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Framing Common Roofscapes
Bobtail (Stub Ends)
Bobtail or stub-end trusses are used where the supporting wall position on one or both sides is set in from the normal heel position. (see section 3.9, bearing details). This commonly occurs where recesses occur in the outside wall line of a building or where walls are built up to tile level to provide a firebreak compartment within the building. The horizontal 'A' dimension (figure 32),  known as the cut-back, is therefore conveniently used to specify the shape for duo-pitch trusses, while double bobtailed trusses and bobtailed mono-pitched trusses are often more conveniently specified by a vertical 'A' dimension, known as the End Height.
Figure 33 shows typical end details when the outer leaf is of masonry. Arrangement 33b is best confined to timber frame construction as separate columns of masonry between trusses could be unstable. There should be sufficient depth of masonry on figure 33a to anchor the roof down against wind uplift. If the end verticals are to be tile clad, one of the arrangements in figures 33c or d is suitable. In figure 33c a specially wide timber is used as the end vertical
of the trusses so that the tile battens clear the outer leaf of the wall; the inside of the end vertical member of the truss must not be located to the right of the centre-line of the wallplate. In some cases this arrangement is impractical owing to the large width required for the end vertical. In many cases the diagonal in the cantilevered part (figure 33d) can be omitted if there is little load from the cladding.
Bobtailed trusses must never be formed through onsite modifications of standard truss types with which they align, following the basic rule that a trussed rafter should never be cut, notched, drilled or otherwise modified without first checking with the Trussed Rafter Designer.