Counting bricks is simple once you know two things: how many bricks go into a square metre of wall, and how much wall you really have. This guide gives the South African numbers for standard bricks, maxi bricks and concrete blocks, then works through a room from start to finish.
Bricks per square metre
A standard South African brick is 222 × 106 × 73 mm. With 10 mm mortar joints it takes up 232 × 83 mm of wall face, which gives:
| Unit | Wall | Per m² |
|---|---|---|
| Standard brick, 222 × 106 × 73 mm | Single brick (about 110 mm) | 52 |
| Standard brick | Double brick (about 230 mm) | 104 |
| Maxi brick, 290 × 140 × 90 mm | Single (140 mm) | about 33 |
| Maxi brick, 290 × 140 × 110 mm | Single (140 mm) | about 27 |
| Concrete block M140, 390 × 140 × 190 mm | 140 mm wall | 12.5 |
| Concrete block M190, 390 × 190 × 190 mm | 190 mm wall | 12.5 |
The maxi brick figures are worked out from the face size plus 10 mm joints; Killarney Brick & Block quotes 27 per m² for its 110 mm-high maxi. Check your supplier’s figure for the exact brick you buy.
Measuring the walls
Work wall by wall, or room by room:
- Measure each wall’s length along its centre line, so corners aren’t counted twice.
- Multiply by the height from the top of the foundation walls or slab to the underside of the roof or wall plate.
- Take off doors and windows: width × height of each opening.
- Gables are triangles: half the width × the height from the wall plate to the apex.
Lintels, sills and the brickforce in the joints don’t change the count much, but piers, chimneys and thickened sections do, so add them separately.
Waste
Some bricks break in delivery and handling, and some are cut. Allow about 5% on ordinary brickwork, and more if the wall has many corners, openings or decorative work, or if the bricks are face bricks that must be chosen for colour.
Mortar
The Concrete Society of Southern Africa gives mortar per 1,000 bricks. For Class II mortar, the normal mix for load-bearing walls, that is 150 kg of common cement (three 50 kg bags) and 0.6 m³ of building sand. Class I, the stronger mix, takes 200 kg of cement and 0.55 m³ of sand. Bigger units need more mortar per unit but fewer units, and the mortar calculator scales the figures for maxi bricks and blocks. See mortar and plaster mixes.
Worked example: one room
A room is 4 × 3.5 m on the centre line of single-brick walls, 2.6 m high, with a door and a window that together make 3 m² of openings.
- Wall area = 2 × (4 + 3.5) × 2.6 − 3 = 36 m².
- Bricks = 36 × 52 = 1,872, or 1,966 with 5% for breakage.
- Class II mortar = 1.966 × 150 kg = 295 kg of cement, which is 6 bags, and 1.966 × 0.6 = 1.18 m³ of building sand, so order 1½ cubes.
In double brick the same room takes twice the bricks and mortar. The room bricks and mortar calculator does this for any room, and the brick calculator and block calculator handle single walls.
Ordering tips
- Order face bricks from one batch so the colour matches across the job.
- Check the class of brick suits the work: see NFP, NFX, FBS, FBX: choosing the right brick.
- Have the bricks stacked close to where they will be used, on firm, level ground.
- Order sand by the cube or half cube, and keep building sand separate from concrete and plaster sand.
This guide is general information for estimating. It is not engineering, legal or tax advice. Check SANS 10400 (the National Building Regulations) and your local municipality’s building control officer for your project.