Concrete Block Strength

The following rules of thumb for selecting block strength to storey height is taken from Approved Document A of the Building Regulations England & Wales:

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Notes:

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1. If HS is not greater than 2.7m, the compressive strength of bricks or blocks should be used as indicated in the ‘key’ table above.
2. If HS is greater than 2.7m, the compressive strength of bricks or blocks used in the wall should be at least Condition B, or as indicated by the key, whichever is the greater.
3. If the external wall is solid construction, the masonry units should have a compressive strength of at least that shown for the internal leaf of a cavity wall in the same position.
4. The guidance given in the diagram for walls for 2 & 3 storey buildings should only be used to determine the compressive strength of masonry units where the roof construction is of timber.
5. The 'Conditions' table indicates the minimum block strength required. That is, where a 2.9N/mm2 block is indicated, a 3.6N/mm2, 4.2N/mm2 etc block would be perfectly suitable.

(of selected aggregate block types, 440mm long x 215mm high)