Outline
It is the responsibility of the timber frame manufacturer to provide a comprehensive site fixing schedule to accompany a full, comprehensive set of construction drawings specific to the dwelling under construction. This section highlights typical fixing details that should make up the basis of the site fixing schedule supplied by the timber frame manufacturer.
Information in this section is not exhaustive and the preference should always be given to the timber frame manufacturer's preference. If any item within the site fixing schedule is not available it is important the timber frame manufacturer is contacted to find a suitable alternative.
Common devices
The most common fixing in timber frame construction is a typical framing nail 3.1 dia. x 75/90 mm long. Although this is the most common type of fixing used, the site fixing schedule may specify other diameters and lengths of nails. When this occurs the specification of the fixing outlined in the site fixing schedule must be adhered to strictly.
For items such as breather membranes, flexible cavity barriers, etc. staples are the most common device used to fix these materials. All staples should be austenitic steel; other materials are allowed but only when specified.
Plasterboard, supplied fixing, and clips
Plasterboard fixings require a solid base for fixing to. In typical construction, this base is provided by the timber frame studwork with a minimum of 20 mm bearing for the fixing. The plasterboard support and fixing overall length will be determined by whether the wall or ceiling plasterboard is installed first. Fixings supplied with products such as wall ties, holding down straps, joist hanger, etc. should be used with the product they have been supplied for.
4 mm diameter stainless steel masonry nails should be used to fix the sole plate to the substructure walls. The nails should provide a minimum of 50 mm penetration into the wall positioned at a maximum of 400 mm centres. Stainless steel anchor clips may also be used as a point for the nails to be fixed to; anchor clips should be located at 1.2 m centres.
To prevent any damage to the DPC or DPM, the clips should be attached to the outer surface of the inner leaf of the rising wall. The clip should be of sufficient size so that it can provide adequate fixing to the substructure rising wall without damaging any of the blockwork.
Sole plates
Unless otherwise specified by the timber frame manufacturer, anchor straps should be provided at all corners, on each side of openings, and intermittently at 1.6 m max. centres for studs, at 400 mm centres, and 1.8 m max. centres for studs at 600 centres.
Notes:
1. Typical nail specification, unless otherwise stated, is either min. 3.1 mm dia. x 75 mm long gas nail gun or min. 4 mm dia. x 100 mm long hand-driven nail. Nails should be corrosion resistant, i.e. galvanised or stainless steel.
2. Care should be taken to ensure that nails are driven into the timber and not fresh air. In addition, nails should not be fixed too close to the edge of the timber which may cause splitting and render the nail ineffective.
3. Bridging pieces between l-Joists omitted for clarity. Bridging pieces provide another element within the floor structure to which wall panels can be fixed.
Wall Ties
Wall ties require the following spacings:
Vertically – 450 mm and 225 mm at opes.
Horizontally -- 405 mm or 605 mm depending on the spacing of stud centres.
Vertically – 225 mm, staggered at movement joints.
50 mm minimum embedment into the masonry leaf.
Wall ties should be fixed into the stud framework by use of nails fixed through the sheathing material at the points identified vertically on the breather membrane.
