Using Scale in DrawingsStudents Notes

Bricklayers, as skilled and responsible construction workers, must be able to read drawings accurately. These notes suggest some first steps towards the development of this essential skill. Students should also take every opportunity to study drawings and wherever possible compare them with a building under construction.

ScalesIt 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 real item -:

• 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.

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The main scales or ratios used in construction drawings are-:

1:1 Full size used for unusual details or templates

1:21:5 Complicated building details1:10

1:201:50 Plans, elevations and sections1:1001:200

1:2001:500 Site plans1:1250

1:1250 Block or location plans1:2500

Task 1 Complete the table below, filling in the missing scales

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Scale Drawing is: Scale Drawing is:1:1 The same size as the object 1:100 100 times smaller than the

object1:5 5 times smaller than the object 1:200

1:10 1:500 500 times smaller than the object

1:20 20 times smaller than the object 1:1250 1250 times smaller than the object

1:50

Task 2 (If the number used in the scale is multiplied by the measurements used to draw the plan, the actual measurements can be found )

Look these drawings of two walls. A scale of 1:50 has been used for Wall A whereas a scale of 1:100 has been used for Wall B. They both look the same on paper but in real life they would be very different sizes!

What is the height in real life?25mm × 50 = 1250mm

Divide by 1000 to convert mm to m = 1.25m

What is the height in real life? _____ mmThe bigger wall in real life is Wall _____

Try thisWrite in the scale that would make Wall C 5 times bigger than Wall B in real life.

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80m on site

120m on site1 on drawing = 2500on site

SCALE RULE

Hatching

Hatching is a term given to the markings on a cross sectional drawing used to indicate the material that it is constructed of.

They are official British Standards and can be found in BS: 1192 which controls drawing practice across all sections of the Construction Industry

Task 3 From the powerpoint slide complete the missing hatching titles.

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Abbreviations

Abbreviations are a simple way of conveying information on drawings, reducing words to first letters, e.g. rain water pipe becomes R.W.P. 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 confusion.

AbbreviationsAggregate agg Air brick Ab Graphical SybolsAluminium alAsbestos asbAsphalt asphBitumen bitBoarding bdgBrickwork bwkBS Beam BSBBuilding bldgCast iron CICement ctColumn colConcrete concCopper cuDamp proof course dpcDischarge pipe DPFoundation fdnHardcore hcHardboard hdbdHardwood hwdInspection chamber ICInsulation insulTongued and grooved t&gJoist jstPlasterboard pbd

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Reinforced conc RC

Graphical Symbols

These are small standard pictures used to reduce the amount of drawing detail required on individual drawings.

Abbreviations and graphical symbols are often used together to give complete information.

Representation of components - fittings

Sink Bath Bidet Toilet

Hot & Cold Cold water Hot Water Stop ValveWater drain off Cistern Cylinder

Radiator Towel rail Boiler Cooker Pump

Drain or Sewer Flow Foul water Rainwater head

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Surface water Rainwater outlet Gulley

Task 4

Complete the following section through the foundation of a building up to window level with the correct hatchings.

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Working Drawings

A working drawing and written specification should contain the total information requiredFor a building team to convert the architects proposed building into a completed structure.

To enable this to happen the following information should be found in the following locations.

ELEVATIONS:

1. External finish to walls and roof

2. Position of window and door openings

Scale used 1:200, 1:100, 1:50

PLANS:

1. Overall dimensions of the building

2. Position of internal walls, room sizes door and window openings

3. Position of fitments, baths, sinks toilets, stairs etcScale used 1:200, 1:100, 1:50

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SECTIONS:

1. Provide vertical dimensions

2. Provide constructional details of foundations, floors, walls, roof, damp proof membranes and ground levels

SITE PLAN:

1. Position of the building inrelation to the site surroundingsi.e. adjoining buildings, roads, boundaries, etc.

2. Provision of access

3. Drains and main sewer

4. North point

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BLOCK PLAN:

1. Location of site in relation to surrounding district. This is taken from local authority’s ordance survey map.

COMPONENT DRAWINGS:

1. These show the basic sizes of standard components such as doors, windows and kitchen fitments. scales most commonly used are 1:100, 1: 50, 1: 20.

LEGAL or TITLE PANEL:10

1. Site Address

2. Scales used on drawing

3. Drawing Number

4. Client

5. Date of drawing

DETAIL DRAWING:

These drawings will include every detail required to make the product. The information from these details is used to manufacture various components .These drawings are usually produced by the architect and are produced in scales ranging from 1:1, 1;5, or 1:10.

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ASSEMBLY DRAWING:

These drawings are very important to the builder. They show in detail how the architect requires the construction to be constructed and what materials should be used .The scales usually used for these drawings are 1:20, 1:10, 1:5 and should be fully dimensioned and annotated.

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Key Points

• Select drawing required consultingIndex if available

• Ensure it is the latest amended version• First, get an overall picture before looking at details.• Check the sum of intermediate dimensions equals the

overall dimension• Do not scale from drawings• Take every opportunity to compare drawings with the

current construction