WORKING DRAWINGS HANDBOOK, Fourth Edition

Component, sub-component and assembly drawings

involve a scale of 1 : 20 being used for a wide variety of
constructions, with a scale of 1 : 5 being used where
greater detailed explanation is required—e.g. where the
exact positioning of relatively small components such as
bricks or tiles is a vital part of the information to be
conveyed.

The level of draughting ability may well be a deciding
factor when details are drawn manually. But don’t be over-
optimistic, the mere fact of drawing to a larger scale will
force you into consideration of problems which might
have been glossed over at a smaller scale. It is the
operative ultimately who will be asking the questions and
requiring the drawn answer. And he will be building full
size. (In CAD, of course, the drawing files are created full
size, and the ultimate scale is only applied when printing.)

Figures 3.14and 3.15at scales of 1 : 20 and 1 : 5,
respectively, are appropriate examples of the information

it is necessary to convey. Note that the damp course in

3.14, being a simple layer of lead-cored bituminous felt,

can be shown adequately at the smaller scale, whereas

the damp course in 3.15is a much more complex piece

of work, with all sorts of hazards should it be installed

incorrectly and so justifies its more expansive 1 : 5

treatment. With CAD of course, where the details will

generally be created full size, the same degree of detail

will exist on the drawing file, to be reproduced at any

scale deemed appropriate.

2 The information given should be limited. Perhaps

concentrated is the better word. For it is more helpful to

produce twenty assembly sections, each covering

limited portions of the structure, than to attempt an

elaborate constructional cross-section through the entire

building purporting to give detailed information about

almost everything.

Figure 3.16, reduced here from its original scale of

1 : 20, is a good example of how not to do it. All that has

been achieved is a very large sheet of paper, consisting

of an internal elevation at an inappropriately large scale

surrounded by a margin of detailing which through

necessity has been portrayed at a smaller scale than

would have been desirable. The drawing has clearly

taken a considerable time to produce. This in itself may

well have led to some frustration on the part of the

builder or the quantity surveyor, who needed urgently to

know the damp course detailing in the bottom left-hand

corner but had to wait for the gutter flashing at the top

right-hand corner to be finalised before the drawing

could be issued to him.

At the end of the day we have been shown in some

detail what happens to the construction along a more or

less arbitrary knife cut through the building at one point.

It is to be hoped that the detailing is consistent right

round the perimeter, because the manual detailer is not

going to be anxious to repeat the exercise whenever the

construction changes. Were he to do so he would find

3.14 Relatively simple detailing adequately conveyed
at a scale of 1 : 20