General arrangement plansprimary elements

Note that CI/SfB Table 1 offers the following choice within the general summary code (2-):

(21) Walls, external walls

(22) Internal walls, partitions

(23) Floors, galleries

(24) Stairs, ramps

(27) Roofs

(28) Building frames, other primary elements.

In the larger of the two buildings—Project A—the decision was made to confine the architect's information about primary elements to a single (2-) drawing. A decision was made at about the same time in relation to the smaller and simpler Project B to sub-divide the primary elements to a greater degree. Since the reasons for arriving at these decisions were different in each case, they serve to illustrate the importance of thinking about what you are trying to achieve before actually starting to draw.

On Project A, which had a reinforced concrete frame and floor slabs, and which enjoyed the services of a structural consultant, it was deemed unnecessary, not to say inadvisable, for the architect's drawings to give constructional information about structural elements which were clearly the responsibility of the structural engineer. So floors (23), stairs (24), roofs (27) and frames (28), whilst appearing on the architect's primary element drawing (2-), nevertheless, remain in outline only. Against each of these elements appears a reference to the fact that the appropriate structural engineer's drawing should be consulted, thus satisfying the second of the two basic functions of a general arrangement plan—either to locate the element it deals with or to state where it may be found.

Of the other primary elements—and in this particular instance the walls and partitions are the primary consideration—the information given about them consists of statements as to where they are to be placed (i.e. dimensions from known reference points—sensibly, in this instance the structural grid); what they consist of (i.e. notes on their materials or reference back to more detailed specification information); and where further information about them may be found (i.e. coded references to relevant assembly details). The primary elements dealt with on this particular drawing, as distinct from primary elements dealt with on other general arrangement drawings, are identified by being emphasised in a heavier line than that used for the rest of the drawing.

The comparable (2-) drawing for the smaller of the two projects had obvious points of similarity but the reasoning behind its production was somewhat different. The building was of simple two-storeyed load-bearing brick construction, with simply supported timber roof and floor joists and timber staircase. There was no structural engineer, so the design and detailing of these structural elements devolved upon the architect.

Two primary elements drawings were therefore produced—a generic (--) drawing covering both external walls and internal partitions and a (27) drawing covering the roof construction. Both are shown in 2.12 and 2.13.

It is worth making a point about the way in which the brickwork was described in each case because it illustrates the fundamentally common sense way in which all such decisions should be handled (2.14). In the larger building there were four different types of brickwork involved. These were:

1 A Class II engineering brick in cement mortar, used in manholes and certain works below ground.

2 A common brick to BS 3921 Part II, laid in a 1:1:6 mortar mix and used generally for all backings.

3 A sand-lime facing to BS 187, laid in 1:1:6 mortar to a Flemish bond and used generally as a facing brick to wall panels.

4 A hand-made fired clay facing brick, used in certain featured areas on the entrance facade and laid to a decorative pattern.

A schedule of brickwork types formed part of the specification, in which each type was fully identified and described. The reference Fg1/3 on the drawing would

Simple Building Drawing

2.12 Both primary and secondary elements are combined in this small building under the code (--) The Project in General. The simple nature of the building and the large scale of the drawing, made possible by its modest size, makes this feasible

Roof Construction Drawing

2.13 For clarity the roof construction layout is separated and coded (27)

Sfb Drawing Codes

2.14 Elevations as a guide to external finishes not readily described in detail by other means indicate that it is the third type of brickwork in that schedule, which given that the project included the full CI/SfB nomenclature as part of its documentation would be found in the Fg (bricks and blocks) section of that specification. The intricacies of full CI/SfB coding is of course unnecessary unless so desired. 'Brickwork Type 3'would have been an equally specific identification, provided it were so described in the specification.

In the smaller project, however, only two types of brick were used—a common brick and a facing brick. So in this instance the description 'facing brick'—assuming the specification has fulfilled its proper descriptive function— was perfectly adequate.

In neither case is it likely that the routine of the drawing office was disrupted a year later by someone telephoning from site to ask 'which brick goes here?'

Figure 2.15 shows the virtues of secondary structuring of drawings and the inherent flexibility of elementalisation when used with common sense and imagination. The project in question was one of a number dealing with a similar building type, each of which involved the appointment of a nominated sub-contractor for various

Nominated Contractor

2.15 Elementalisation used flexibly in practice. The general arrangement plan gives a clear exposition of the responsibilities of one sub-contractor-—in this case the shopfitter shopfitting works. With certain elements—doors, pelmets and skirtings, for example—being carried out by the main contractor in some areas and by the shopfitter in others, it was important that the method of documentation employed should be capable of defining satisfactorily the limits of responsibility for each. It was also desirable that it should provide for separate packages of information being available upon which each could tender.

The method adopted in practice was to treat all the work of the shopfitter as a (7-) fittings element, regardless of rigid CI/SfB definitions and to record it on a (7-) general arrangement plan, while the work of the main contractor appeared on separate general arrangement plans covering (2-) primary elements, (3-) secondary elements and (4-) finishes. Assembly drawings involving the work of both main contractor and shopfitter were referenced from all the relevant general arrangement plans and were included in both packages of information.

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Responses

  • fnan
    Do general arrangement consist of walls only?
    4 months ago
  • Ausonio
    How to create general arrangement of a buildhng?
    2 months ago

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