This section is from the book "A Treatise On Architecture And Building Construction Vol2: Masonry. Carpentry. Joinery", by The Colliery Engineer Co. Also available from Amazon: A Treatise On Architecture And Building Construction.
281. In making a contract for brickwork, when the payments depend on the number of brick and other materials in the wall, it should be distinctly stated, in order to avoid disputes, how the work is to be measured and whether or not deductions are to be made for the openings and stonework.
282. The usual method of measuring is by the thousand brick as laid in the wall. Most mason contractors, in estimating on the cost of brickwork, take the entire superficial area of the wall in square feet, measuring it on the outside of the wall, so that the angles are taken twice. This is done to allow for the extra labor in laying up the angles. The brick are then computed as laying 7 1/2 brick to the square foot to a 4 or 4 1/2 inch wall, 15 for an 8 or 9 inch wall, 22 1/2 for a 12-inch wall, 30 for a 16-inch wall, and so on, adding 7 1/2 brick per square foot for every additional thickness of 4-inch wall.
In Figuring for the pressed brick, when the walls are faced with them, the whole superficial area of the wall is taken, and the 4 and 4 1/2 inch pressed brick facing is estimated at 7 1/2 brick to the superficial foot, to give the number of pressed brick in the wall. Deductions are made for all openings, and when the reveal of a window is more than 4 inches, the additional depth is Figured and added to the whole number of pressed brick.
The Figures above given apply to the Eastern and New England states. In the West and South the bricks are larger, and give from one-quarter to one-third less per square foot in the wall than in the East, and the price is regulated accordingly. In some parts of the "West and South two measurements are used. The first, or kiln count, represents the actual number of brick purchased and used, while the second, or wall measure, designates the number of brick in the wall, estimating 22 1/2 brick to every superficial foot of 12-inch wall.
283. Among some builders the custom prevails to reduce all brickwork to cubic feet and estimate in that way. As for example, a wall 24 feet long, 12 feet high, and 20 inches thick would contain 24 ft. X12 ft. X1 ft. 8 in. = 480 cu. ft, at 22 1/2 brick per cubic foot = 10,800 brick.
284. Unless openings are very wide and numerous, it is not customary to deduct them in estimating for common brickwork. Hollow walls and ordinary chimneys with 8" X 8" or 8"X12" flues are usually measured as though they were solid brickwork.
When the contractor who has the contract for the brickwork sets the stone caps, sills, quoins, belt courses, etc., no deduction is usually made for the pressed brick that would take the place of the stonework. If, however, the stonework is furnished and set by another contractor, an allowance is often made for the face brick displaced by the stone.