Conxtruct
Solar Hanger Bolt Kit
304 stainless solar hanger bolt kits: dual-thread bolts that screw into timber or steel purlins through the roof sheet, with the seal and nuts to mount solar rail brackets.
About the Solar Hanger Bolt Kit
Solar hanger bolts fix solar panel rail brackets to the roof frame through the roof sheet, with a seal so the hole stays watertight. They are 304 stainless dual thread kits: NW21 for timber framed roofs (M8, M10 and M12, 150 to 400mm) and RWA22 for metal framed roofs with steel battens (M10 x 200 and 250mm), each with a black EPDM sealing washer and nuts, into a pre-drilled hole. Choose the size and length above; the guide below covers which kit suits which roof, pilot hole sizes and fitting.
Also called solar screw kits or dual thread solar screws.
Features
- 304 stainless steel
- Dual thread design
- EPDM sealing washer (black)
- Three ISO 4161 / DIN 6923 flanged hex nuts
- Nuts with locking serration
- Supplied assembled
- Sizes M8 to M12
Applications
- Mounting solar panels on timber-framed roofs
- Solar array roof fixing
- Suits most roof cladding types
- Fixing solar rails to timber or steel purlins through metal roofing
What a solar hanger bolt is
A solar hanger bolt is a dual thread screw: a screw thread at one end that goes into the roof frame, and a machine thread (M8, M10 or M12) at the other that carries the solar panel mounting bracket. Hobson supplies them assembled with a black EPDM based TPV (thermoplastic vulcanizate) sealing washer and the nuts, in 304 stainless, with an external hex drive. A pre-drilled hole is required.
Hobson's installation drawings show the kit passing through the rib of the roof sheeting into the frame, with the sealing washer on top of the rib and the bracket clamped between nuts on the machine thread. Hobson says the kits suit most types of roof cladding.
NW21 or RWA22: timber or steel roof frame?
- NW21 (timber): for mounting solar panels on timber framed roof structures. Kit: one EPDM sealing washer and three 304 stainless hex flange nuts with locking serrations (ISO 4161 / DIN 6923); the M8 kits also have a flat washer. M8, M10 and M12, 150 to 400mm.
- RWA22 (steel): for metal framed roof structures, fixing into steel battens or brackets with a self-tapping thread in a pre-drilled hole. Kit: one EPDM sealing washer, one stainless washer (ISO 7089 / DIN 125), two hex nuts (DIN 934) and two hex flange nuts with locking serrations (ISO 4161 / DIN 6923). 8mm screw with an M10 machine thread, 200 and 250mm. Hobson's RWA22 data covers supporting steel 2.0 to 10.0mm thick (grades S235 to S355). For thinner battens it gives no data: follow the mounting system maker or an engineer.
- Follow the solar mounting system maker's fixing specification (fixing type, size, embedment and spacing) and the roofing maker's guidance; where it calls for a different fixing, use that.
Solar hanger bolt sizes and dimensions
Every kit we carry. Select a row to open that size and length.
Machine thread x overall length (L). Screw diameter (D), machine thread length (Lm), screw thread length (Ld) and screw thread pitch (P) in mm from Hobson's NW21 and RWA22 data sheets. Hobson gives a 14mm cladding seal hole (CS) for every kit. Pack is the box quantity. Tap a number to show it in the selector above.
| Size | Kit | Screw dia | Machine thread | Screw thread | Pitch | Pack |
|---|---|---|---|---|---|---|
| NW21 kit, timber framed roofs | ||||||
| M8 x 150mm | NW21 kit, timber framed roofs | 8mm | 65mm | 65mm | 3.6mm | 50 |
| M8 x 200mm | NW21 kit, timber framed roofs | 8mm | 95mm | 65mm | 3.6mm | 25 |
| M10 x 160mm | NW21 kit, timber framed roofs | 10mm | 70mm | 70mm | 4.5mm | 25 |
| M10 x 200mm | NW21 kit, timber framed roofs | 10mm | 90mm | 70mm | 4.5mm | 25 |
| M10 x 250mm | NW21 kit, timber framed roofs | 10mm | 140mm | 70mm | 4.5mm | 25 |
| M12 x 200mm | NW21 kit, timber framed roofs | 12mm | 100mm | 80mm | 5.0mm | 25 |
| M12 x 250mm | NW21 kit, timber framed roofs | 12mm | 100mm | 100mm | 5.0mm | 25 |
| M12 x 300mm | NW21 kit, timber framed roofs | 12mm | 150mm | 100mm | 5.0mm | 15 |
| M12 x 350mm | NW21 kit, timber framed roofs | 12mm | 200mm | 100mm | 5.0mm | 15 |
| M12 x 400mm | NW21 kit, timber framed roofs | 12mm | 200mm | 100mm | 5.0mm | 15 |
| RWA22 kit, metal framed roofs (steel battens or brackets) | ||||||
| M10 x 200mm | RWA22 kit, metal framed roofs (steel battens or brackets) | 8mm | 110mm | 70mm | Not listed | 25 |
| M10 x 250mm | RWA22 kit, metal framed roofs (steel battens or brackets) | 8mm | 160mm | 70mm | Not listed | 25 |
Pilot hole sizes
Both kits need a pre-drilled hole. Hobson's suggested hole sizes:
Pilot hole diameters in mm from Hobson's NW21 (timber) and RWA22 (steel) data sheets. The RWA22 sheet covers steel 2.0 to 10.0mm thick only; thinner battens are not covered. Tap a number to show it in the selector above.
How a solar hanger bolt goes in
- Choose the kit for the roof frame: NW21 for timber, RWA22 for steel battens or brackets, in the size and length your mounting system specifies.
- Pre-drill the pilot hole in the frame to the size in the table (timber: by size and softwood or hardwood; steel: by steel thickness).
- Drive the kit into the frame with the external hex drive on the machine thread end, through the rib of the roof sheet as Hobson's drawings show, so the EPDM sealing washer sits on the sheeting.
- Fit the mounting bracket on the machine thread and clamp it between the nuts.
- RWA22 in steel: Hobson gives a maximum setting torque of 18 Nm.
Capacities and wind loads
Hobson's NW21 and RWA22 sheets list characteristic strength values, which we do not publish: they are not a design rating for an array, and the NW21 sheet gives no pull-out value in timber. That design, including fixing size, embedment and spacing, comes from the solar mounting system maker or an engineer.
304 stainless on the roof
- Kit, nuts and washers: 304 stainless steel. Hobson's corrosion guide for metal connectors lists 304 or 316 stainless as suitable for exposed work in every zone it covers, except within 2m of a pool edge, where it calls for 316.
- Even stainless can visibly corrode where salt spray builds up on it in severe coastal spots, so rinse it as part of the roof's normal maintenance.
Solar hanger bolts in Adelaide
Allmat supplies solar hanger bolt kits, roofing screws, nuts and washers to solar installers and roofers across Adelaide and South Australia. Add the kits to a quote with the quantity per array and we will price the lot.
Solar hanger bolts for the roof
NW21 and RWA22 solar hanger bolt kits are available to order from Allmat for solar installers, roofers and electricians 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 is a hanger bolt for solar panels?
A dual thread screw with a screw thread for the roof frame and a machine thread for the solar mounting bracket. Hobson's kits come assembled with an EPDM sealing washer and the nuts, in 304 stainless.
Which kit for a timber roof and which for a steel roof?
NW21 for timber framed roofs (M8, M10 and M12). RWA22 for metal framed roofs, fixing into steel battens or brackets (M10, 200 and 250mm). Hobson's RWA22 data covers supporting steel 2.0 to 10.0mm thick (grades S235 to S355). For thinner battens it gives no data: follow the mounting system maker or an engineer.
Do I need to pre-drill?
Yes, both kits need a pre-drilled hole. In timber, Hobson suggests 4, 5 and 6mm in softwood and 6, 7.5 and 9mm in hardwood for M8, M10 and M12. In steel, 6.8mm for 2 to 5mm steel, 7.0mm for 6mm and 7.2mm for 8 and 10mm.
What length solar hanger bolt do I need?
The length your solar mounting system specifies for your roof sheet profile and frame. Our NW21 kits run from 150 to 400mm and the RWA22 kits are 200 and 250mm; the table above gives each kit's machine and screw thread lengths.
Will they suit Kliplok or Trimdek?
Hobson says the kits suit most types of roof cladding and its drawings show the kit through the rib of the sheet; it does not name particular profiles. Follow the mounting system maker's guidance for your sheet.
How much wind load can a solar hanger bolt take?
We do not publish the characteristic values on Hobson's sheets: they are not a design rating for the array. The fixing design comes from the solar mounting system maker or an engineer.
What size socket drives them?
They have an external hex drive on the machine thread end. Match the socket to the hex on the kit, or ask us for the size before you order.
Where can I buy solar hanger bolts 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.
Solar Hanger Bolt Kit: sizes and finishes we supply
12 lines by type and finish. Pick one above for its product code and pack sizes.
| Kit | Finish | Sizes | Lengths | Lines |
|---|---|---|---|---|
| NW21 (timber) | 304 Stainless | M8, M10, M12 | 150, 160, 200, 250, 300, 350, 400 | 10 |
| RWA22 (steel) | 304 Stainless | 8/M10 | 200, 250 | 2 |
Data sheets and documents
The documents for the product you choose are listed with the selector above. Here is every Solar Hanger Bolt Kit document from Hobson Engineering.
All Solar Hanger Bolt Kit documents (5)
Data sheets and technical data (2)
Did You Know flyers (1)
Guides and articles (2)
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.
Browse all self-drilling screws