BS 5268-7.7:1990 PDF

BS 5268-7.7:1990 recommends a calculation basis for the permissible clear span of purlins supporting sheeting or decking in pitched roof construction. The recommendations apply to purlins formed from solid timber and supported by external or internal walls. The major axis of the purlin is perpendicular to the roof slope; other orientations of the purlin are not covered by this standard. The uniform and concentrated loads of BS 6399-1 are considered. Provision is made for a uniformly distributed snow load derived from BS 6399-3. BS 5268-7.7:1990 is applicable to the species, stress grades or strength classes of timber given in BS 5268-2.