The answer people quote is 60 bricks a square metre in the UK. It comes from the size of a brick plus one mortar joint each way.
The UK brick
A UK brick is 215 mm long and 65 mm high on the face. With a 10 mm joint each way it takes up 225 × 75 mm of wall, which is 0.016875 m². One divided by that is 59.26 bricks a square metre for one skin. Travis Perkins quotes about 60.
A double skin wall, two bricks thick, is twice that: 118.5 a square metre.
The Australian brick
An Australian standard brick is 230 mm long and 76 mm high. With 10 mm joints it takes 240 × 86 mm, which is 48.45 bricks a square metre. Austral and Midland Brick list 48.5.
| Wall | Per m² | Bricks | Cement | Sand |
|---|---|---|---|---|
| UK single skin | 59.26 | 593 | 56 kg, 3 × 25 kg | 312 kg |
| UK double skin | 118.52 | 1186 | 144 kg, 6 × 25 kg | 802 kg |
| AU single skin | 48.45 | 485 | 54 kg, 3 × 20 kg | 299 kg |
| AU double skin | 96.90 | 969 | 139 kg, 7 × 20 kg | 775 kg |
Mortar
Mortar fills the space the bricks do not. For solid bricks it is the wall's volume minus the bricks' volume. Dry sand and cement shrink when mixed with water, so the dry mix is taken as 1.33 times the wet volume.
At one part cement to five parts sand, cement is a sixth of the dry mix at 1440 kg/m³, and sand is the rest at 1600 kg/m³. These are labelled assumptions, not a specification.
Frogged and cored bricks take more mortar than solid ones, so treat the cement count as a minimum. Lime and plasticiser are not counted.
A worked garden wall
A UK single skin wall 5 m long and 1.2 m high is 6 m². That is 355.6 bricks net, and 374 with 5% waste for cuts and breakages. The mortar is about 0.11 m³: 35 kg of cement, two 25 kg bags, and about 197 kg of sand.
Walls that hold back soil, carry a load or are taller than a low garden wall need a design. This is a shopping count only.
Figures are estimates for a shopping list. Check the pack or datasheet before you buy.