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Roof type 2: pitched roofs [Note 1] |
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A. Pitched roof structure of timber or metal framed construction. |
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External weatherproof covering of slates or tiles on under stating felt with or without boards or battens. |
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Insulation laid on a level ceiling with a ventilated space between the insulation and the roof structure. |
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B. Pitched roof structure as A. above. |
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External weatherproof covering as A. above. |
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Insulation and vapour control layer laid on a sloping ceiling, with a ventilated air space 50mm in depth between the insulation and the boards of the pitched roof covering. |
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C. Pitched roof structure as A. above with a decking of low permeability insulation fitted to and between the roof framing. |
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External weatherproof covering of slates or tiles, with tiling battens and counter battens (located over roof framing), and a breather membrane laid on the insulation decking; with a sloping ceiling. |
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D Pitched roof structure as A. above. |
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External weatherproof covering of metal or fibre cement sheet sandwich construction laid on purlins; with insulation sandwiched between the external and soffit sheeting; and with or without a ceiling. [Note 1] |
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Note:
1. Roof type 2D. is not suitable for sheet metal coverings that require joints to allow for thermal movement. See also ‘General’ f. of the provisions deemed to satisfy G3.1.
(G4.1) The requirements of G4.1 will be met where the walls, roofs and floors are assessed and/or constructed in accordance with Appendix D and Clauses 9.1 to 9.5.5.2 of BS5250: 1989.
(G4.2) The requirements of G4.2 will be met where openings and junctions in or between the specified elements are constructed in accordance with Clauses 9.6.1 to 9.6.3 of BS5250: 1989 to a thermal transmittance (U-value) which does not exceed 1.2 W/m2K at any point.
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