Single-ply membrane and flexible sheet roofing systems - EPDM, TPO, PVC and bituminous membranes - protect warehouses, sports halls and industrial plants across every climate. These roofs are only as reliable as the fasteners that anchor the insulation boards and membrane to the structure beneath, which is why the purlin tail screw is one of the most engineered products in our range.
How Membrane Roofing Systems Are Fixed
A typical build-up runs: steel deck or purlins, vapour barrier, rigid insulation boards, and finally the waterproof membrane. In mechanically fixed systems, the membrane is clamped through the insulation into the deck with stress plates and screws. Every fixing is a potential leak path and a thermal bridge - so the screw must seal itself, hold against wind uplift, and not conduct heat out of the building.
The Role of Purlin Tail Screws
Purlin tail screws carry a long shank that passes through up to 200 mm of insulation and terminates in a self-drilling point sized for the steel purlin flange. A colour-matched plastic or metal cap, closed by an EPDM washer, covers the head after installation so water cannot reach the thread. The result is a fixing that is simultaneously structural, sealing and thermally broken.
Fixing Pattern & Best Practices
- Follow the membrane manufacturer's declared fixing pattern - typically rows at 200-300 mm centres along sheet edges, 500 mm in the field, with extra fixings at corners, perimeters and penetrations.
- Screw length = insulation thickness + deck thickness + minimum 10 mm embedment; never let the point bottom out before the washer seats.
- Drive perpendicular to the deck; angled fixings cut oversized holes in the membrane and reduce uplift capacity.
- Use stress plates sized to the insulation density - undersized plates crush rigid boards and lose clamp force.
Typical Applications
- EPDM, TPO and PVC single-ply membrane roofs on steel deck
- Bituminous torch-on and self-adhesive membranes
- Insulated warehouse and factory roofs with PIR, PUR or mineral wool boards
- Retrofit over-roofing with additional insulation layers
Why Choose BuildFastener
Our purlin tail screws are manufactured with consistent point geometry for one-shot installation through insulation, matched colour caps for the leading membrane systems, and salt-spray tested coatings for 25-year design life. Full wind-uplift test data is available on request.
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