Application of masonry walls for annexes and small single storey buildings

This Part of the Section applies to – (a) an annex to a house; and (b) a small single storey building other than a dwelling. The provisions contained in this Part apply only if the following criteria are met – (a) the floor area of the annex or building is not greater than 36 m2; (b) the walls are solidly constructed in brickwork or blockwork using materials that comply with Tables 4C.6 and 4C.7; (c) where the floor area of the annex or building is greater than 10 m2, the walls have a surface mass of not less than 130 kg/m2. Note: There is no surface mass limitation recommended for floor areas of 10 m2 or less.; (d) access to the roof is solely for the purposes of maintenance and repair; (e) the only lateral loads are wind loads; (f) the maximum length or width of the annex or building is not greater than 9 m; (g) the height of the annex or building is not greater than the lower value derived from Diagram 4C.15 or paragraphs 4C.7 and 4C.8; (h) the roof is braced at rafter level, horizontally at eaves level and at the base of any gable by roof decking, rigid sarking or diagonal timber bracing, as appropriate, in accordance with BS 8103: Part 3; (i) the walls are tied to the roof structure vertically and horizontally in accordance with BS 8103: Part 1 and with horizontal lateral restraint at roof level in accordance with paragraph 4C.43; and (j) the roof structure of an annex is secured to the structure of the main building at both rafter and eaves level.