External wall material performance for relevant buildings

The provisions of Regulation 23 apply in addition to the requirements of regulation 36. Therefore for buildings described in Regulation 23(4), the potential impact of any products incorporated into or onto the external walls should be carefully considered with regard to their number, size, orientation and position. Particular attention is drawn to the following points – (a) membranes used as part of the external wall construction above ground level should achieve a minimum of European Class B-s3, d0; (b) internal linings should comply with the guidance provided in Section 3 of this booklet. (c) any part of a roof should achieve the minimum performance as detailed in the relevant paragraphs of Section 5 of this booklet; (d) as per regulation 23(3), window and door frames and associated glass (including laminated glass) are exempted from regulation 23(2). Window spandrel panels and infill panels must comply with regulation 23(2); (e) thermal breaks are small elements used as part of the external wall construction to restrict thermal bridging. There is no minimum performance for these materials. However, they should not span two compartments and should be limited in size to the minimum required to restrict the thermal bridging (the principal insulation layer is not to be regarded as a thermal break); (f) regulation 23(2) applies to specified attachments. Shop front signs and similar attachments are not covered by the requirements of regulation 23(2), although attention is drawn to paragraph (g) below; and (g) while regulation 23(2) applies to materials which become part of an external wall or specified attachment, consideration should be given to other attachments to the wall which could impact on the risk of fire spread over the wall.