Cracking in external walls

Severe rain penetration may occur through cracks in masonry external walls caused by thermal movement or by subsidence. The possibility of this occurring should be taken into account when designing a building. Detailed guidance is given in – (a) BRE Building elements: walls, windows and doors – performance, diagnosis, maintenance, repair and avoidance of defects; (b) BRE Report 292 Cracking in buildings; and (c) guidance on choice of materials is given in BS 5628-3.