We have covered the structure of a set of working

drawings, the hierarchic progression of location,

assembly, component, sub-component drawings and

schedules. We now have to look at how the drawings

themselves are to be prepared, in a form that will be

economical of drawing time and will enable multiple

copies to be taken for the use of the contractor,

sub-contractors, quantity surveyor and others.

There are two primary methods for producing the

originals:

1 They may be created on a computer using a CAD

program before being sent to a printer or plotter

2 They may be drawn manually, using pen or pencil

techniques, which until a few years ago were the

only options available.

Since CAD is the predominant method now in use we

shall deal with it first.

Computer-Aided Draughting

At its simplest CAD is little more than an electronic

drawing board. Individual drawing files are created from

lines, circles and text, each file being an electronic

image of the paper drawing that will be created from it.

Individual lines and circles are assigned a pen width, a

colour and a linetype of dashes and dots but little more

than that. At the other end of the spectrum some CAD

(Computer-Aided Design) programs aim to provide all

the tools necessary to designthe project, whilst all

necessary construction drawings are generated

automatically.

A drawing file created by CAD has the potential to be far

more than just a collection of paper drawings stored on

computer. Used properly, it can be a database

describing a building in its entirety as a 3D model, from

which plans, elevations and sections can be generated

as and when needed, at any scale, and showing any

sub-set of information. The drawing file would be created

from walls and windows rather than lines and circles,

and these walls and windows might have their size,

weight, cost, materials and manufacturer details

attached. The same drawing file might also be used to

generate isometric or axonometric diagrams, or photo-

realistic coloured perspectives. The same file might be

used at all stages of design and construction, from initial

proposals and discussions with the client through

4

CHAPTER

4 Drawing the set