This section is from the book "A Treatise On Architecture And Building Construction Vol4: Plumbing And Gas-Fitting, Heating And Ventilation, Painting And Decorating, Estimating And Calculating Quantities", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
Sheathing. To calculate sheathing or rough flooring (which is not matched), find the number of feet B. M. required to cover the surface, making no deductions for door or window openings, for what is gained in openings is lost in waste. If the sheathing is laid horizontally, only the actual measurement is necessary; but if it is laid diagonally, add 8 or 10 per cent. to the actual area.
Flooring. In estimating matched flooring, a square foot of 7/8-inch stuff is considered to be 1 foot B. M. If the flooring is 3 inches or more in width, add one-quarter to the actual number of board feet, to allow for waste of material in forming the tongue and groove; if less than 3 inches wide, add one-third. Flooring of 1 1/8-inch finished thickness is considered to be 1 1/4 inches thick, and for calculating it the following rule may be used: Increase the surface measure 50 per cent. (This consists of 25 per cent, for extra thickness over 1 inch, and 25 per cent., for waste in tonguing and grooving.) To this amount add 5 per cent, for waste in handling and fitting.
20. Weather hoarding or siding is usually measured by the superficial foot. No deduction should be made for ordinary window or door openings, as these usually balance the waste in cutting and fitting. Careful attention must be given to the allowance for lap. If 6-inch, nominal width (actual width, 5 5/8 inches), siding, laid with 1-inch lap, is used, add one-quarter to the actual area, in order to obtain the number of square feet of siding required. If 4-inch stuff is used, add one-third to the actual area. When, as above noted, no allowance is made for openings, the corner and baseboards need not be figured separately.
21. Cornices may be measured by the running foot, the molded and plain members being taken separately. A good method of figuring cornices is as follows: Measure the girth, or outline, and allow 1 cent for each inch of girth, per lineal foot. This price will pay for material and for setting, the cost of the mill work being estimated at 50 per cent.
Cost Per Square Foot. For all classes of materials which enter into the general framing and covering of a building, a close estimate may be made by analyzing the cost per square foot of surface; that is, the cost of labor and materials-studs and sheathing in walls, joists and flooring in floors, etc.-required for a definite area, should be closely determined, and this cost, divided by the area considered, will give the price per square foot. If the corresponding whole area is multiplied by the figure thus obtained, the result will, of course, be the cost of that portion of the work. While it is usual to adopt a uniform rate for the various grades of work, a careful analysis will show that roof sheathing in place costs more than wall sheathing, owing to its position; and that the studs in walls and partitions cost more than floor joists, as they are lighter and require more handling.
The following example shows how to determine the cost per square foot of flooring, and indicates the general method to be pursued in like cases. The area used in the calculation is a square, or 100 square feet. The cost of labor is estimated at 50 per cent. of that of the materials, which experience has shown to be a very close approximation to the actual cost of general carpenter work.
Cost of Finished Floor per Square.
Joists, hemlock, 8 pieces, 3"xl0"xl0', 200 ft. B. M., at $14 per M................
Bridging, hemlock, 7 sets, 2"x3"xl' 4", 9 ft. B. M., at $14 per M................
Rough flooring, hemlock, 7/8 inch thick, laid diagonally, 100 ft. +25 ft. +10 ft, 135 ft. B. M., at $17 per M..................
Finished flooring, white pine, 7/8 inch thick, 125 ft. B. M., at $22 per M.............
Nails, (about) 3 lb. at $1.80 per 100 lb.........
Labor, 50 per cent. of cost of materials......
Total cost for 100 sq. ft...........
Cost per square foot, $12.03÷100 = 12 cents.
A similar method may be followed in estimating the cost of interior finish, paneling, doors, etc.
23. The quantity of material that a workman will put in place in a day is very uncertain, depending upon the skill of the artisan, his rapidity of working, and the ease or difficulty of the work, all somewhat modified by numerous accidental circumstances. The subjoined figures, while founded on information gained by many years of experience, are only intended to give an idea of the relative quantities, and are not a standard to be adhered to in all cases. The estimates are based on a 9-hour day, and wages at $2.25 per day. If the hours or pay are less or greater, the results will be correspondingly diminished or increased. Unless otherwise noted, the figures represent the labor of two men working together.