Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 29·2.37
Factory-made metal chimney distance from combustible materials
Factory-made metal chimneys must maintain a safe distance from combustible materials as defined in BS EN 1856:1, with a minimum separation of 25 mm, and protective guards may be required in cupboards, storage spaces or roof spaces.
A factory-made metal chimney should be kept a safe distance away from any combustible material. For a chimney designated to BS EN 1856: 1 the following provisions are a reasonable method of achieving this –
(a) locate the chimney not less than the distance "XX" from the combustible material, where "XX" is the dimension defined in BS EN 1856: 1 as shown in Diagram 2.5; or
(b) where the chimney passes through a cupboard, storage space or roof space, a suitable guard should be provided no closer to the outer wall of the chimney than "XX" as given above. See Diagram 2.5.
In no circumstances should the separation "XX" between the chimney and the combustible material, or suitable guard be less than 25 mm.
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