Remember too that the building consists of more than that which can be seen above ground. One of the more useful aspects of a properly drawn set of elevations is that an indication can be given of the sub-structure, and of the building's relationship with the immediately surrounding terrain or pavings (2.17).
We have mentioned sectional elevations, and we may as well deal here with general sections also, for in this context they serve the same purpose as the elevations, in that they present a general picture of the building without necessarily providing any specific information from which it might be built. They are of particular value to the contractor when he is planning the sequence of his operations on site, and for this reason those items of particular relevance to this function—the relationships of floor levels to one another and of the building to the ground are obvious instances—must be shown adequately (2.18).
Elevations too should carry grid lines and finished floor levels. Other than that they should be simply drawn, with all visible features included but not unduly elaborated.
Windows in particular tend to be over-drawn; there is really no point in elaborating glazing bars and beads when these aspects are going to be covered much more fully on the appropriate component drawings. Brick courses merely confuse the eye. We are not dealing here with an artistic pictorial simulation of the building but with a schematic factual representation.
There are four areas where elementalisation of the elevations should be considered, particularly on larger projects:
1. They may be used to locate external openings, and this can be a helpful means of cross-reference back to the external openings schedule. All that is necessary is for the opening reference—(31)007, (31)029-to be written on the appropriate opening in elevation. The practice, sometimes attempted, of using the elevation as the actual external openings schedule is not to be recommended. More needs to be said about the average window than can sensibly be carried in a small box on a 1:200 elevation.
Such references are useful in relating a point on the elevation with its corresponding position on plan, but the elevation should never be regarded as the primary source of reference for these components. Regardless of whether or not they appear on the elevations, it is essential that the references appear on the appropriate location plans (2.19).
2. They may be used to identify the type and extent of external finishes, and this is a useful device, for it is not easy by any other means to indicate such things as patterned brickwork, the change from one type of bond or pointing to another, or soldier courses (2.20).
3. They may be used as both location drawings and schedule for cladding panels or ashlar facings (2.21).
4. They may be used to convey information about external plumbing and drainage services above ground (2.22).
Location plans in effect constitute a series of horizontal cross-sections through the building, spaced out so that one is taken at every floor level. This spacing is reasonable, since in practice the appearance of the horizontal section is most likely to differ from floor to floor, and unlikely to differ between floor and ceiling.
If a series of comparable vertical cuts were made through the building, again taking a fresh one whenever the appearance of the section changed, the result would be a very large number of sections indeed. Such vertical sections constitute a vital aspect of the information to be conveyed, yet their number must be limited to manageable proportions.
Fortunately, a large proportion of the possible sections tell us very little about the building. Figure 2.23, which reduces the cross-section through a multi-storeyed building to a diagrammatic simplicity, will explain why.
Most of it is irrelevant to our understanding. The internal elevations of those rooms which are exposed by the section cut are not a very suitable medium for describing, for example, wall finishes, since the other three walls of the room are not shown. It is true that we are shown the positions of doors in those walls, but these are shown, and indeed dimensioned, much more comprehensively on the respective floor plans.
The heights of internal door frames may be derived whenever the section line passes through an internal wall coincident with a door opening, but the height of the frame may be obtained more readily from the component drawing of the doorset of which it will form part.
The only pieces of information it carries which are not readily obtainable from other sources in fact, are the height of the window cill, the height of the parapet, the relative floor levels, and the thickness of the floor construction. Each of these items of information would be conveyed just as effectively if the section were confined to the narrow strip running through the external walls (2.24).
Since the number of potentially different wall sections will be limited, the vast number of separate cross-sectional cuts through the building at first envisaged is reduced to manageable proportions. Those strip sections may also be used as a reference point for the detailed construction information which needs to be given about window head, window cill, parapet, footings and the junctions of floors with walls, and as such they may be regarded as forming part of the location information for the project.
There is little point in attempting to use the strip sections themselves to convey this detailed information unless the building is so small, or so simple in its design, that a few such sections tell all that needs to be conveyed about the construction. In most instances the scale of the section, and the number of times it will change around the building, will make it more sensible to treat the location section in almost diagrammatic terms.
level 7 3ZL
Note that the floor levels are given, and that the vertical dimensions (for example, to window cills) are given from those floor levels to a datum (for example, the top of the last course of bricks) which is readily achievable on site, and to which the more comprehensive dimensioning contained in the subsequent details may be referred. level 6
There is no advantage in elementalising the location sections, although if CI/SfB coding is being used there is some advantage in regarding them as L (2-) drawings, thus differentiating them from the L (—)
general sections previously described and which fulfil a [eveI 5 XT7-different purpose in the set.
The points around the building at which the strip sections are taken will, of course, be indicated on the location plans (2.25).
level A X7
level 3 SZL
level 2 X7
2.24 Sectional cut confined to perimeter of building level 1 XZ
the location drawing
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