M8 J-bolts for securing roofing sheets to purlins. Zinc plated for corrosion resistance. Sold in boxes of 100 with sizes from 60mm to 300mm to suit different purlin depths and sheet profiles.
Size
Price
QTY
M8 x 60
£16.68£20.02
M8 x 80
£17.89£21.47
M8 x 100
£19.98£23.98
m8 x 120
£23.80£28.56
m8 x 130
£29.98£35.98
m8 x 140
£23.91£28.69
M8 x 150
£25.89£31.07
M8 x 160
£29.90£35.88
M8 x 180
£28.95£34.74
M8 x 200
£32.98£39.58
M8 x 220
£34.90£41.88
M8 x 240
£37.90£45.48
M8 x 260
£48.90£58.68
M8 x 280
£49.90£59.88
M8 x 300
£54.90£65.88
J hook bolts are the standard fixing for securing corrugated and profiled roofing sheets to timber or steel purlins. The hooked end wraps around the purlin while the threaded shank passes through the sheet, allowing you to clamp everything tight with a washer and nut. Simple, effective, and used on agricultural buildings, industrial units and outbuildings across the UK for decades.
These M8 j-bolts come in a practical box of 100, with lengths ranging from 60mm right up to 300mm. That range covers everything from thin single-skin sheets on shallow purlins through to insulated composite panels on deeper sections. Pick the length that gives you enough thread showing above the sheet to get your nut on properly usually you want 20-30mm of thread protruding once everything is pulled down tight.
Why J-Bolts Work So Well on Roofing Jobs
The beauty of the j-bolt is its simplicity. No drilling into the purlin, no special tools, no fiddly clips. You hook it over, drop it through the sheet at the crown of the corrugation, add your sealing washer and nut, and tighten up. On a decent-sized roof you can fix hundreds in a day without breaking a sweat. The zinc plating gives reasonable protection against corrosion, though on coastal or particularly exposed sites you might want to consider stainless alternatives for the long term.
Choosing the Right Length
Getting the bolt length right matters more than people think. Too short and you will not get enough thread engagement. Too long and you are wasting money and leaving excess thread poking up that looks untidy. Measure your purlin depth, add your sheet thickness, add 25mm for the washer and nut, and you are in the right area. When in doubt, go one size longer rather than shorter you can always cut thread off, but you cannot add it back on.
These j-bolts are a proper trade staple. Nothing fancy, just a reliable fixing that does exactly what it needs to do. Box of 100 means less time ordering and more time fitting.
Pro Tip: Always fit j-bolts at the crown of the corrugation rather than the trough. Water runs in the troughs so any fixing there becomes a potential leak point.
J-bolts are used across agricultural, industrial and light commercial roofing wherever profiled or corrugated sheets need fixing to purlins. Common applications include barn roofs, portal frame buildings, lean-tos, covered yards and workshop roofing. They work with fibre cement sheets, metal profile sheets and most standard corrugated materials. Suitable for both new installations and repair work where existing fixings have failed or sheets need replacing.
Best For
Corrugated roofing sheet installation
Agricultural and industrial buildings
Portal frame roof cladding
Fibre cement and metal profile sheets
Lean-to and outbuilding roofs
Compatible Materials
Timber purlins
Steel purlins and zed sections
Corrugated fibre cement sheets
Metal profile roofing sheets
Bitumen corrugated sheets
Key Features
M8 thread diameter
Zinc plated finish
Lengths from 60mm to 300mm
Box quantity of 100
Hook design grips purlins securely
Not suitable for: Not recommended for standing seam or secret-fix roofing systems. For coastal or highly corrosive environments, stainless steel j-bolts would be a better long-term choice.
Hook the curved end of the j-bolt over the purlin from above, positioning it where the sheet corrugation crown will sit. Lay the sheet and align the pre-drilled hole or drill through at the crown. Drop the threaded shank through, fit a sealing washer and nut, then tighten until the washer compresses slightly without crushing. Work systematically along each purlin for consistent results.
Position the j-bolt hook over the purlin at the fixing point
Ensure the threaded shank faces upward through the sheet line
Lay the roofing sheet with the bolt passing through the crown of the corrugation
Fit a roofing sealing washer over the thread
Add the nut and tighten until the washer seals without over-compressing
Check alignment and adjust sheet position before fully tightening all fixings
Work along each purlin row to maintain even sheet tension
How do I know what length j-bolt to use?
Add together your purlin depth, sheet thickness and around 25mm for the washer and nut. For an 80mm deep purlin with a standard profile sheet, a 120mm or 130mm bolt usually works well. When in doubt, go slightly longer.
Do I need to use sealing washers with j-bolts?
Yes. A proper roofing sealing washer with a rubber or EPDM backing is essential to prevent water ingress at the fixing point. The washer should compress slightly when tightened to form a watertight seal.
Can these j-bolts be used with steel purlins?
Yes, j-bolts work with both timber and steel purlins including zed sections and C-sections. The hook grips around the purlin flange in the same way. Just make sure the hook size suits your purlin profile.
These j-bolts feature an M8 metric thread with a formed hook end designed to wrap over standard purlin sections. The zinc plated finish provides basic corrosion protection suitable for most inland and sheltered applications. Manufactured to common roofing fixing dimensions with lengths calibrated to suit typical purlin depths and sheet thicknesses used in UK agricultural and industrial construction.
Thread Diameter
M8
Available Lengths
60mm to 300mm
Finish
Zinc plated
Box Quantity
100
Head Type
J-hook (formed hook end)
Application
Roofing sheet to purlin fixing
Size
M8 x 100, m8 x 120, m8 x 130, m8 x 140, M8 x 150, M8 x 160, M8 x 180, M8 x 200, M8 x 220, M8 x 240, M8 x 260, M8 x 280, M8 x 300, M8 x 60, M8 x 80
