Fireplaces, chimneys and flues


Masonry shall be capable of supporting intended loads and have appropriate resistance to the adverse effects of frost and sulfates.

Masonry, including bricks, blocks, stone for masonry and reconstructed stone, should:

  • be in accordance with BS 6461 or BS EN 15287-1 and BS EN 771
  • where clay bricks are used in external chimney stacks, be of durability rating F2,S1 (as described in BS EN 771) or protected by a projecting capping
  • where blocks are used, have a minimum block density of 1500kg/m3 unless designed by an engineer in accordance with Technical Requirement R5.

In Scotland:

  • frost-resistant bricks should be used for all external facing brickwork
  • where 100mm blocks are used for chimney construction, they should have a minimum density of 1500kg/m3.