Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 65·4.32
Debris collection space for chimneys
A debris collection space must be provided at the base of most chimneys to allow clearance of debris. The space must have a minimum volume of 12 litres and depth of 250 mm below where flue gases enter the flue, unless the chimney is lined, made of flue blocks, or is a factory-made metal chimney.
A debris collection space should be provided at the base of a chimney unless it is lined, constructed of flue blocks, or is a factory-made metal chimney with a flue box. The space should have a volume of not less than 12 litres and a depth of not less than 250 mm below the point where flue gases discharge into the flue. The space should be readily accessible for clearance of debris.
For gas fires of the type illustrated in Diagram 4.1(a) and (b), there should be at least 50 mm clearance between the end of the appliance spigot and any surface.
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