This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol1", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
[Contributed by R. W. Carden, A.R.I.B.A.)
The subject of working drawings is one to which a draughtsman cannot give too much attention, for accurate plans and details are absolute essentials for the production of good building. It is well to bear in mind that working drawings are working drawings and not pictures. They should merely aim at being accurate diagrams setting forth exactly the work which is required to be done, with such dimensions as are necessary clearly figured on the drawings, and the conventional colours employed to indicate materials whenever they will aid in expressing the architect's intention. Anything beyond this is not only a waste of time, but is likely to mislead the contractor and his workmen. Violet shadows and brown ink may possibly appeal to the client, especially when used in conjunction with pale green lettering, but the builder is rarely susceptible to "art," and merely sees in the drawings put into his hands something which will explain and supplement the specification.
In all such drawings the utmost care and cleanliness is required, for dirty T-squares and set-squares mean too much use of the indiarubber, and too much india-rubber means spoiling the surface of the paper, and leads to blurred lines and colours. Beyond the primary precaution of cleaning all instruments, it is advisable to so set out drawings that pencilling and inking are begun at the left-hand top corner of the paper, and the work continued across and downwards, so as to avoid blurring by repeatedly passing the T-square and angles over finished portions of the drawing.
For all ordinary purposes working drawings may be divided under three heads: drawings to the scale of 1/8 inch to a foot, drawings to the scale of 1/2 inch to a foot, and full-size details. Of these by far the most important are the first, as they constitute the chief contract drawings and include plans of each floor (and of roof and foundations very frequently also), elevations of each front, and at least two sections through the whole building. Among the contract drawings should be included a block plan - to a convenient scale, or as required by the local regulations - and drawings to the scale of 1/2 inch to the foot of any portion of the building which may seem to require more detailed explanation. These latter, however, come under the second head.
Should the building be a large one, it will be found advisable to prepare the contract drawings on canvas backed paper, and to have them bound round the edges with silk ribbon. It is surprising the amount of knocking about and rough handling these drawings have to suffer during the progress of a contract. Concerning the actual drawings, there is little to say beyond emphasising the necessity for careful thought and accuracy. It is useless to place a 14-inch wall and fireplace on the first floor with only a 5 1/2-inch partition to carry it on the ground floor, and it is wisest to build on paper as the contractor will in material, beginning from the foundations and working carefully upwards, drawing a plan, section, and elevation in turn until the whole is complete in pencil. For instance, fireplaces below must find room enough in the chimney breasts above for their flues, and stairs must be sufficiently given in detail for no doubts to arise as to headroom.
The principal object of 1/8 scale drawings is to present a general scheme of the whole work with all the sizes of the various rooms, positions of openings, thicknesses of walls and chief features. It is of the utmost importance, therefore, that all the dimensions be fully worked out and figured clearly on the plans. All part-dimensions, when added together, must agree with the total through-dimension, and these are probably best worked out partly by measurements on the plan and partly by calculation on waste paper. For instance, if a house have parallel sides each set of dimensions right across must total the same; but if each part dimension were figured on exactly to what it appeared to measure on the plan errors would undoubtedly arise, as with a scale of 1/96 full size it is impossible to plot accurately to every half-inch, so that these dimensions have to be adjusted and corrected by the known through-dimension. These 1/8 scale drawings are inked in and fully coloured up, whether the parts shown be in plan, section, or elevation, and in the latter the courses of brick or stone are also frequently indicated, but not in such a manner as to mislead the builder into taking the lines so added to the drawing to mean something else. The section lines should be very clearly and correctly marked on every plan, and are best represented by a bold line of alternate dots and dashes; for if an ordinary solid line is used it is liable to confuse the plan and suggest a difference of level. All the dimensions - which, as already said, must agree always with the totals - should be printed on in red ink, with limiting lines to show clearly and exactly how much of the plan is included in the given dimension.
The "1/2-inch details" include almost every portion of the building, and a good set of 1/2-inch working drawings would illustrate every door, window, staircase, roof-truss, gable, skylight, etc. etc., contained therein. As already hinted, some of the drawings to this scale are frequently made part of the contract drawings, so that important features are irrevocable in nearly all their details before the building is begun. This is of the utmost importance always, but especially so when an architect is obliged to give the work to a contractor who is known to have cut down his estimate to a ridiculously low figure. In such a case the contractor will very possibly be always on the watch for omissions from specification or contract drawing to enable him to claim extras, and so make up by profit on these for lack of profit on the contract. If, however, he is made to sign, among the other drawings, a 1/2-inch drawing of one bay of the front, or of any important panelling in the hall, or a marble terrace or whatever elaborate features there may be included in the work, it will deprive him of half his opportunities for claiming extras, as naturally he cannot dispute his own signature.