Structure: Approved Document A

O N L I N E V E R S I O N A1/2 THICKNESS OF WALLS IN CERTAIN SMALL BUILDINGS Diagram 13 Buttressing See para 2C27 2C29 Dimensional criteria for openings and Lateral support by roofs and floors recesses: 2C32 A wall in each storey of a building should The dimensional criteria are given in Diagram 14 extend to the full height of that storey, and have and Table 8. horizontal lateral supports to restrict movement No openings should be provided in walls below of the wall at right angles to its plane. ground floor except for small holes for services 2C33 Floors and roofs should: and ventilation, etc. which should be limited to a maximum area of 0.1m² at not less than a. act to transfer lateral forces from walls to 2m centres. buttressing walls, piers or chimneys; and 2C30 Chases: b. be secured to the supported wall by connections specified in paragraphs 2C34 a. vertical chases should not be deeper than 1/3 and 2C35. of the wall thickness or, in cavity walls, 1/3 of the thickness of the leaf; 2C34 The requirements for lateral restraint of walls at roof and floor levels are given in Table 9 b. horizontal chases should not be deeper than and guidance on satisfying the requirements is 1/6 of the thickness of the leaf of the wall; given in paragraphs 2C35 and 2C36. c. chases should not be so positioned as to 2C35 Walls should be strapped to floors above impair the stability of the wall, particularly ground level, at intervals not exceeding 2m where hollow blocks are used. and as shown in Diagram 15, by tension straps conforming to BS EN 845-1. For corrosion 2C31 Overhangs: resistance purposes, the tension straps should The amount of any projection should not impair be material reference 14 or 16.1 or 16.2 the stability of the wall. (galvanised steel) or other more resistant Continued on page 30 Structure Approved Document A 28 O N L I N E V E R S I O N