Hip End Roofs

The construction of trussed rafter hip end roofs varies from one truss system to another. Precise construction details are therefore given in Chapter 7 under each plate manufacturer's heading.

On roofs less than 5 m span almost traditional hip construction may be used, as detailed in Chapter 3. In excess of this span most systems use prefabricated hip trusses with, in some cases, only the extreme lower corners of the hip being of site cut and fitted construction. More details of the variation between trussed rafter manufacturers' hip construction are given in Chapter 7.

Rafter diagonal bracing is not generally required in a hip roof, the hip itself being a rigid diagonal structure. Longitudinal binders G must be continued from the main roof into the hip construction, plus additional binders H fixed flat on top of the hip trusses' top chords. Diagonal K should be installed (see Fig. 6.5).

Most trussed rafter hip constructions involve a compound girder assembled from two, three or in some cases four individual trussed rafters. The nailing together of these individual components to form a girder is critical, and should be carried out by the trussed rafter manufacturer at works. If girders are not nailed by the manufacturer then a nailing and bolting detail must be provided by the roof designer. When fastened together on site, bolts must be used for the bottom chord members, in positions marked by the truss manufacturer. In all cases the nails and bolts must be positioned strictly in accordance with the manufacturer's instructions. See a typical nailing and bolting pattern given in Fig. 6.10a. The setting out of the girder and intermediate trussed rafters is also critical and dimensions given on drawings must be carefully followed.

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