Shiplap. Calculate the exact surface to be covered, deduct openings; then add for floors 17%, for sidewalls 20%, for roofs 25%.
Sheathing laid with 2" spaces should have proportionate deductions made, that is, on 1" × 6", figure as if laid solid, then deduct ¼; for 1" × 4" deduct ⅓. Sheathing when matched, such as is used sometimes for sub-floors and side walls and roof sheathing under slate roofs and better known as flooring, will be estimated by figuring the exact surface to be covered, deducting the openings, then adding for 6" stock, which is the kind most always used, 15% for floors, 17% for sidewalls, and 20% for roofs.
If shiplap or matched sheathing is laid diagonally add 5% for waste due to lack of ability to reverse cut.
Siding.— For bevel siding, calculate the exact surface, deduct openings; then add for 6" siding when laid 4½" to the weather, 33%; for the 4" siding add 50%.
Drop Siding.—Drop siding, ceiling and wainscoting are figured just like matched flooring, which is described below.
Flooring.—For square edge, calculate the exact surface to be covered, add for 6" flooring 11% for waste in matching, etc.; for 4" flooring add 20%. It is becoming common practice to specify flooring by actual face measurement after being machined. The following figures are for actual surface measurements.
For matched flooring, calculate the exact surface to be covered, then add 20% for 5¼" flooring, for 3¼" flooring add 25%, for 2¼" add 33%, for 1½ add 40%.
Flooring less than 1" thick, like all other lumber, is estimated as 1" thick.
Shingles.—A bunch of shingles contains the equivalent of 250 shingles of 4" average width. With an exposure of 4½" to the weather a 4" average shingle will cover 18 square inches, making 800 shingles to the square. Waste in doubling the first course and in laying will necessitate an addition of 8% on a plain roof and 12% on hips or on gabled walls. Cost estimates are based upon the M. or 1000.
SHINGLES PER SQUARE