Hex Washer Self-Drilling Screws with EPDM Washer for Metal Roofing
The hex washer head self-drilling screw with EPDM sealing washer is the standard fastener for fixing profiled metal roof sheets and wall cladding to steel purlins. The case-hardened drill point drills, taps and fastens in a single operation, while the vulcanized weather-proofing washer forms a durable seal against wind-driven rain. As a dedicated roofing screw manufacturer, we supply this range in bulk to roofing contractors, steel builders and fastener distributors worldwide.
Features and Benefits
- Hex washer head with 8 mm / 5/16 in. socket drive — positive engagement under high installation torque
- Hardened drill point (No. 2 to No. 5) drills through structural steel up to 12 mm total thickness without pre-drilling
- Bonded EPDM washer hot-vulcanized to its metal backing — no washer separation, dual-sealing weather-tight joint
- Case-hardened core: surface hardness above HRC 53 with a tough HRC 32-40 core, resists stripping and torsional failure
- Multi-layer corrosion protection from 1,000 h (C3) up to 2,000 h (C4+) salt-spray classes
- Room-temperature mechanical coating process — no acid pickling, zero hydrogen embrittlement
Typical Applications
- Crest and valley fixing of corrugated and trapezoidal roof sheets to purlins
- Wall cladding and liner panels to steel girts
- Ridge capping, flashing, gutter and trim installation
- Insulated sandwich panel systems (winged point option prevents jacking through thick insulation)
- General steel-to-steel fabrication with drill capacities up to 12 mm total thickness
Model Specifications
| Thread Size | Drill Point | Max Steel Thickness | Length Range | Drive | Sealing Washer |
|---|---|---|---|---|---|
| #8-18 (4.2 mm) | No. 2 | 2.8 mm | 13-50 mm | 5/16 in. hex | EPDM 12 mm |
| #10-16 (4.8 mm) | No. 2 / No. 3 | 4.3 mm | 16-65 mm | 5/16 in. hex | EPDM 14 mm |
| #12-14 (5.5 mm) | No. 3 | 5.8 mm | 20-150 mm | 8 mm hex | EPDM 16 mm |
| #12-24 (5.5 mm) | No. 5 | 12.0 mm | 32-110 mm | 8 mm hex | EPDM 16 mm |
| #14-14 (6.3 mm) | No. 3 | 5.8 mm | 20-300 mm | 8 mm hex | EPDM 18 mm |
| #14-20 (6.3 mm) | No. 5 | 12.0 mm | 32-100 mm | 8 mm hex | EPDM 18 mm |
Material and Performance
- Material: case-hardened carbon steel C1022A / 10B21 to ISO 10666 and GB/T 3098.11
- Surface hardness: min. HRC 53; core hardness HRC 32-40 for ductility under vibration
- Coating options: zinc plating, yellow zinc or organic multi-layer finish graded C3 / C4 / C4+ (1,000-2,000 h neutral salt spray, ASTM B117)
- EPDM washer compound remains elastic from -40 °C to +120 °C with UV and ozone resistance
- RoHS compliant — free of lead, cadmium, mercury and hexavalent chromium
Installation Guidelines
- Use a screw gun of 0-2,500 rpm with a depth-sensitive nosepiece and the matching hex socket.
- Place the screw perpendicular to the sheet at the fixing position and apply firm, consistent end pressure.
- Let the drill point bore through the full steel stack before the thread engages — never force the speed.
- Stop driving when the EPDM washer compresses into a visible, uniform neoprene ring around the head.
- Confirm at least three full threads penetrate beyond the supporting steel for rated pull-out values.
An under-driven washer leaves a leak path; an over-driven washer splits the seal and cracks the coating. Both are rejected in our factory drive tests, and correct seating should be checked on the first fixings of every crew.
Why Source from BuildFastener
Every production lot is sampled for drill capacity, torsional strength, drive torque and salt-spray performance before packing. We support OEM head markings, custom packaging and mixed-size consolidation for export. Send us your panel and purlin schedule and our engineers will confirm drill-point selection, spacing and washer size for your project.
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