapes, but will also show the
thickness of all the external and internal walls.
The level at which you cut horizontally through a building is commonly assumed
to be 1metre above the floor level. This has the advantage of passing through
most of the windows and doors, which means that dimensions giving the
positions of all openings can be given. An example of a floor plan is shown on
Fig. 8.1.
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N
6600
800
2100
1450
900
W4
A
1350
W3
800
D2
4100
1100
S.F.L.
+5.650
W2
900
KITCHEN
W1
900
1200
16 Risers
up
D5
1350
DINING
All ext. walls
200 thick
1900
BATHROOM
A
A
D4
9100
2100
950
4100
1300
900
9100
750
LIVING
W5
D1
100
D3
900
D6
4100
W9
BEDROOM 1
3100
BEDROOM 2
900
All int. walls
100 thick
3800
1650
2300
B
W7
W6
1350
900
600
900
W8
600
900
1350
6600
1
ELEVN
2
Fig. 8.1 Floor Plan - General Layout
The purpose of a location floor plan is to:
• indicate the shape and the layout of the building;
• provide the setting out dimensions for the building;
• locate spaces such as rooms, and parts such as doors;
• provide references stating where more detailed information can be found.
WALLS AND PARTITIONS
•
Thick lines should be used to define the inside and outside faces of external
walls, and both faces of the internal partitions.
•
Where cavity walls form part of the construction the cavity may be indicated
by thin lines, but it is suggested you omit this detail on the 1:50 floor plan.
•
Hatching is often used, particularly on larger scale plans. Where floor plans
show existing walls, they are often filled in solid.
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WINDOWS
•
Windows will be positioned laterally on the floor plans. Their positions within
the wall thickness will be shown on the assembly drawings if these are
provided. However, where the scale of the floor plan is 1:50 or larger, it is
sensible to locate the windows in approximately their correct positions
relative to the wall faces.
•
It is usual practice to number each window - W1, W2, W3 etc.
DOORS
•
Doors should also be numbered - D1, D2, D3 etc.
•
At each door position it should be made clear which way the door is hung.
OTHER ITEMS
•
Sanitary fittings, cupboards and other fittings should be shown in outline on
floor plans. It is important however not to repeat information which is given
on other drawing, such as assembly and component drawings. If too much
information is provided, the drawing will become confusing and difficult to
read.
ROOM NAMES AND NOTES
•
A name should be given to each room or space. On large projects room
numbers will also be provided.
•
Notes should be kept to a minimum and duplication of information provided
on other drawings should be avoided.
•
The most important thing is that the lettering should be easy to read.
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8.3
Sections
A section is a view of a building or object obtained by making an imaginary cut
through it. The term section is mainly used where the cut is made in a vertical
direction, and this is so in the case of location sections.
A vertical section through a building will show details of the construction of the
foundations, walls, floors, roof and other parts. The number of sections required
of a building will depend on its size and complexity. Generally there will be at
least two sections - one of these will be a cross section, across the width of the
building. The other will be a longitudinal section, along the length of the
building. Sections are intended to help the builder construct the building, so the
exact position of the section should be chosen to show as much construction as
possible.
The purpose of a location section is to (a) give a vertical view of the building; and
(b) provide overall vertical dimensions and levels.
WALLS AND PARTITIONS
•
Thick lines should be used to define the inside and outside faces of external
walls, and both faces of the internal partitions.
•
Where cavity walls form part of the construction the cavity is often indicated
by thin lines.
•
Hatching is often used, particularly on the larger scale sections.
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OTHER STRUCTURAL ELEMENTS
•
Thick lines should be used to define both faces of concrete floor and roof
slabs.
•
Thick lines should also be used to define the faces of other structural
elements, such as foundations and beams, when these are viewed in section.
U.Roof
ROOFING
(detail ref. to
other dwg.)
1200
100-110
2835
200
45 FALL
125
R/F
125
250
2675
15 THICK 1:3 C/S
LIME PLASTER
25 THICK 1:3
C/S SCREED
1/F
Earth
S.F.L.
+5.650
G/F
1000
BLINDING
1000
50
400
750
D.P.C. ON 150
THICK HARDCORE
150
150
1050
2675
1250
100
Fig. 8.2 Section A-A of House in Fig. 8.1
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8.4
Elevations
An elevation is a view you get if you look in a horizontal direction at the vertical
side, or face, of a building or object. When drawing an elevation you need to
take the horizontal dimensions from the plans and the vertical dimensions from
the sections. An example of a elevation is shown in Fig. 8.3.
The purpose of a location elevation is to (a) show the external faces of the
building; and (b) locate the door and window openings and other features of the
building.
Dia. 25 PVC
Drain Pipe
1445
2835
U.Roof
2675
75-80
R/F
50x230 CERAMIC
WALL TILE
1/F
S.F.L.
+5.650
150
25-30
2675
100
G/F
Elevation of House
Fig. 8.3 Elevation of House in Fig. 8.1
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8.5
Assembly Drawings
Assembly drawings provide precise, detailed information as to the construction
of buildings, including matters such as the fixing of materials, components and
elements. The usually consist of sectional plans and vertical sections, but it will
be appropriate on occasions to use other methods, including isometric
projection and elevations.
On some smaller projects it may not be necessary to produce assembly drawings,
as the assembly information can be given on the location drawings, particularly
when they are drawn to a scale of 1:50.
The purpose of an assembly drawing is to:
•
•
•
show the construction of individual elements of structure such as
foundations, walls, floors and roofs
show the arrangement where two elements meet each other - e.g. the
junction between a wall and a roof, and between a column and a wall
provide a reference as to where more detailed information about a
particular part of the construction is provided.
EXAMPLES OF ASSEMBLY DRAWINGS
Assembly drawings provide information to contractors which enable them to
construct buildings on site. They include the assembly of both structural and non
structural elements, components and materials. An example is given below.
200
min.150
125
2 0 x 2 0 re c e s s
3 8 th .c o n c .r o o f tile
FA LL
2 5 th .1 :3 c /s s c re e d
w / g .i.m e s h r e in f.
5 0 th .th e rm a l
in s u la tio n b o a rd
2 5 x 2 5 1 :3 c /s
c o r n e r fille t
125
2 0 th .a s p h a lt c o a t
a s p h a lt m a t
m in .2 5 th .1 :3 c /s s c r e e d
la id in fa lls
100
d ia .2 5 g r o o v e
R o o fin g D e ta i l
Fig. 8.4 Details at Roof Edge
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8.6
Component Drawings
A component drawing provides detailed information about the nature and
manufacture of a specific item incorporated in a building. This is in contrast to an
assembly drawing which shows several parts, or a location drawing which
provides general information. Components include things such as skirting and
lintels, as well as larger items manufactured off-site, such as windows and kitchen
cupboards.
The purpose of a component drawing is to (a) show the nature, shape, assembly
method and further details of components, required by the manufacturer and
others; and (b) provide additional information which cannot be conveniently
given on location or assembly drawings.
83dp.stile & rail
45dp.timber core
4x45dp.lock
blocking
3th.plywood facing
to both sides
12th.teak lipping
to all edges
DOOR D1,D2&D5
Fig. 8.5 Component Drawings of Wooden Doors
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8.7
Structure Engineering Drawing
Structural engineering drawings help those, whose job it is to fabricate, erect,
supervise and integrate the structural engineering work. The different needs and
priorities of these people influence the method of providing, the information,
which will sometimes vary from architectural drawing techniques previously
discussed. Some of the implications are mentioned below.
TYPES OF STRUCTURAL ENGINEERING WORK
Structural engineers and structural engineering technicians produce drawings for
a wide range of structural methods, including structural steelworks, reinforced
concrete using in situ, precast and prestressed concrete, structural brickwork and
blockwork, and structural timber work.
STRUCTURAL DETAILING
The process of preparing working drawings for structural engineering work is
generally referred to as structural detailing. The general principle followed is to
break down the total structure into individual elements such as columns, beams,
floor slabs etc., and then to detail each element in turn.
STRUCTURAL STEELWORKS
The three main groups of drawings for illustrating steelwork structures are
general arrangement drawings, fixing details, and details of individual members.
General arrangement drawings include steel framing plans, elevations and
sections. Fig. 8.6 is an example of a steelworks floor framing plan. Steel framing
plans indicate the positions and sizes of beams at a specific floor or roof level,
together with the positions and sizes of columns. Elevations and sections will
show columns and beams as well as additional members such as wind bracing.
MARK REFERENCES FOR BEAMS AND COLUMNS
It is necessary to identify each steel member by a distinctive mark reference
whenever it appears on a drawing. The same mark must also be painted on the
actual member before it leaves the workshop for dispatch to the site.
A common system is to mark the horizontal grid lines on the steel framing plans
with numbers-1, 2, 3 etc. -and the vertical grid lines with letters- A, B, C etc.
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This system enables each member to be identified. Columns are given a mark
related to the grid intersections on the plans. Thus the top left hand column is
given the mark of A1 because it is located where grid lines A and 1 intersect. The
marks for the beams are a combination of the floor reference and the grid line
letter and number. For example in Fig. 8.6 the horizontal beam in the top left
hand corner is marked as C-1A. The letter C indicates it is a second floor beam;
the figure 1 denotes that the beam is located at grid line 1; and the letter A
denotes that it begins at grid line A.
1
2
3
4000
4
4000
4000
457x152x67kg UB
457x152x67kg UB
457x152x67kg UB
(C-A1)
(C-A2)
(C-A3)
Ditto
Ditto
Ditto
(C-B1)
(C-B2)
(C-B3)
(C-4A)
Ditto
(C-3A)
Ditto
(C-2A)
Ditto
(C-1A)
406x178x67kg UB
5000
A
Ditto
Ditto
Ditto
(C-C1)
(C-C2)
(C-C3)
(C-4B)
Ditto
(C-3B)
Ditto
(C-2B)
Ditto
(C-1B)
406x178x67kg UB
5000
B
(C-D1)
(C-D2)
(C-D3)
(C-4C)
Ditto
(C-4D)
Ditto
Ditto
Ditto
Ditto
(C-3C)
Ditto
(C-2C)
Ditto
(C-1C)
406x178x67kg UB
5000
C
Ditto
Ditto
(C-E1)
(C-E2)
(C-3D)
Ditto
(C-2D)
Ditto
(C-1D)
406x178x67kg UB
5000
D
Ditto
E
Notes:
(C-E3)
All columns are 254x254x73kg UC
Fig. 8.6 General Layout of Structural Steel Framed Building
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FIXING DETAILS
Fixing details provide information on the fixing of members to each other, or to
different parts of the structure. Examples are the fixing of a column to a
foundation, a connection between a beam and a column, the connection of one
beam to another beam, and the splicing of similar members to each other. Fig.
8.7 is an example of a fixing detail showing the connection between a steel
column and a concrete base.
3 0 5 x 3 0 5 U n iv e rs a l c o lu m n
150mm concrete
encasting shown
by broken line
fillet weld
s te e l le v e llin g w e d g e s
grout
removable bolt
bores of plastic
form, p.v.c. tube,
etc.
R .C . fo u n d a tio n
h o ld in g d o w n b o lts g ro u te d
afte r fin a l le v e llin g
1 0 0 x 1 0 0 p la te w a s h e rs
R e in fo rce m e n t b a r
Fig. 8.7 Details of Steel Column and Holding Down Bolts
The various steel members -universal beams, universal columns, rolled joists,
rolled channels, tees and angles- are fixed together by welding or bolting, either
in the workshop (shop connections) or on the construction site (site
connections). Fig. 8.8 is an example of details of connections.
2/100X75X10
grade 50
2/100X75X10
grade 50
Use M20 bolt
grade 4.6
Truss shoe
Eaves beam
229X76 grade 43
Roof leg 305X127X37 UB
grade 43
Enlarged detail at eaves of structural steel work
Fig. 8.8 Connection Details of Steel Members
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REINFORCED CONCRETE STRUCTURES
The two main groups of drawings for illustrating reinforced concrete structures
are general arrangement drawings, reinforcement drawings. General
arrangement drawings are floor plans, roof plans, sections and elevations, drawn
to a small scale and providing an overall view of the work. They supply the
setting out dimensions, the positions and sometimes the sizes of all the
members. Fig. 8.9 is an example of a small plan of a typical floor showing slab
thickness and reinforcement, beam serial numbers and sizes. A reference grid is
provided similar to that previously described for a structural steel building.
Reinforcement drawings of structural elements are drawn to a larger scale and
give detailed information about the reinforcement (Fig. 8.10). There is no excuse
for ambiguity, and it is essential that all drawings are easy to read, and cannot be
misunderstood.
N
A
B
C
1/A-B
1/B-C
50x300
450x300
1
4000
C/1-2
450x300
2/B-C
450x300
C/2-3
2/A-B
450x300
450x300
B/1-2
150
450x300
A/1-2
450x300
150
3/B-C
450x300
450x300
4000
3500
1500
3/A-B
150
A/2-3
450x300
2
3
Slab and beam details on a small-scale floor plan
A
B
21T10-7-200T2
C
21T10-8-200T2
21T10-7-200T2
1
21T10-10-200T1
18T10-11-200T1
A
21T10-1-200B1
21T10-1-200B1
A
21T10-3-200B2
18T10-4-200B2
21T10-12-200T1
18T10-13-200T1
2
21T10-5-200B2
18T10-6-200B2
3
8T10-9-200T2
7
10
8T10-9-200T2
8T10-2-200B2
8
7 11
3
1
1
4
Fig 8.9 R.C. Details of Floor Slab
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1
2
2T20-4
2T10-5
4T20-6
Links 18T10-10-200
2T10-7
Links 16T10-10-200
4T20-1
3T20-3
4T20-2
4000
3500
1
3
2
150
9
7
6
450
6
450
5
9
7
450
150
Beam 3/B-C
150
Beam 3/A-B
5
2T20-8
3
10
1 1 11
2 2 22
33 3
Section 1-1
Section 2-2
Section 3-3
Fig. 8.10 R.C. Details of Beam
REINFORCEMENT IDENTIFICATION
Standard abbreviations are used to provide information about the reinforcement.
•
R-mild steel round bars
•
T-high tensile bars
•
T1/B1-reinforcement near the top and bottom face of the concrete
respectively.
Each reinforcing bar on a drawing is given a notation consisting of standard
abbreviations, dimensions in mm and mark numbers. This information is
provided in the following sequence: number, type, size, mark, centres and
location.
The meaning of the notations given to the reinforcement (Fig. 8.9 and Fig. 8.10).
•
21T10-10-200T1, this means that there are 21 bars, which are of high tensile
steel, with a diameter of 10 mm, and an bar mark of 10. The bars are spaced
200 mm apart and placed near the top face of the concrete.
•
Links 18T10-9-200, this means that there are 18 stirrups, which are high yield
bars, of diameter 10 mm and bar marked as 9.
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8.8
Service Drawings
TYPES OF BUILDING SERVICE WORK
Building services are generally assumed to include hot and cold water supplies,
above and below ground drainage, including sanitary appliances, refuse disposal,
heating, ventilation, air conditioning, electrical installations including lighting,
telecommunications, gas installations, fire protection, mechanical conveyors and
security systems. Drawings are required for all of these services.
In this introduction to construction drawing a few simple examples are given of
below ground drainage, water supplies and electrical installations for domestic
buildings.
MAIN GROUPS OF DRAWINGS
The three main groups of drawings for illustrating services work are general
layouts locating the arrangement of pipes, cables and ducts; details of plant
areas; and details of specific items. In addition there are schedules for items such
as manholes, radiators, valves etc., but these are beyond the scope of this
reading material.
USE OF GRIDS
In projects where a structural grid is used, the services elements should be
related to this grid. In other cases the plant and equipment will be shown on
services drawings in relation to a modular grid.
IDENTIFICATION OF SERVICE COMPONENTS AND EQUIPMENT
Services drawings provide information about a wide variety of different
components and equipment. In order to identify individual items, it is usual to
give them a reference number on drawings such as services layout drawings and
location plans. An example is that a radiator might be given a reference of R305,
which would mean it was a radiator, on the third floor, and was the fifth
consecutive radiator on that floor.
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Construction Drawing Practices
GENERAL LAYOUTS
Copy negatives (transparent copies) of the architect's 1:100 location drawings are
often used by the building services engineers and technicians to show the
general layout of the pipe work, ductwork, trunking, cables etc. It is advisable to
obtain these copy negatives from the architect at an early stage before too much
detail is added. However, where this procedure is adopted, it is important that
later revisions to the architect's drawings are taken into account on the copy
negative. A simple example of a general layout is shown on Fig. 8.11 which is a
wiring layout for lighting in a bungalow.
PLANT AREA DRAWINGS
Areas where the services equipment is concentrated are normally drawn to a
larger scale, such as 1: 50 and 1: 20. Plans of these plant areas are the
commonest form of plant area drawings, but elevations and sections are often
required. Typical areas to be covered are boiler rooms, air handling plant rooms
and electrical substations.
DETAILS OF SPECIFIC SERVICES ITEMS
As the scales of general layouts and plant room area drawings are comparatively
small, additional detailed information on individual items is also required. This
additional information is given on details of specific services items.
MAIN SWITCH (MCB, RCD)
KITCHEN
DINNING
BATHROOM
LIVING
BEDROOM 2
BEDROOM 1
Fig. 8.11 Building Services Drawing - Electrical Wiring Layout
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Construction Drawing Practices
8.9
Freehand Drawings
Freehand or sketch drawings are used for a variety of purposes. They may record
or explain the appearance and construction of an existing building, or sketch in
outline a designer's ideas for a proposed structure. Often freehand drawings will
be used as preliminary constructional details, or to clarify on-site details which
have not been made clear by the production drawings issued to the contractor.
Freehand drawings may also be used as presentation drawings. This type will
need to be of a high standard and will often incorporate advanced drawing
techniques, including perspective drawing, shadow projection and rendering.
DRAWING TECHNIQUES
In order to produce satisfactory freehand sketches of existing structures the
draughtsperson will need to gain experience in the art of observation-sometimes
referred to as training the eye. They will also need to acquire the ability to draw
straight and curved lines of an even quality. Thirdly they will need to gain the
ability to draw in proportion.
PRODUCTION INFORMATION SKETCH DRAWINGS
Sometimes architects and other design team members will need to produce
immediate information. The information must be precise and accurate, but can
conveniently be provided in the form of freehand sketch drawings.
Some general advice on the matter of freehand sketches is given below.
1.
Draw everything first as fight construction lines, and only firm in the lines
when you are satisfied that everything is drawn accurately and in
proportion.
2.
Where feasible, divide what you are drawing into a number of simple
geometrical shapes.
3.
If what you are drawing is symmetrical, draw in the axes.
4.
Draw in the main geometrical shapes first. Then add the detail.
5.
Draw horizontal lines from left to right, unless you are left handed, in which
case you will probably find it easier to draw them from right to left. If the
line to be drawn is a long one, you can draw it as a continuous line made
up of a series of shorter fines about 50 mm long.
6.
Draw vertical lines from top to bottom.
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Construction Drawing Practices
7.
Ensure that lines which are at right angles to each other are drawn as exact
right angles.
8.
In the case of circles first draw the axes, and mark the points on the axes
where the circle is meant to cross.
9.300
13000
9.500
5500
7000
2000
9.700
9.700
PROPOSED
HEDGE
HOUSE
9000
EXISTING
F.F.L. 10.000
9.850
9.850
8000
COSSLES
PROPSED TREE
10.400
10.300
3500
1500
5000
1000
Fig. 8.12 Freehand Sketch of a Site Plan
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References :
1.
B.S. 1192 : Part 1,2,3,4,5 Construction Drawing Practice
2.
Construction Unit (1998), Computer-Aided Design using MicroStation 95,
Industrial Centre, The Hong Kong Polytechnic University
3.
Dennis Neeley (1996), CAD and the Practice of Architecture, New York, N.Y.:
J. Wiley
4.
Earle James H., (1991), Drafting Technology, Addison-Wesley
5.
Elsheikh Ahmed (1995), An Introduction to Drawing for Civil Engineers,
McGraw-Hill
6.
Jude D.V., (1983), Civil Engineering Drawing London ; New York : Granada
7.
Muller Edward J (1996). Reading Architectural Working Drawing , Prentice
Hall
8.
Pickup F. & Parker M. A. (1970) Engineering Drawing with Worked Example
London : Hutchinson,
9.
Ratensky A. (1983), Drawing and Model making, Whitney Library of Design
10.
Thompson Arthur, (1993). An Introduction to Construction Drawing, London
: E. Arnold,
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