Trussed rafters: Strapping

The Buildings Regulations Approved Document A recommends the use of straps in new roofs, so that the gable walls are tied back to the roof structure at intervals of not more than 2m. The strapping is to prevent movement of the gable walls under wind load. This strapping is required at rafter level and, in steep roofs, at ceiling-joist level to prevent the middle of the wall from buckling or bulging.