Walk into any brickyard in South Africa and the bricks are labelled with letters: NFP, NFX, FBS, FBX, FBA. These come from SANS 227, the national standard for burnt clay masonry units, and they tell you what a brick is made for. Choosing the right class saves money where looks don’t matter and avoids problems where durability does. The definitions below are from the Clay Brick Association’s technical guide.
Brick or block?
SANS 227 calls a masonry unit a brick if it is no more than 300 mm long, 130 mm wide and 120 mm high. Anything bigger is a block. The building regulations themselves mostly speak of masonry units and care more about whether a unit is solid or hollow.
Non-facing bricks
NFP, non-facing plastered. Clay bricks suitable for general building work that is to be plastered. These are the everyday bricks for walls that will be plastered and painted, inside and out. Their colour and shape vary, which doesn’t matter under plaster.
NFX, non-facing extra. Clay bricks suitable for use, plastered or unplastered, for general building work below the damp-proof course, in damp conditions or below ground, where durability rather than appearance is what counts. Foundation walls, manholes and walls in permanently damp places are typical uses.
Face bricks
Face bricks are left unplastered, so their appearance matters as much as their durability.
- FBX, face brick extra: selected or made for durability and a high degree of uniformity of size, shape and colour. Use FBX where you want crisp, even brickwork with straight lines and tight tolerances.
- FBS, face brick standard: selected or made for durability and uniformity of size and shape. A good general face brick where slight colour variation is acceptable.
- FBA, face brick aesthetic: selected or made for durability and the look that comes from variation in size, shape or colour. FBA gives a rustic or textured wall, and the bricklayer has to allow for the wider variation.
Engineering units
Any class of brick can also be made as an engineering unit, for structural or load-bearing work, where the maker supplies it to an agreed compressive strength. The class is followed by the letter E and the nominal strength in megapascals. So FBSE21 is a face brick standard with a nominal compressive strength of 21 MPa. When an engineer specifies a brick strength, this is the label to look for.
Clay pavers
The same family includes clay pavers under SANS 1575: PA pavers, chosen for durability and a high degree of uniformity, with length-to-width ratios of about 1:1, 2:1 or 3:1, and PB pavers, chosen for durability and uniformity in size and shape.
Choosing for each part of a house
| Where | Usual choice | Why |
|---|---|---|
| Foundation walls up to the DPC | NFX | Durability in damp ground |
| Walls to be plastered and painted | NFP | Looks don’t matter under plaster |
| Unplastered walls with a neat finish | FBX or FBS | Even size and colour |
| Unplastered walls with a rustic finish | FBA | Character from variation |
| Where the plans give a strength | The class with E and that MPa | Agreed compressive strength |
Practical points
- Check the class on the delivery note matches the order, especially for foundation bricks.
- Order face bricks for the whole job at once, from one batch, and mix bricks from several pallets as you lay to spread any colour variation.
- Mortar matters as much as the brick. Class II mortar is the normal mix for load-bearing walls; see mortar and plaster mixes.
- Face brickwork shows every mistake, so keep joints even and clean off mortar smears while they are fresh.
To count the bricks once you have chosen them, see how many bricks do I need?
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.