Metal Tek Screw With XGRiP

Roofing tek screws with XGRiP

These are Hobson DRiLLX metal point self-drilling (tek) screws for fixing metal roof sheeting through the crest into steel. Hobson lists the #12-14 for metal to metal fixing, fastening roofing panels to steel purlins and battens and crest fixing roofing sheet, and the #14-14 for fastening insulated roofing panels to steel purlins and crest fixing. The metal point is Hobson's point for drilling steel sections such as purlins, top hats, roofing and cladding. Both are C1022 hardened steel with a Class 4 finish.

XGRiP is a short thread under the head that holds the roofing tight against the seal, so the seal stays watertight even when the roof is walked on; Hobson's sheet says it holds the roofing profile if an external load is applied. Scratchguard, on the #12-14 48 to 80mm screws, protects the shank from the severe scratching or scouring that can happen when fixing metal roofing, which Hobson says improves corrosion resistance.

Fixing into timber battens or trusses instead? Use the Type 17 screw with XGRiP. For cyclone washers and stainless bi-metal screws, see roofing screws.

Which size and length?

• •#12-14: 12 gauge (5.5mm thread), 14 threads per inch, a coarse thread by Hobson's definition (up to 16 TPI), 14mm head, 5/16 inch hex drive. 37 to 80mm.
• •#14-14: 14 gauge (6.3mm thread), 14 TPI, 14mm head, 3/8 inch hex drive. 110 to 300mm, long enough to pass through insulated roofing panels into the purlin.
• •Length: Hobson measures hex screws with a flange or seal from under the head. Add up the sheet or panel thickness at the crest and the steel, then choose a length that leaves at least three threads protruding past the back of the steel, Hobson's rule for maximum pull-out in metal.
• •Steel thickness: Hobson publishes #12-14 pull-out values in steel 1.1 to 3.8mm thick and #14-14 values in steel 0.7 to 2.9mm thick, with drill tests in 2.0mm (#12-14) and 1.9mm (#14-14) G450 steel. It does not publish a maximum drilling thickness.

XGRiP tek screw sizes

Every size and length we carry. Every length comes unpainted or in the same 35 painted head colours. Select a row to open it in the selector, then pick the colour.

Pull-out values for roofing tek screws

Hobson publishes laboratory pull-out values for these screws in the steel grades and thicknesses below. They hold only for that steel. The working load includes a factor of safety of 2.5 for steel; Hobson notes safety factors should be considered for design and actual pull-out loads may differ depending on the base material.

Hobson gives no edge distance, spacing, sheet pull-over or wind uplift figures for these screws. How many screws go in each sheet and purlin comes from the roof sheeting maker's installation guide or the building designer, especially in high wind areas.

• •Screw strength (#12-14): torsional 10.9Nm; tensile 16,450N mean and 13,800N characteristic; shear 9,900N mean and 8,300N characteristic.
• •Screw strength (#14-14): torsional 16.9Nm; tensile 21,800N mean and 16,150N characteristic; shear 13,100N mean and 9,700N characteristic.
• •Drill test: 18kg load at 2,200 RPM; #12-14 through 2.0mm G450 in no more than 5.5 seconds per screw (4 seconds average), #14-14 through 1.9mm G450 in no more than 6 seconds (5 seconds average).

Painted heads in COLORBOND colours

The heads come unpainted or painted in these colours, as Hobson lists them (the names in brackets are the New Zealand names Hobson lists on its vmaX colour sheet, shortened here for Smooth Cream and Thunder Grey): Basalt, Blue Ridge (Pacific Blue), Bluegum, Bushland, Classic Cream (Smooth), Cottage Green (Permanent), Cove, Deep Ocean (Storm Blue), Dover White, Dune, Evening Haze, Gully, Headland (Maple), Ironstone, Jasper (Sorrell), Loft, Mangrove, Manor Red (Scoria), Monument, Night Sky (Ebony), Pale Eucalypt (Mist Green), Pale Terracotta, Paperbark, Plantation, Primrose, Sandbank (Straw), Shale Grey (Gull Grey), Southerly, Stone, Surfmist (Titania), Terrain, Wallaby, Wilderness (Rivergum), Windspray (Smokey) and Woodland Grey (Thunder). Pick the colour in the selector. Hobson's warranty covers the screw, not the paint. Hobson lists Bushland, Wilderness, Loft, Headland, Sandbank, Pale Terracotta, Blue Ridge, Plantation, Primrose and Stone as discontinued COLORBOND colours, painted on request, so ask us before ordering these. COLORBOND is a registered trademark of BlueScope Steel Limited.

Class 4 coating and warranty

Class 4 is a corrosion class for self-drilling screws (AS 3566.2). Hobson's finish guide describes it as a 38 micron mechanically galvanised coating for external use in severe marine environments, ISO 9223 corrosivity category C4. Hobson's self-drilling screw warranty gives these periods:

• •The warranty covers the structural integrity of the exposed head and washer only, not the threaded shank, and not staining, discolouration, coating dulling or paint degradation.
• •It asks for installation to Hobson's instructions with a screw gun at the recommended speed, and washing down with fresh water at least every six months in C2 and C3 and every three months in C4 and C5.
• •Roofs are exposed, so pick the class for the site. Class 4 is covered up to C4 (severe marine, industrial). Hobson does not recommend it in very severe marine (C5) sites, where its warranty covers only 316 bi-metal (see roofing screws).
• •Hobson says to get professional advice on the category for your site (ISO 9223 and AS 4312), or ask us. Extreme (CX) sites need Hobson's written confirmation first.

How to fit XGRiP roofing tek screws

1. Fit a 5/16 inch hex nut setter (#12-14) or 3/8 inch (#14-14) in a cordless screwdriver set between 2,200 and 3,000 RPM. Hobson does not recommend impact drivers.
2. Place the screw on the crest at the fixing position, square to the sheet.
3. Apply consistently firm pressure while the screw drills through.
4. Take care not to overtighten, as Hobson warns that sealing washer damage could result. As general practice, stop when the seal is pressed onto the sheet.
5. As general practice, sweep the metal swarf off the roof when you finish, before it rusts and stains the sheet.

Roofing tek screws in Adelaide

Allmat supplies XGRiP tek screws, roofing screws, stitching screws and nut setters to roofers, shed builders and trade across Adelaide and South Australia. Add them to a quote with the rest of your list and we will price the lot.

Questions