Ancillary Items & Accessories
BW ‘Snaptite’ Purlin Anti-sag Tie & Angle Brace
- The BW ‘Snaptite’ Purlin Anti-sag Tie can be used for many purlin applications.
- The BW ‘Snaptite’ purlin tie prevents the purlin from ‘rotating’ during installation whilst assisting with restraining the bottom flange against wind uplift. The rigidity of the purlin is greatly enhanced once the roof sheeting is installed.
- The BW ‘Snaptite’ ant-sag ties should be fitted when a purlin span is in excess of 4.6m so that the laterally unsupported length does not exceed 3.8m.
- For Z301 & Z341 purlins use ‘sheeting rail’ type angle braces (as diagram above).
- It is recommended the above detail is adhered to if wind loadings are unknown or doubtful.
In some cases ant-sag ties are not required. This situation demands that temporary props/bars are used until the sheeting is fixed, but regardless of wind loading, the absolute maximum spans without permanent ties are:
|Z141, Z151, Z171, Z201||up to 6.1m|
|Z231||up to 7.1m|
|Z261||up to 7.6m|
|Z301, Z341||up to 8.1m|
BW Roof Ties
- 45 x 45 Angle 2mm Galvanised with 2 No. End Brackets.
- 14mm dia. holes required in purlins to take these ties.
- The above Roof Ties should be used for pitches below 4º and purlin spacing exceeding 2.5m.
- These can also be used instead of Eaves Ties.
- Where the roof slope is longer than 18m we would recommend the use of the Roof Ties complete with the diagonal tie system within the roof slope.
BW Diagonal Ties
- For use with the above Roof Ties.
- 5mm diameter Galvanised Wire Rope with 2 No. 40 x 8mm Flat Bar End Brackets.
- 14mm dia. holes required in purlins to take these wires.
BW Apex Ties
- Apex Ties are used to offer rigid restraint on pitched roofs.
- Used in conjunction with anti-sag ties to give perpendicular support to the purlins.
- Apex Ties connect the two uppermost purlins across the ridge and are usually 12mm screwed rod.
- Apex Ties are cranked at the centre point.
- M12 threaded Rod BZP with M12 Nuts & M12 Flat Washers.
- 14mm diameter holes are required in the purlins to take these ties.
BW Cleader Rail
- Available in 2 sizes. Both supplied from stock in 6 metre plain unpunched lengths.
- Small – 45 x 45mm Angle 2mm Galvanised for use where purlin centres are up to 1.8m.
- Large – 100 x 100mm Angle 2mm Galvanised for use where purlin centres are over 1.8m.
- BW Cleader Rail is fixed to the end of the purlins to carry vertical cladding.
- A 6mm gap is recommended for joints in the Cleader Rail.
- A Jointing Cleat to be used where required – not supplied by BW – (size suggested 70 x 60 x 3mm x 50mm long) or simply overlap by approx 28mm.
BW Rafter & Stanchion Stays
- In order to securely fix the purlin to the main steelwork frame, stays are used, fixed as shown using 2 x pre punched 14mm diameter holes.
- Detail consists of: L x 45 x 45 x 2 Galv. Steel
For full details of all BW purlin accessories, please refer to our Purlin brochure or BW detail sheets.
- Purlins – Technical Handbook (5.39 MB)