Working Drawings Handbook
Where hatching is used it should be kept simple in
convention. Often a simple diagonal hatching, with the
diagonals running in different directions, will suffice to
illustrate the function of two components of the same
material, without requiring that the user look up some
vast code book to see what the material is. This is
clarified in the accompanying notes.
Gridded hatching, where the grid is parallel to the
axes of the element being hatched, is confusing to
interpret.
The foregoing comments apply equally to hatching
applied during CAD draughting, even though such
hatching is simple and rapid to apply.
Some conventions in common use, simplified from their
original sources, are given in Appendix 3 but their use
should be very much conditioned by the comments
above.
Electrical symbols
The architect frequently becomes involved in the
production of electrical layout drawings, particularly on
smaller projects where no M & E consultant is engaged,
and Appendix 4 gives some of the more commonly used
symbols in general practice.
Two points may usefully be made about the method of
showing wiring links between switch and fitting. In the
first place, of course, any such representation on
the drawing is purely diagrammatic; no attempt need be
made to indicate the precise route the wiring should
take. (If ducted provision has been made the fact should
be noted on the drawing and the ducting shown on the
appropriate builder’s work drawing.)
In the second place, the links are far better drawn
curved than in straight lines which are liable to conflict
with other building elements (see 2.7in Chapter 2).
Non-active lines
Lines on a drawing which delineate the actual building
fabric are termed ‘active lines’. Those lines which are
essential to our understanding of the drawing, such as
grid lines, dimension lines, direction arrows, etc. are
termed ‘non-active’ lines.Recommended conventions for non-active lines are
given in Appendix 5.Templates
Various plastic cut-out templates are on the market,
covering many of the symbols given in the appendices.
Templates are also available for the production of circles
and ellipses and for drawing sanitary fittings.Such templates are a time-saving aid, even though one
of the corollaries of Murphy’s law ensures that the
symbol you really need is missing from that particular
template. A word of warning should be added about the
indiscriminate use of templates for sanitary fittings,
where it is dangerously easy to fool yourself about
dimensions. Some manufacturers of sanitary fittings
produce their own templates, and these of course give
an accurate representation of the particular fitting
specified. However, in their absence it is safer to draw
the fitting to its true overall dimensions taken from the
manufacturer’s catalogue than to rely on a standard
template which may deceive you into a situation where
the toilet door fouls the lavatory basin which arrived on
site larger than you had drawn it. Figure 4.8gives an
example of a typical template.Block libraries (templates)
The CAD equivalent of drawing templates is the block
library.Dedicated architectural CAD programs will come
complete with their own 2D and 3D block and symbol
libraries. These programs will allow you to select