- Selecting bricks
When ordering or specifying clay bricks, ensure the following points are discussed and made known to the suppliers:
- Expected sizes. Not all bricks are manufactured to the standard imperial size of 222mm long x 106mm wide x 73mm high
- The required application e.g. type of building, finish etc.
- The degree of exposure to weather conditions, closeness to the seas etc.
- The track record of the preferred brick in the area where you are building
- An undertaking or warranty from the brick supplier that the bricks delivered will be fit for purpose
- Colour expectations in the case of face bricks or exposed brick areas
- The acceptable levels of breakage during delivery to site
- The the brick manufacturer registered with the Clay Brick Association of SA.
To avoid colour banding it is highly recommended that face bricks are taken from a number of different packs and carefully blended during building operations.
Properties that require consideration when buying or specifying clay brick are:
- Compressive strength (varies from 7MPa to 50MPa)
- Water absorption (face brick up to 10%, NFP up to 16%)
- Modulus of rupture - strength in bending
- Moisture expansion - important when detailing long walls
- Initial rate of absorption: This affects the development of bond between the mortar and the brick. Bricks with high rates of absorption (often lower quality) may require pre-wetting well before laying to prevent absorbing excessive water from the mortar mix. Trial and error experiments when bricks arrive on site will determine the need to pre-wet bricks.