After the drawings have been made, the sizes of the various features and their location in the building must be definitely given by dimensions.
First and foremost, these dimensions must be made clearly and so that they can not be read incorrectly. Too much emphasis can not be laid on this statement. The figures given in the article on lettering are the most legible and best for use on working drawings. The accompanying drawings show how the dimension lines should be made. The dimension in any case means the distance from arrow point to arrow point, so care must be exercised that these arrow points belocated in exactly the right place.
When possible, keep dimensions off the object. Thus on Plate 22 the arrow points often touch two lines extending out from the plan. These are called extension lines or reference lines and are made very lightly. Extension lines are drawn through the centers of windows, doors, etc., for the purpose of locating them on the plan.
No line of the drawing and no center line should ever be used as a dimension line.
Dimensions should read from the left toward the right and from the bottom toward the top of the drawing. In any case they should read with the dimension lines, not across them. This is illustrated on the Cochran plans.
Dimensions should always be given to the face of masonry walls, to the outside of studs in outer frame walls, to the center lines of frame partitions, to the center line of beams, girders and columns and to the center line of door and window openings. In any case they must be given so as to best aid the workman who is doing the building. Give them also in such a way that variation in stock sizes of material will not affect the result.
In addition to the dimensions to centers of openings in masonry walls, the width of the opening should be given. This is necessary in getting out stone sills, steel lintels, etc.
Whenever possible, keep dimensions off of sectioned surfaces.
A careful study of the accompanying drawings will show the best ways of indicating dimensions under various circumstances. Information concerning the dimensioning of stairways, fireplaces, etc., is given with the details of those features.
It is very easy to spoil a good drawing by poorly made dimensions so the form of the figures and the shape and location of the arrow points should be carefully watched.
Notice on Plate 22 and Plate 32 how the detail dimensions are given on one line, the larger dimensions on a line outside the detail dimensions and the over-all dimensions are outside of them all whenever possible.
In general, the vertical dimensions are given on the elevations and vertical sections and the horizontal dimensions on the plans. Verify this by consulting the plates.
The plans, elevations and sections on Plates 21 to 30 give the student a comprehensive idea as to the drawings necessary for a complete graphic description of the average residence.
Of course for a cheap house where a great deal of stock material is to be used, the drawings might be much more simple, but for good work, each feature should be carefully presented.
Notice the scale at which the drawings are made and the amount of detail shown on each.
After the building is drawn up, a number of sets of the drawings must be made to supply each of the contractors with a copy and to replace those worn out on the job. These are made by placing a sheet of transparent tracing cloth over the pencil drawing and tracing all lines, notes, dimensions, etc., on the cloth in black drawing ink. This tracing is then placed in a frame over a white sensitized paper called blueprint paper and exposed to the sun or an artificial light. The light causes a chemical change in the emulsion on the paper which, immersed in water, causes the paper to turn a deep blue wherever the light has reached it. The black ink lines prevent the light from reaching the emulsion and so all lines, notes, etc., develop out white in contrast with the blue background making a very legible blueprint. After the print is washed it may be exposed to the light without causing any further chemical change.
This method of reproduction is both cheap and practical for working drawings. In all cities and towns of any size may be found blueprinting establishments, and the architect can have this work done more cheaply than he can do it himself.
Sometimes blueprints are made directly from pencil drawings on tracing paper but they are not so sharp and brilliant as those made from the cloth tracings.
When the draftsman desires some of the lines of the blueprint to show rather dimly, he traces them in diluted black ink. This allows some light to filter through and produces bluish lines which are not so prominent on the print as the white lines. These are valuable in showing brick jointing, section lining, etc.