Don’t leave a gap when using Joist Hangers
Joist hangers and truss boots are widely used in both residential and commercial buildings. It’s important that these are installed correctly. Roof trusses or floor joists, should fit snugly into the brackets and sit hard against the girder truss or bearer. We recommend that the gap between the supporting element and the supporting element, not exceed 2mm.
A large gap will allow rotation between these elements and will result in a reduced bearing area. Joist hangers and truss boots have been designed to give adequate end distances for all nail, screw or bolt fixings, but leaving a gap will result in an insufficient end distance, and reduce their capacity.
Not only is the gap between the two members important, but also the gap between the member and bracket bottom plate. If the truss or joist is not sitting on the truss boot or joist hanger, the fixings (i.e. Nails, screws or bolts) will be taking the structural load and will eventually fail.
We recommend that no gap is allowed on installation to avoid a serious failure, such as decking failure or roof collapsing, at a later date.