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1.12 The complete primary structure of building drawings information demonstrating them. Figure 1.13, taken almost at random from such a drawing, shows the disadvantages.

The sheet is cluttered with information, making it extremely difficult to read. The notes and references fill every available corner, and in an attempt to crowd too much information into too small a compass, the draughtsman has had to resort to a lettering style of microscopic dimensions. Any alteration to it would be difficult both to achieve and to identify. (Figure 1.2 also illustrates the defects inherent in the 'one drawing' approach.)

This is a case of one drawing attempting to do the work of several, and simplicity, legibility and common sense would all be better served if there were several drawings to replace it. Let us consider the various ways in which the crowded information might be distributed.

The Department of the Environment Report 'Structuring Project Information' lists no fewer than nine separate non-traditional systems that include in their make-up some degree of information structuring. The seventies had seen a wide-spread and largely unco-ordinated experimentation in building communications techniques, generated by an increasing demand on the resources of an over-stretched profession and building industry, and a growing awareness of the inefficiency and waste of time on building sites being caused by inadequate documentation. Not all these systems were at that time sufficiently well tested to allow a genuine evaluation of their merits.

Now, some twenty years later, we are in a better position to obtain a proper perspective of the field, and the problem becomes somewhat clearer. Some of the communications systems then presenting themselves for consideration are now seen to be so closely associated with the requirements of specific organisations or constructional systems that they lack universal applicability. Others, reliant upon a more radical re-fashioning of the bills of quantities than is envisaged here, offer possible pointers to the future and are discussed later.

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1.15 Elemental version of 1.13 dealing with the floor (scale 1:50)

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All accept the primary structuring of drawn information represented in this book by the location/component/assembly format. Where they tend to diverge is in their approach to secondary structuring, and their methods of identifying and coding it.

The building operation, and indeed the completed building, may be considered in a number of ways. You may regard it, for example, as an assemblage of different materials. To some extent the specification does just that, describing with precision the type of sand, the type of cement and the size of aggregate to be used, as well as describing their admixture into concrete (the point at which the bills of quantities take an interest).

You may look at it, on the other hand, as a series of different trade activities, in which case you would tend to regard as one package of information all work done by the carpenter, and as another package all work done by the plumber. Bills of quantities have traditionally been structured on these lines, the concept lying at the heart of the standard method of measurement. It has been one of the primary tasks of the Co-ordinating Committee for Project Information in its development of a common arrangement of work sections to seek out a rational method of terminology for building operations that would be acceptable to all the building disciplines.

In drawing terms, however, neither sub-division relates very happily to the architectural realities. To the quantity surveyor one cubic metre of concrete may be very like another, but when one forms part of the foundations and another part of the roof slab it is over-simplistic to suggest that both should form part of a series of 'concrete' or 'concretor' drawings.

Drawings are by definition concerned with the perceived form of the building, and if we are to sub-divide them then a breakdown into the different elements of their form is more logical than an attempt to classify them by either material or trade subdivisions.

So let us return to the cluttered example Shown in 1.13 and separate it into three elements chosen at random, collecting information about the walls on to one drawing, the floor on another and the doors on a third (1.14,1.15 and 1.16).

At once we can see what we are doing. The notes and references to other drawings are relatively few and sparsely distributed, so that they catch the eye, and plenty of space is left for further annotation should this become desirable during the course of the project. Furthermore, to anyone who knows how this particular set of drawings is sub-divided the search pattern for any aspect of the building is straightforward. If he wants to know about windows he can go straight to the location drawing dealing with windows, from which point the search pattern described previously can proceed within the narrow confines of window information. The general search pattern, shown diagramatically in 1.17 now follows a series of paths, each related to a specific aspect of the building (1.18).

The advantages of this are two-fold. In the first place the designer now has a framework upon which to display his information and in the second place the user has an authoritative guide through the informational labyrinth.

Structuring by building element: Within the framework of a primary structuring by information type, the information to be conveyed is sub-divided by building element and this constitutes the secondary structuring of the drawing set.

To establish the possible means of achieving this we should start by looking at the various ways in which the building fabric may be regarded. Consider the diagram in 1.19.

It is difficult to visualise any space-enclosing structure, no matter how primitive, which did not possess elements falling within one or other of these four categories. A little thought, however, will suggest that

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element a element b element c element d etc.

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