WORKING DRAWINGS HANDBOOK, Fourth Edition

Working Drawings Handbook

drawings are termed ‘general arrangement drawings’.
The term ‘location drawing’ has long been established
within the architectural profession and the mnemonic
SLAC (schedule, location, assembly, component) is in
common use. Nevertheless, it seems likely that the CPI
terminology will become increasingly known and used.
The term ‘general arrangement’ has in any case long
been used in the engineering disciplines and has
therefore been used throughout the remainder of
this book.

Into this neatly classified system must now be
introduced that somewhat hybrid creature, the
schedule. It must be made clear at the outset that
the term ‘schedule’ here referred to is confined to
basic lists of information—primarily about
components—which are more readily set out in this
manner than on the drawings. (The Schedule of
Works, as envisaged in the CPI documents for
smaller projects, has a different function, more akin
to the bills of quantities.)

The idea of using written schedules, or lists of
information, exists in most information systems and has
its source in a variety of motives, not all of them
necessarily valid. It is assumed that they are economical
of drawing office time; that quantity surveyors,
contractors and suppliers alike all welcome them; and
that they provide a ready check that the information
conveyed is comprehensive.

These reasons do not always stand up to close
examination. Schedules are only economical if they are
simpler than the drawings they replace; the architect
should not necessarily be doing other people’s jobs for
them; suppliers more often than not produce their own
schedules because the architect’s schedule is not in a
form which they find usable; and some schedules
attempt to provide so much information in so
complicated a form that mistakes and omissions
readily occur.

Nevertheless, they have a role to play and used sensibly

and with forethought they form an essential element in

the information package.

Some principles affecting scheduling

Their primary function is to identify and list components

possessing common characteristics—e.g. windows,

doors, manhole covers, etc.

They should not attempt to provide comprehensive

information about the component; they should serve

rather as an index to where the relevant information

may be found.

They should initiate a simple search pattern for the

retrieval of component, sub-component and assembly

information.

They are only worth providing if the component in

question has more than one variable. For instance, if

you have windows of three different sizes which are

identical in every other respect, then size is the only

variable and you may as well write ‘Window Type 1’ on

the general arrangement plan as ‘Window no. 1’. But if

each window size may be fixed into either a brick wall or

a pre-cast concrete panel then the assembly information

required is a second variable.

Window Type 1 may be combined with jamb detail type 1

or type 2, and it is for this greater degree of complexity

that it is preferable to prepare a schedule.

The great virtue of the schedule is that it can direct you

to a vast amount of information about a given

component in a way that would be impossible by any

system of direct referencing from a general arrangement

drawing. Consider a window—thirty-seventh, shall we

say, of fifty-one on the second floor of a multi-storey

block of offices. The method chosen for giving it a

unique reference is unimportant for the moment—W2/

is as good a piece of shorthand as any for the

purpose—but it is obvious that this simple means of

identification may be shown equally on a drawing or a

schedule (1.6).