Civil Engineering Reference
In-Depth Information
3 limits deflection to 12 mm for roofs up to 12 m span. Consequently at maximum deflec-
tion of the trussed rafter roof there is still a 12 mm gap between the top of the rafter and
the top of the brickwork. This gap must be filled with compressible yet non-combustible
material (usually mineral wool), the tile battens themselves being the only timber item to
pass from one building to the other. The detail described avoids the problem of hogging
and its unsightly effect on the roofs of terraced houses. Figure 7.16 illustrates the correct
detail.
Fig. 7.16
Fire stop at compartment wall.
Gable Wall Restraint
The question of pressure on one end of the gable end of a house and suction on the other
end was discussed in Chapter 5. Figure 7.17 illustrates this effect.
Above the wall plate the gable end is of course free standing brickwork and on steep
pitched roofs this area of gable brickwork can be quite large, and the resulting
