Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 44·3.17
Masonry and flue block chimneys
Masonry and flue block chimneys must be built according to specified paragraphs, with minimum thickness and distance to combustibles determined by manufacturer testing to relevant standards.
Masonry chimneys should be built in accordance with paragraphs 2.21 and 2.22. Flue block chimneys should be built in accordance with paragraphs 2.23 and 2.24. The minimum chimney thickness and distance to combustibles (xx mm) should be no less than the manufacturer's product declaration (Gxx) based on testing to BS EN 1858 (concrete flue blocks) or BS EN 1806 (clay/ceramic flue blocks). Other masonry chimney products should exceed the minimum thickness indicated in Diagram 2.4.
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