These are used to carry trusses or joists at masonry load bearing or fire break walls. Careful consideration must always be given to the method of
support. We would recommend that advice is obtained from the responsible Building Designer or Structural Engineer since in a number of cases special hangers may have to be manufactured. The Building Designer may also specify high density brick courses above and below the hangers to avoid
crushing of blocks. The bearing length for these joist hangers is approximately 90mm. (See figures 55 and 56).
Heavy-duty girder to girder truss shows
These are designed to support a secondary girder off the main girder ensuring that the loads are transferred efficiently. The shoe is usually fixed to the main girder (A) by means of bolts as specified by the manufacturer with washers under the bolt heads and nuts. The bearing length for these shoes is approximately 120mm. (See figure 57). NB. Refer to manufacturers instructions for the correct application and procedure.
Girder truss shoe and long legged hangers
Girder truss shows are used to fix single trusses to compound girders or for other truss to truss connections. The bearing length is approximately 65mm.
The shoe or hanger must have side flanges of a size which suits the depth of the girder chord to which it is fixed. Some joist hangers are suitable only for timber or timber to truss connections not for truss to truss connections, always use the appropriate hanger. (See figure 58).
Metal fixings used in timber roof structures should have safe working loads which can be substantiated by freely available reports in accordance with
BS6178 and TRADA recommendations. They should always have a manufacturer's mark and show the certified safe working load.
It is strongly recommended that timber to timber fixings and timber to brick fixings should be supplied by the Roof Truss Fabricator, and delivered to site with the trusses.