C1022 Hardened
Stitching Screw
Stitching screws for joining the side laps of metal roof and wall sheets, flashings and thin sheet metal.
About the Stitching Screw
Stitching screws join the overlapping side laps of metal roof and wall sheets, flashings and other thin sheet metal, so the laps sit tight and do not rattle. They come as #8-15 large wafer head screws from 12 to 40mm (Class 3 or zinc yellow, unpainted or in Dover White, Monument and Surfmist), #8-09 coarse thread wafer screws (zinc yellow, unpainted or Dover White), and Class 4 flange hex screws in #8-15 x 12mm and #10-12 x 20mm, in boxes of 1,000. Choose the head, coating, colour and length above; the guide below covers choosing, pull-out values and fitting.
Also called stitch screws, side lap screws or stitching tek screws.
Features
- Large wafer head spreads load
- Joins sheet-to-sheet laps
- Needle and metal points
- Class 3, Class 4 and zinc yellow finishes
Applications
- Side laps on metal roof and wall sheeting
- Flashings and cappings
- Sheet to sheet stitching
What stitching screws are for
A stitching screw joins sheet to sheet. Where two sheets of roofing or wall cladding overlap at the side lap, or where a flashing laps onto a sheet, a row of stitching screws pulls the laps tight and holds them closed. Hobson lists its stitching screws for sheet metal stitching, thin gauge sheet steel and general fixing of lightweight steel.
They are self-drilling screws with a needle point, the point Hobson uses on general purpose screws, made to pierce and drill thin sheet rather than heavy steel. For fixing the sheet down to steel purlins or battens, use roofing screws or tek screws; stitching screws hold the sheets to each other.
Large wafer or flange hex?
- Large wafer head, Phillips drive: a low, wide head (10.5mm across, 1.3mm high on the #8-15) that clamps a wide area of thin sheet and sits low on the lap. Drive with a Phillips #2 bit.
- Flange hex head: a hex with a built-in flange, driven with a nut setter: 1/4 inch hex on the #8-15 x 12mm, 5/16 inch on the #10-12 x 20mm. Class 4 coated.
- Want a sealing washer under the head? The needle point stitching screws with a seal are on their own page.
- Length: Hobson measures large wafer and flange hex screws from under the head. Pick a length that goes through all the laps with thread to spare; for maximum pull-out in metal, Hobson's guide asks for at least three threads protruding through the back of the steel.
Stitching screw sizes
Every stitching screw we carry. Size is gauge and threads per inch (TPI) x length: #8 is 4.2mm across the thread and #10 is 4.8mm. All are coarse thread by Hobson's definition (up to 16 TPI). Hobson publishes no data sheet for the #8-09 coarse thread screws.
Size as gauge-TPI x length in mm, as listed in the selector. Boxes are the minimum order. Tap a number to show it in the selector above.
| Size | Head, coating and colour | Box |
|---|---|---|
| Large wafer, Phillips, Class 3, unpainted | ||
| #8-15 x 12mm | Large wafer, Phillips, Class 3, unpainted | Boxes of 1,000 |
| #8-15 x 16mm | Large wafer, Phillips, Class 3, unpainted | Boxes of 1,000 |
| #8-15 x 20mm | Large wafer, Phillips, Class 3, unpainted | Boxes of 1,000 |
| #8-15 x 25mm | Large wafer, Phillips, Class 3, unpainted | Boxes of 1,000 |
| #8-15 x 32mm | Large wafer, Phillips, Class 3, unpainted | Boxes of 1,000 |
| #8-15 x 40mm | Large wafer, Phillips, Class 3, unpainted | Boxes of 1,000 |
| Large wafer, Phillips, Zinc yellow, unpainted | ||
| #8-09 x 25mm | Large wafer, Phillips, Zinc yellow, unpainted | Boxes of 1,000 |
| Large wafer, Phillips, Zinc yellow, Dover White | ||
| #8-09 x 25mm | Large wafer, Phillips, Zinc yellow, Dover White | Boxes of 1,000 |
| Large wafer, Phillips, Zinc yellow, unpainted | ||
| #8-09 x 29mm | Large wafer, Phillips, Zinc yellow, unpainted | Boxes of 1,000 |
| Large wafer, Phillips, Zinc yellow, Dover White | ||
| #8-09 x 29mm | Large wafer, Phillips, Zinc yellow, Dover White | Boxes of 1,000 |
| Large wafer, Phillips, Zinc yellow, unpainted | ||
| #8-15 x 12mm | Large wafer, Phillips, Zinc yellow, unpainted | Boxes of 1,000 |
| #8-15 x 16mm | Large wafer, Phillips, Zinc yellow, unpainted | Boxes of 1,000 |
| #8-15 x 20mm | Large wafer, Phillips, Zinc yellow, unpainted | Boxes of 1,000 |
| #8-15 x 25mm | Large wafer, Phillips, Zinc yellow, unpainted | Boxes of 1,000 |
| #8-15 x 32mm | Large wafer, Phillips, Zinc yellow, unpainted | Boxes of 1,000 |
| #8-15 x 40mm | Large wafer, Phillips, Zinc yellow, unpainted | Boxes of 1,000 |
| Large wafer, Phillips, Class 3, Dover White | ||
| #8-15 x 12mm | Large wafer, Phillips, Class 3, Dover White | Boxes of 1,000 |
| #8-15 x 16mm | Large wafer, Phillips, Class 3, Dover White | Boxes of 1,000 |
| #8-15 x 20mm | Large wafer, Phillips, Class 3, Dover White | Boxes of 1,000 |
| #8-15 x 25mm | Large wafer, Phillips, Class 3, Dover White | Boxes of 1,000 |
| #8-15 x 32mm | Large wafer, Phillips, Class 3, Dover White | Boxes of 1,000 |
| #8-15 x 40mm | Large wafer, Phillips, Class 3, Dover White | Boxes of 1,000 |
| Large wafer, Phillips, Class 3, Monument | ||
| #8-15 x 40mm | Large wafer, Phillips, Class 3, Monument | Boxes of 1,000 |
| Large wafer, Phillips, Zinc yellow, Dover White | ||
| #8-15 x 12mm | Large wafer, Phillips, Zinc yellow, Dover White | Boxes of 1,000 |
| #8-15 x 16mm | Large wafer, Phillips, Zinc yellow, Dover White | Boxes of 1,000 |
| #8-15 x 20mm | Large wafer, Phillips, Zinc yellow, Dover White | Boxes of 1,000 |
| #8-15 x 25mm | Large wafer, Phillips, Zinc yellow, Dover White | Boxes of 1,000 |
| #8-15 x 32mm | Large wafer, Phillips, Zinc yellow, Dover White | Boxes of 1,000 |
| #8-15 x 40mm | Large wafer, Phillips, Zinc yellow, Dover White | Boxes of 1,000 |
| Large wafer, Phillips, Zinc yellow, Surfmist (Titania) | ||
| #8-15 x 25mm | Large wafer, Phillips, Zinc yellow, Surfmist (Titania) | Boxes of 1,000 |
| Flange hex, Class 4, unpainted | ||
| #8-15 x 12mm | Flange hex, Class 4, unpainted | Boxes of 1,000 |
| #10-12 x 20mm | Flange hex, Class 4, unpainted | Boxes of 1,000 |
Stitching screw pull-out and strength values
Hobson publishes laboratory test values for three of its stitching screw ranges: the Class 3 unpainted #8-15 large wafer and the two Class 4 flange hex screws, all measured in 0.55mm G550 steel sheet. They hold only for that sheet; Hobson notes actual pull-out loads can differ with the base material and that safety factors should be considered for design. Hobson's drill test for each is a 13kg load at 2,200 RPM, drilling 0.55mm G550 in no more than 1.5 seconds per screw. Hobson does not publish a thickest sheet these screws will drill.
Pull-out in 0.55mm G550 sheet and screw strengths in newtons (1,000N = 1kN), from Hobson's DRiLLX performance data sheets. Mean = average of the samples tested; characteristic = 95% of screws are expected to exceed it; working load includes Hobson's factor of safety of 2.5 for steel. Shear and tensile columns are Hobson's characteristic values. No values are published for the zinc yellow, Dover White, Monument or Surfmist screws or the #8-09 screws. Tap a number to show it in the selector above.
| Screw | Pull-out, mean | Pull-out, characteristic | Pull-out, working | Shear, characteristic | Tensile, characteristic |
|---|---|---|---|---|---|
| #8-15 large wafer, Class 3, unpainted | 650 | 550 | 200 | 3,850 | 6,400 |
| #8-15 x 12mm flange hex, Class 4 | 650 | 550 | 200 | 3,550 | 5,900 |
| #10-12 x 20mm flange hex, Class 4 | 1,150 | 1,000 | 400 | 4,100 | 6,800 |
Class 3, Class 4 or zinc yellow: which coating?
Class 3 and Class 4 are corrosion classes for self-drilling screws (AS 3566). Hobson's self-drilling screw warranty gives these periods by ISO 9223 corrosivity category; zinc yellow is not covered by it:
- Hobson calls its category names indicative only, and where a site sits between two categories the higher one applies. Get professional advice on your site's category (ISO 9223 and AS 4312), or ask us.
- The warranty covers the structural integrity of the exposed head, not the shank or the look of the coating or paint.
- Colours: the large wafer screws come unpainted or in Dover White, Monument and Surfmist, COLORBOND steel colour names, to suit sheeting in those colours. COLORBOND is a registered trademark of BlueScope Steel Limited.
- The Surfmist screw and the zinc yellow Dover White screws are zinc yellow underneath, which Hobson rates for low-corrosion environments or temporary fixing and does not cover under its warranty. For exposed roofing and cladding, choose the Class 3 Dover White or Monument screws.
Corrosion warranty periods in years from Hobson's self-drilling screw warranty (effective September 2025). NR = not recommended. Zinc yellow: Hobson's finish comparison recommends it for low-corrosion environments or temporary fixing.
| Environment | Class 3 | Class 4 | Zinc yellow |
|---|---|---|---|
| C2: urban, inland | 20 | 25 | Not covered |
| C3: moderate marine, industrial | 10 | 20 | Not covered |
| C4: severe marine, industrial | NR | 15 | Not covered |
| C5: very severe marine, industrial | NR | NR | Not covered |
How to fit stitching screws
- Use a cordless screwdriver set at no more than 2,500 RPM with a Phillips #2 bit for large wafer heads, or the 1/4 or 5/16 inch hex nut setter for flange hex heads. Hobson does not recommend impact drivers.
- Hold the laps together, place the screw on the lap and keep firm, steady pressure on the driver while the point drills through.
- Stop when the head pulls the sheets snug. Take care not to overtighten: thin sheet strips easily.
- Sweep the metal swarf off the sheet when you finish, before it rusts and stains the surface.
Stitching screws in Adelaide
Allmat supplies stitching screws, roofing screws, tek screws and driver bits to roofers, cladders, shed builders and trade across Adelaide and South Australia. Add them to a quote with your roofing screws and we will price the lot.
Stitching screws for roofing, cladding and flashings
Stitching screws, roofing screws, tek screws and the driver bits to suit are available to order from Allmat for roofers, cladders, shed builders, plumbers and trade across Adelaide and South Australia. Order through Allmat, we pick and pack it, then click and collect from the Allmat yard or have it delivered to site.
Goes with
Questions
What are stitching screws used for?
Joining sheet to sheet: stitching the side laps of steel roof and wall sheeting, and fixing flashings to sheets, so the laps stay tight. Hobson lists them for sheet metal stitching, thin gauge sheet steel and general fixing of lightweight steel. To fix sheeting down to purlins or battens, use roofing screws.
What size stitching screw should I use?
The #8-15 large wafer is the common one, from 12 to 40mm long. Use a length that passes through all the laps with thread to spare. For a hex drive, choose the #8-15 x 12mm or #10-12 x 20mm Class 4 flange hex.
How thick a sheet can a stitching screw drill?
Hobson's data sheets test them in 0.55mm G550 sheet and list them for thin gauge sheet steel; they do not give a maximum thickness. For heavier steel, use a tek screw with a metal drill point.
Do stitching screws need a washer?
These have no sealing washer: the large wafer head clamps the sheet on its own. If you want a seal under the head, choose the needle point stitching screws with seal.
Class 3 or Class 4 stitching screws?
Under Hobson's warranty, Class 3 is covered for 20 years in C2 (urban, inland) and 10 years in C3 (moderate marine, industrial), and not recommended in C4 or C5; Class 4 is covered for 25, 20 and 15 years in C2, C3 and C4. In severe marine (C4) sites Hobson does not recommend Class 3: use Class 4.
Do you have coloured stitching screws?
Yes: large wafer stitching screws in Dover White, Monument and Surfmist, as well as unpainted. The Surfmist screw and the zinc yellow Dover White screws are zinc yellow underneath: Hobson rates that for low-corrosion environments only and does not cover it under its warranty. For exposed roofing and cladding, use the Class 3 Dover White or Monument screws.
Where can I buy stitching screws in Adelaide?
Order through Allmat. Order ahead by phone on 1300 03 03 63 or send your list for a quote, then click and collect from 25 Kapara Road, Gillman, or have them delivered to site.
Stitching Screw: sizes and finishes we supply
32 lines by type and finish. Pick one above for its product code and pack sizes.
| Head | Finish | Sizes | Lengths | Lines |
|---|---|---|---|---|
| Large wafer | Zinc Yellow Passivate | #8-09, #8-15 | 12, 16, 20, 25, 29, 32, 40mm | 17 |
| Large wafer | Class 3 | #8-15 | 12, 16, 20, 25, 32, 40mm | 13 |
| Flange hex | Class 4 | #8-15, #10-12 | 12, 20 inch | 2 |
Data sheets and documents
The documents for the product you choose are listed with the selector above. Here is every Stitching Screw document from Hobson Engineering.
All Stitching Screw documents (11)
Data sheets and technical data (7)
Did You Know flyers (1)
Need them in bulk?
Add the sizes you need to your quote, or send us your list and we’ll price the lot and supply it with the rest of your order.
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