Party walls should be stopped 25mm below the tops of rafters. During construction layers of noncombustible compressible fill such as 50mm mineral wool should be pressed onto the locations shown to provide a fire stop as figure 106.
Continuity across party walls
If the tiling battens are required to be discontinued over a party wall, then lateral restraint must be provided in addition to that required to transfer
longitudinal bracing forces.
This should consist of straps adequately protected against corrosion. These straps should be spaced at not more than 1.5m centres and be fixed to two rafter members and noggins on each side of the party wall by 3.35mm diameter nails with a minimum penetration into the timber of 32mm.
Fixing over flat-top girder
Where hipboards pass over and are supported on flat top girder trusses, the hipboard must be notched in order to achieve the correct height for the hipboard and to provide horizontal bearing. The flying rafter of the truss may need to be trimmed but in no circumstances should the flat chord or the rafter below the joint be cut. In most cases the hipboard is supplied in two parts which can be joined over the flat top truss. One method of providing the necessary fixing is illustrated in figure 108.