Restraint of walls & Joists
Walls should be adequately restrained at floors, ceilings and verges in accordance with building regulations. Restraint can be provided by;
– Restraint type joist hangers
– Lateral restraint straps
Restraint type hangers;
– The hanger is bedded directly on the masonry and there is no gap between the hanger back-plate and the face of the masonry.
– At least 450mm of masonry is provided above the hanger.
– Hangers are spaced at centres of floor joists included in the design.
– The hanger is suitable for the loadings and masonry strength.
– Do not use hangers marked for use with a particular block strength on blocks of lower strength e.g don’t use 3.5N/mm2 hangers on 2.8N/mm2 blocks.
The HSE has to deal al with the failure of joist hangers where they haven’t been installed correctly and floors collapse. A worker died and 2 others were badly injured at a construction site in Putney, when a temporary platform collapsed. An investigation by the HSE found that similar platforms had been constructed on other floors throughout the site, using timber joists supported by unsuitable joist hangers with plywood fixed on top. The platforms, which were part of the ‘temporary works’ were neither built to an agreed safe design, nor was the quality of the build checked by those in control of the site, even though they were crucial to the safety of workers on upper floors.