2.1 Example of what can happen if site elements are not fully related. The manhole cover relates to neither the paving slabs nor the brick pavings
The types of drawings which make up the complete set having now been identified, the next two chapters look at them in sequence to see the sort of information that each should contain.
The location drawing
The drawings falling into this category will normally include:
• floor plans at all levels
• reflected ceiling plan at all levels
• foundation plan
• external elevations
• general sections and/or sectional elevations
• location sections.
The functions of the site plan are to show:
The location of the building (or buildings) in relation to its surroundings.
The topography of the site, with both existing and finished levels.
Buildings to be demolished or removed. The extent of earthworks, including cutting and filling, and the provision of banks and retaining walls.
Roads, footpaths, hardstandings and paved areas. Planting.
The layout of external service runs, including drainage, water, gas, electricity, telephone etc. The layout of external lighting. Fencing, walls and gates. The location of miscellaneous external components—bollards, litter bins, etc.
These are multifarious functions, and some consideration has to be given to the desirability of elementalising them on to different drawings. The problem with site plans, however, is that these functions are closely interrelated. Incoming services may well share duct runs, if not the ducts themselves, which in turn will probably be related to the road or footpath systems; manhole covers will need to be related to paving layouts if an untidy and unplanned appearance is not to result (2.1).
There is a case for recording demolitions and earth-movement on separate drawings. These are after all self-contained activities which will precede the other site works. Indeed, they may well form the subject of separate contracts, and will often be carried out before other aspects of the site works have been finalised. Similarly, pavings are a finishing element which may benefit from separation into a drawing associated with service runs (and more particularly any manholes or inspection chambers within them). The remaining site works, however, are best recorded on a single drawing. If problems of clarity and legibility seem likely to arise by virtue of the work being unduly complicated then common sense will dictate either further elementalisation or producing the drawing at an appropriately generous scale.
Most site plans that are unduly cluttered and difficult to read suffer from two faults:
1. They are drawn at too small a scale for the information they are required to carry.
2. They attempt to include detailed information—large scale details of road construction are a frequent example—which apart from crowding the sheet would more logically appear separately among the assembly information of which they clearly form part.
Figure 2.2 is a good example of how not to do it. There is clearly no room for the extraneous assembly information on what should be regarded solely as a location drawing, and it is interesting to speculate on the reasoning that led to it being there. In most cases, it appears for one of two reasons. The first is that the detail was an afterthought, and since no provision had been made for its inclusion elsewhere in the set, it seemed providential that the site plan had this bit of space in one corner. The second arises in the belief that it helps the builder to have everything on the one sheet.
This latter misconception extends over a much wider field of building communication than the site plan, and it cannot be refuted too strongly. No single document can ever be made to hold all the information necessary to define a single building element, let alone an entire building. If to place the assembly section of the road on the same sheet as its plan layout was deemed to be helpful in this instance, then why not the specification of the asphalt and the dimensions of the concrete kerb as well? The road cannot be constructed, or indeed priced by an estimator, without them. The essential art in building documentation is not the pursuit of a demonstrably mythical complete and perfect drawing, but the provision of a logical search pattern which will enable the user to find and assemble all the relevant information rapidly and comprehensively.
Figure 2.3—taken from part of the site plan for a complex of buildings—illustrates some of the points made above.
There are three situations to consider:
• The location drawing designed to show a single building element, and what it should contain.
• The location drawing designed to be complete in itself—ie a drawing which in CI/SfB table 1 terminology would be described as 'The project in general' and coded (—). (Clearly this type of drawing would only arise on the smallest and simplest of projects.)
• The basic location drawing, the drawing which provides the fundamental and minimal information which will appear as the framework for each individual elemental plan—the basic negative, in fact, from which future copy negatives containing elemental information will be taken.
Since the latter has a substantial bearing on the other two, it will be dealt with first.
The basic floor plan: Let us assume that you are to prepare a set of working drawings for a building project and that, by means of techniques to be discussed in a later chapter, you have decided that the floor plans will be elementalised in the following manner:
(2-) Primary elements (3-) Secondary elements (5-) Services (piped and ducted) (6-) Services (electrical) (7-) Fittings.
You will no doubt consider what common features of the plan will need to appear in all five drawings, with a view to drawing them once only as a master—or basic—sheet, and taking five copy negatives from this master for subsequent elaboration into the respective elemental drawings. (The same principle applies of course if the drawings are being produced by CAD. The only difference here is that the elemental plant will be prepared as layers, to be recalled and combined with the base layer as required. But see chapter 4, where this is discussed in greater detail.)
If you draw less than this common minimum on your basic negative you will be faced with a five-fold repair of your omission in due course. If you draw more than the minimum you will need to erase the surplus from subsequent copy negatives, or allow them to carry superfluous and possibly misleading information. (Both these tasks are of course simplified if CAD is being used, but here again the general principle holds good.)
It is clearly important that the information carried by the basic negative, like the amount of lather specified in
2.3 A typical site plan. Information is given about new and existing levels, as well as directions as to where other information may be found. (The information about levels is included because the plan is at a sufficiently large scale, and the small amount of earth moving makes it unlikely to form a separate contract—a good example of common sense prevailing over a more doctrinaire approach)
the old shaving soap advertisement, shall be not too little, not too much, but just right. See below for a check list of what this drawing should contain, and a list of those items which more often than not get added to the original needlessly and superfluously, to the subsequent inconvenience of everyone.
To be included:
• Main openings in walls (ie doors and windows)
• Main openings in partitions (doors)
• Room names and numbers
• Grid references (when applicable)
• Fixed furniture (including loose furniture where its disposition in a room is in practice predetermined—eg desks set out on a modular grid etc)
• Sanitary fittings
Items which tend to be included but should not be:
• Details of construction—eg cavity wall construction
• Hatching or shading
• Loose furniture where its disposition is not predetermined
• Section indications.
Figure 2.4 gives an idea of what should be aimed at. Note that a uniform line thickness is used throughout, and that this is the middle of the three line thicknesses recommended in chapter 4. (Only the furniture carries a lesser weight in recognition of its non-building status.)
It is not the function of the basic drawing to differentiate between different elements, or to give differing values to them by graphical means. This will be done on the elemental drawings when emphasis may be given to the appropriate element by thickening the relevant lines.
The elemental floor plan: Generally speaking, if a project needs to be dealt with elementally then it will need to be separated into most or all of the following:
(2-) Primary elements
(3-) Secondary elements—possibly sub-divided into:
(35) suspended ceilings (4-) Finishes—possibly sub-divided into:
(42) internal finishes
(43) floor finishes (45) ceiling finishes
*(5-) Services—possibly sub-divided into any or all of the various constituent services
*(6-) Installations—possibly sub-divided into:
(64) communications (7-) Fixtures
(8-) Loose equipment.
* Likely to be produced by other than the architect.
In other words, the breakdown is into the primary facets of CI/SfB table 1, and only in one or two special instances is it sometimes necessary to go any deeper. The reasons for this are apparent from a common-sense appraisal of the reason for elementalising the location plans in the first place—the desire to produce simple uncluttered drawings upon which different types of information will not be laid illegibly and confusingly one upon the other. If you consider the possible sub-divisions of the primary element facet it will be apparent that any drawn or annotated information about (21) external walls is unlikely to conflict with information about (22) internal walls or (23) floor construction. The different elements are physically separated on the drawing, and complete legibility may be maintained even though they share the same sheet of paper. Similarly (31) external openings are unlikely to conflict with (32) internal openings, and both may appear on the same drawing under the generic coding of
The problems begin to arise when it comes to ceilings, services and finishes. Some consideration must be given to the best method of documenting these, for boundaries tend to overlap and clear thinking is essential.
With regard to finishes, the practice of laboriously covering the floor plan with descriptive wall, floor and ceiling finishes on a room-by-room basis is not to be recommended. It is impossible for the plan to give detailed enough information without exhaustive (and exhausting) annotation. (See the attempt made to convey information about room 1/9 in fig 2.5). A system of coded reference back to a written schedule is a more practical alternative, as shown in room 1/18 in the same illustration. The references A/7, B/3 and B/2 relate to a vocabulary of finishes given separately in written form, where the repetitive nature of the relatively few types of finish involved makes it possible to record them in detail without too much time consuming room-by-room annotation.
Non-graphical room-by-room scheduling is a more satisfactory alternative. It is easy to produce and to refer to, and a lot of information may be conveyed by it. It has its disadvantages, the main one being the difficulty of relating the written description to an actual wall area or door surface but on the whole it is a reasonably effective method (2.6).
Of course, a description such as 'Two coats of emulsion' is helpful only to the estimator. Ultimately, somebody is going to ask 'what colour?' and a method of documentation which does not offer facilities for telling him concisely (let alone the possibility of explaining that you want the chimney breast in a different colour from
Was this article helpful?