Brick and mortar are estimated by the wall-area method in BIA Technical Note 10, Table 4.
The method
Net area = gross wall area − openings
Material = net area × rate
Rates are per 100 sq ft, so divide by 100 (675 per 100 sq ft is 6.75 per sq ft).
Brick per 100 sq ft
- Modular (nominal 4 × 2-2/3 × 8 in): 675.
- Standard non-modular (3-5/8 × 2-1/4 × 8 in): 655.
800 sq ft of standard brick is 800 × 655 ÷ 100 = 5240; using 6.75 gives 5400, the modular figure. 616 and 700 are not table values.
Deduct the openings
A modular wall 40 ft by 10 ft with two 3 × 5 ft windows and one 3 × 7 ft door:
- Gross: 40 × 10 = 400 sq ft.
- Openings: 2 × (3 × 5) + 3 × 7 = 51 sq ft.
- Net: 400 − 51 = 349 sq ft.
- Brick: 349 × 6.75 = 2355.75.
- With 5% waste: 2355.75 × 1.05 = 2473.5, rounded up to 2474.
2356 omits waste, 2700 skips the openings is gross with no waste, and 2835 is gross plus waste.
Mortar for modular brick
- 3/8 in joints: 5.5 cu ft per 100 sq ft, or 8.1 cu ft per 1000 brick.
- 1/2 in joints: 6.9 cu ft per 100 sq ft, or 10.3 cu ft per 1000 brick.
By area: 600 sq ft at 3/8 in is 600 × 5.5 ÷ 100 = 33.0 cu ft. By count: 4000 brick at 3/8 in is 4 × 8.1 = 32.4 cu ft.
Match the rate to the unit. Using 8.1 on area gives 48.6; using 5.5 or 6.9 on a brick count gives 22.0 or 27.6. Match the joint size too: the 1/2 in rates give 41.4 and 41.2 here.
Net means no waste
Table quantities exclude waste. When a question says "before waste", stop at the net figure: adding 20% to 33.0 gives 39.6, and adding 5% to 5240 gives 5502.