Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 63·4.24
Flue block chimneys - materials and construction
Flue block chimneys must be constructed from factory-made flue block systems, either solid fuel systems or modular systems with specific components meeting BS EN 1858 or BS EN 1806 standards.
A flue block chimney should be constructed from either –
(a) a factory-made flue block system primarily designed for solid fuel, as described in paragraphs 2.23 and 2.24; or
(b) a factory-made flue block system comprising of straight blocks, recess units, lintel blocks, offset blocks, transfer blocks and jointing materials complying with –
(i) BS EN 1858 for concrete flue blocks of at least class D2; or
(ii) BS EN 1806 for clay/ceramic flue blocks, with a performance class of at least FB4 N2.
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