Structure: Approved Document A

O N L I N E V E R S I O N A1/2 Section 2A: Basic requirements for stability 2A1 This section must be used in conjunction with sections 2B and 2C and its principles relate to all forms of low-rise residential buildings. 2A2 Adequate provision shall be made to ensure that the building is stable under the likely imposed and wind loading conditions. This will commonly necessitate meeting the following requirements: a. That the overall size and proportioning of the building are limited in accordance with the specific guidance for each form of construction. b. That a suitable layout of walls (both internal and external) forming a robust 3 dimensional box structure in plan is constructed with restriction on the maximum size of cells measured in accordance with the specific guidance for each form of construction. c. That the internal and external walls are adequately connected either by masonry bonding or by using mechanical connections. d. That the intermediate floors and roof are of such construction and interconnection with the walls that they provide local support to the walls and also act as horizontal diaphragms capable of transferring the wind forces to buttressing elements of the building. Note: A traditional cut timber roof (i.e. using rafters, purlins and ceiling joists) generally has sufficient built in resistance to instability and wind forces (e.g. from hipped ends, tiling battens, rigid sarking or the like). However, the need for diagonal rafter bracing equivalent to that recommended in BS EN 1995-1-1:2004 with its UK National Annex and additional guidance given in BSI Published Document PD 6693-1:2012 and BS 8103-3:2009 for trussed rafter roofs should be considered, especially for single-hipped and non-hipped roofs of greater than 40° pitch to detached houses. Approved Document A Structure O N L I N E V E R S I O N 11