C3: Fixings

3.1 Screws and nails

Screws shall comply with BS 1210 and nails with I.S. 105 or BS 1202. In every case the size and material of screws and nails shall be as specified or and appropriate to the nature of the fixing and of the materials involved. Screws, nails or metal fastenings in hazardous locations or conditions must be non-ferrous, e.g. austenitic stainless steel, silicone bronze, no other screws or nails are permitted. The fixing of external cladding, joinery or window beads with non-stainless steel or silicon bronze screws, nails or fixing pins shall not be allowed.

3.2 Bolts

All bolts, nuts and washers described on drawings as galvanised shall be hot-dipped galvanised, and those of stainless steel as austenitic stainless steel. Bolt holes shall be drilled to diameters as close as possible to the nominal diameter of the bolt and in no case more than 2.0 mm larger than the bolt diameter. A minimum of one complete thread shall protrude from the nut. Care shall be taken to avoid placing a bolt in any end split. The washer size shall comply with BS 5268 Part 2. Generally the smooth load bearing element of the shank shall be in full contact with the jointed members across the full width of the joint.

All metals used in a joint must be compatible with each other to avoid electrical corrosion.

3.3 Connectors

All toothed-plate connectors are to comply with BS 1579. All toothed-plate connectors together with bolts and washers are to be hot-dipped galvanised to EN 1461 or austenitic stainless steel or/and as specified. The connectors shall be fitted and embedded as described in BS 5268 Part 2. The washer size and thickness shall comply with BS 5268-2 and/or BS 1579.

3.4 Brackets, joist hangers, plates

All proprietary brackets, joist hangers, plates and the like must be approved by the architect or the engineer before any assembly commences. All brackets, joist hangers plates, etc. must be hot-dipped galvanised using double-dipped process to EN 1461 or stainless steel as described in drawings.

3.5 Tightening of bolts or connectors

Care must be taken to avoid the over-tightening of bolts in bolted or connector joints such that no crushing of the wood occurs under the washer.

3.6 Adhesives

Adhesive shall be Adhesive Type I to EN 301. PVA glues shall NOT be permitted. The mixing of the adhesive elements shall be carried out in clean containers; mix proportions, method of mixing, air temperature, method of application, rate of spreading, method of clamping including any pressure requirements, curing etc., shall be strictly in accordance with the adhesive manufacturer's instructions.

Adhesive spreading shall be carried out within the manufacturer's stated `open storage' time and any adjustments in alignment or clamping after the two mating surfaces have been brought into contact, shall be carried out within the manufac-turer's stated `closed storage' time.

At the time of adhesive application the moisture content shall comply with the man-ufacturer's requirements.

The surfaces of the timber to be fixed with adhesive shall be machined and the application of adhesive carried out within 48 hours of machining. Care shall be taken that the adhesive to be used is compatible with any treatment applied to the timber (e.g. a preservative or fire retardant).

Where any adhesive joints occur on exposed areas of timber, the exposed areas shall be lightly planed after application of adhesive such that all adhesive which has been `squeezed out' of the joint is removed to the satisfaction of the architect.