- Bracing omitted for clarity
- Returns on straps should be fastened to uncut blocks
- Third truss omitted for clarity
Strapping Gables to rafters
Straps provide most of the lateral stability to the gable wall and are nearly always required. They must engage a full block on a gable, and will need to be fitted to the underside of the rafter members. Nail each strap to at least three rafters and to the timber noggings, which are needed between the rafters (as shown right).
Straps can be fixed before the gable is built, but great care is needed to ensure that downturns are in line and match with coursing. Straps can be built into the masonry in their correct positions and temporarily tied to the rafters; allowing noggings and packing to be added later. Nailing a strap (or even screwing it) into position while the masonry is green is difficult to do without disturbing and weakening the blockwork.
How to fix rafter straps
- Engage at least three rafters with each strap
- Straps of 5 x 30mm galvanised steel
- Use corrosion resistant nails (3.35 x 65 mm)
- Pack between end rafter and wall
- Nail noggings securely to the rafters
- Straps to have at least 100mm downturn tight against a full block on the gable