General
The fixing of Dimond Purlin Systems is generally carried out by steel fabricators and riggers who are familiar with installation of the Dimond Purlin range.
Handling and Storage
- Correct handling and storage is critical to ensure the Dimond Purlin System is not damaged on site. The following points must be adhered to for maximum product durability and performance over the expected life of the product.
- Site storage must be clear of the ground on dunnage to allow the free movement of air around each bundle. When product is stored on site, it must be kept dry using covers over each product bundle.
- A visual inspection should be carried out, when delivery is taken on site, of all the material supplied to ensure the product is free from damage and the galvanised coating is in good condition.
- Damaged product resulting in a distorted or buckled section shape must not be installed and should be replaced.
- Wear protective gloves when handling the product. Treat all cut edges as sharp.
- Product must always be lifted when moved and not dragged as damage to the galvanised coating will occur.
General Fixing & Workmanship
- Bundle labels should be checked to ensure the correct size and type is used for the designated area.
- Top Notch purlins are placed at premarked centres, and fixed onto the rafter.
- Additional strapping for Top Notch purlins may be required as specified by the design engineer.
- The purlin system must not be subject to or installed on spans that are excessive for the loads imposed during construction, or in the serviceable life of the product. All construction loads must have the design engineer’s approval, prior to loading.
- All connections including those between the purlin system and primary structural framework must be fully fixed and tightened before any loads are applied. Similarly bracing members must be correctly positioned and fastened prior to installation of the roofing or cladding.
- The recommended method for cutting of Top Notch is either by hacksaw or shear cut such as tin snips. If using abrasive disc blade, care must be taken to ensure the swarf doesn’t fall on other products causing rust stains, and the burred cut edge must be cleaned off and primed after cutting.
- Gas cutting of holes, or welding of members, or connections are not recommended, as these may causes an unacceptable loss of member strength capacity. In addition gas cutting or welding will remove the galvanised coating locally around the welded area, reducing the product’s durability.
- Top Notch purlins are not designed for walking on as manufacturing lubricant may still be present on these components. In additional Health and Safety requirements prohibit “walking the purlins”. All on-site Health and Safety requirements must be adhered to.
- Roofing and wall cladding sheets cannot be installed until the roofing contractor is satisfied that the support structure is complete, sound, and correctly aligned. This includes support around penetrations and openings.
- Curved roofs (whether drape/rolled or crimped) require purlin alignment within ±5mm to minimise risk of unacceptable finished appearance.
- Dimond Top Notch purlins are not intended to be used as members to which fall arrest anchor points are attached.
Fixings
Self-drilling screws should be installed as per engineer’s specification, and tightened with mechanical drivers set to a preset torque setting. Avoid overtightening as this may damage the galvanised coating.
| Support Condition | Support Member - Material | Support Member - Grade | Support Member - Min. Thickness (mm) | Purlin Size -60x0.75 and 60x0.95 | Purlin Size -100x0.75 and 100x0.95 | Purlin Size -120x0.75 and 120x0.95 | Purlin Size -150x0.95 | Purlin Size -150x1.15 |
| End | Cold-Formed Steel Steel Timber |
G450 G300 |
1.45 3 37* |
2/12g 2/12g 2/12g |
2/12g 2/12g 2/12g |
2/14g 2/14g 2/14g |
2/14g 2/14g 2/14g |
2/14g 2/14g 2/14g |
| Internal | Cold-Formed Steel Steel Timber |
G450 G300 |
1.45 3 37* |
4/12g 2/12g 2/12g |
6/12g 4/12g 4/12g |
6/14g 4/14g 4/14g |
6/14g 4/14g 4/14g |
8/14g 6/14g 6/14g |
*Minimum screw embedment into timber support.
Notes to table
- Cold-formed option - 2/14g indicates 2 of 14 gauge self-drilling screws fastened into a cold-formed steel (grade G450) support member of 1.45mm minimum thickness. the same rationale applies where 12 gauge screws are required.
- Steel/timber option - 2/12g indicates 2 of 12 gauge self-drilling screws fastened into a Grade 300 hot-rolled steel support member of 3mm minimum thickness, or 2 of 12g x 50mm long Type 17 screws fastened into timber to achieve a minimum embedment length of 37mm. The same rationale applies where 14 gauge screws are required.
- Outward loads shall be adjusted to a lower value if less screws or thinner support members are used.
- A minimum distance of 20mm from the fastener to the end of the Top Notch purlin is required
- Lap end fasteners shall be:
2 screws for the 60 and 100 Top Notch or
4 screws for the 120 and 150 Top Notch
positioned at each end - Lapped Top Notch purlins require additional fixings to be installed in the lapped region.
- When the number of specified fixings above cannot be fixed into the Top Notch and/or Top Notch is being installed in cyclonic regions, an additional hold-down strap should be used (Strap capacity 20kN) - refer drawing A below.
