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 12 Openings in a buttressing wall See para 2C26 a. half the thickness required by this section for to the wall. Piers should have a minimum an external or separating wall of similar height width of 190mm (see Diagram 13); and length less 5mm; or b. the sectional area on plan of chimneys b. 75mm if the wall forms part of a dwelling (excluding openings for fireplaces and flues) house and does not exceed 6m in total height should be not less than the area required and 10m in length; and for a pier in the same wall, and the overall thickness should not be less than twice the c. 90mm in other cases. required thickness of the supported wall The length of the buttressing wall should (see Diagram 13). be at least 1/6 of the overall height of the supported wall and be bonded or securely tied Openings, recesses, overhangs to the supporting wall and at the other end to a and chases buttressing wall, pier or chimney. The size of any opening in the buttressing wall 2C28 General: should be restricted as shown in Diagram 12. The number, size and position of openings and recesses should not impair the stability of a wall 2C27 Design criteria for piers and chimneys or the lateral restraint afforded by a buttressing providing restraint: wall to a supported wall. Construction over a. piers should measure at least 3 times the openings and recesses should be adequately thickness of the supported wall and chimneys supported. twice the thickness, measured at right angles Approved Document A Structure O N L I N E V E R S I O N 27