• It is impractical to draw buildings, plots of land, and large parts of buildings such
as doors and windows to their full size.
• They simply would not fit on a piece drawing paper. Instead they are normally
drawn to a smaller reduced size. The size they are reduced will be to a ratio of the
• Twice as small 2:1
• Ten times smaller 10:1 etc
• When drawings are drawn in this way they are called SCALED DRAWINGS
• To draw buildings and objects to a scale, recognised ratios called SCALES are
used to relate real dimensions and measurements to a drawing.
Building reduced in size to fit on drawing paper
The main scales 1:1 Full size used for unusual details or templates
or ratios used in 1:2
construction 1:5 Complicated building details
drawings are-: 1:10
Plans, elevations and sections
1:500 Site plans
Block or location plans
Use of scales
• The choice of scale will depend on two things:
1. The size of the object to be drawn
2. The amount of detail that needs to be shown
• A scale is used to measure distances on drawings and for taking
measurements of a drawing.
• The distance shown above represents 15.35m it will be to a scale.
• If scaled dimensions and written dimensions disagree, then the
written dimension should always be used.
• The scale shows how much smaller the plan or object is to its original
Use of scales
• In a house drawing to a scale of 1:20 :
• 1 mm will represent 20 mm
• 2 mm will represent 40 mm
• 10 mm will represent 200 mm
• 100 mm will represent 2000 mm or 2 m
• To a scale of 1: 10 100 mm will represent 1,000 mm or 1 m
• To a scale of 1: 100 100 mm will represent 10,000 mm or 10 m
• To a scale of 1: 50 100 mm will represent 5,000 mm or 5 m
• To a scale of 1:5 250 mm will represent 1,250 mm or 1.250 m
• To a scale of 1:200 150 mm will represent 30,000 mm or 30 m
• It is simply a matter of multiplying the scale measurement by the scale ratio
• 1: (10) x 100mm = 1000mm or 1m
• 1: (50) x 100mm = 5000mm or 5m
• 1: (200) x 150mm = 30,000mm or 30m
• The drawing shows a ground
floor plan of a small bungalow
drawn to a scale of 1:100.
• Using a scale rule complete
the table by inserting all the
• Complete the tables below by taking measurements from ground
floor plan of bungalow
Room Length Width Area
• Insert the width of all the windows of the bungalow
Scale Rule – Scale 1:100
• Mark on the scale rule the line representing 1.6m to a
scale of 1:100
Scale Rule – Scale 1:20
• Mark on the scale rule the line representing 1.7m to a
scale of 1:20
Scale Rule – Scale 1:50
• Mark on the scale rule the line representing 6m to a
scale of 1:50
Scale Rule – Scale 1:1250
• Mark on the scale rule the line representing 130m to a
scale of 1:1250
Lines should be of THREE thicknesses
0.75 – 1mm thick for borders and
0.35 – 0.5mm thick ½ the thickness of
the thick lines for hatching
0.2 – 0.25 mm thick ½ the thickness of
the medium lines for dimension lines.
• All drawings must be clear and accurate and easily
understood by everyone who uses them.
• In order to achieve this method of layout, symbols and
abbreviations have been standardised ( See BS 1192 ).
• Next slide are some examples of the most common
different lines and what they represent on working
• Thick Main outlines
• Medium General details and outlines
• Thin Construction and dimension Lines
• Breakline Breaks in the continuity of a drawing
• Thick chain Pipe lines, drains and services
• Thin chain Centre lines
• Section line Showing the position of a section cut,
the pointers show the direction of the view
• Broken line Shows hidden details
• Dimension line Indicates the distance between two points
On site plans this sign shows the
direction of true North.
1 2 3 4 5 6 7 8 9 Stairs
Arrow shows the direction of
the steps and the number of
steps in the stair.
A dotted line in the shape of a pointed arrow indicates the
haging edge of a window sash
• These should be thin lines, the ends can be shown in several ways
• Open arrow head showing outside measurement 0.5m
• Closed arrow head showing inside measurement
1000 2500 50 3500
• Written dimension on horizontal lines should always be
on top, preferably in the centre.
• Written dimensions on vertical lines should be to the left
and preferably in the centre.
• All dimensions should be read from the bottom right
• Symbols are graphical illustrations, which are used to represent
the different building materials and components in a building
• It was the custom to colour drawings, particularly the drawings
submitted to the local authority for planning permission.
• Sadly the practice is rarely used as it is slow and time consuming.
• However is still the custom to colour in the position of a building in a
block plan to show the position of the building and its surrounding
• Next slide are some of the most common symbols used and what
• The majority of drawings will require lettering and numbering.
• This may vary from very little or none on a design to a great deal of production
drawings and schedules.
• Various techniques can be used, their application depending upon the type of
drawing and its use.
• The quickest method is by hand and it is important to develop a neat and
accurate style from the beginning.
• Poor lettering can ruin an otherwise good drawing.
• Any lettering that is used, whether for notes, titles or headings, must be clear
and easy to read.
• Good use of lettering will not only give information but can improve the
presentation of the drawing.
• Faint guide lines could be drawn to help you practice the letters and numbers.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
1 2 3 4 5 6 7 8 9 10 11
• The size of the letters depends on the size of the drawing paper.
• For A1, A2 and A3 sized paper, the letters should be between 7 mm
and 4 mm.
• For A4 sized paper the letters should be between 5 mm and 3 mm
• The British Standard 1192 sets the following recommendations.
• Job Title and number
• Name and Address of issuing firm or practice
• Description of the drawing
• Date the drawing was completed
• Author of drawing
• Checker of the drawing
• Drawing number
• Many construction firms have their drawing paper pre-printed with a
• The panel should be at the bottom right hand corner of the drawing.
J & M Builders
Drawing No 235
W R Smith
Scale 1:100 March 2003
Title Panels Drawn CPR
• Abbreviations are a simple way of conveying information on
drawings, reducing words to first letters, e.g. rain water pipe
• They allow the maximum information to be included on the drawing
in a concise way.
• Abbreviations have to be used in context e.g. MS stands for Mild
Steel in the context of construction but it could also be an
abbreviation for some other word in another situation.
• Avoid making up your own abbreviations as these can lead to
• Aggregate agg • Copper cu
• Air brick Ab • Damp proof course dpc
• Aluminium al • Discharge pipe DP
• Asbestos asb • Foundation fdn
• Asphalt asph • Hardcore hc
• Bitumen bit • Hardboard hdbd
• Boarding bdg • Hardwood hwd
• Brickwork bwk • Inspection chamber IC
• BS Beam BSB • Insulation insul
• Building bldg • Tongued and grooved t&g
• Cast iron CI • Joist jst
• Cement ct • Plasterboard pbd
• Column col • Reinforced conc RC
• Concrete conc
• These are small standard pictures used to reduce
the amount of drawing detail required on individual
• Abbreviations and graphical symbols are often used
together to give complete information.
Representation of components -
Sink Bath Bidet Toilet Hot & Cold Cold water Hot water Stop
Water drain Cistern Cylinder valve
Drain or Foul water Rain water Surface Rainwater Gulley
Sewer Flow head water outlet
Radiator Towel rail Boiler Cooker Pump