| Specification Type | Mainstream Range | Notes |
|---|---|---|
| Diameter (Metric) | M4.8, M5.5, M6.3 (3.5–6.3mm) | Most commonly M5.5 and M6.3 |
| Diameter (US) | #8, #10, #12, #14 (8–14 gauge) | #10 and #12 are standard for roofing |
| Length | 13–200mm (19–135mm mainstream) | Select based on roof panel + purlin thickness |
| Washer OD | 14–16mm | Fits corrugated metal roof ribs for full coverage |
Point: Type 17 (T17)
Thread: CSD (Coarse)
Application: Securing metal roofing sheets to wooden purlins, wooden roof structures, and agricultural greenhouses.
Point: #3 / #5 Self-Drilling
Thread: High-Low Thread (fine pitch for thin steel)
Application: Steel roof structures, metal purlins, PV mounting systems, and industrial wall cladding.
Washer: Large / Umbrella-shaped washer
Application: Securing insulation to insulated sandwich panels, preventing tearing.
Length = panel thickness + purlin thickness + 15-20 mm (minimum penetration into wood)
Drill Point: Choose T17 for wood; #3/#5 for metal (#5 for thicker steel).
Material: Carbon steel + Ruspert for general use; 316 stainless steel for coastal areas; 410 for general industrial use.
Tool: Hex socket power screwdriver. Torque control at 15-25N·m (varies by diameter and substrate) to avoid overtightening.
Spacing: Fix at roof ribs, spacing 300-600mm. Dense spacing at eaves and ridges.
Sealing: Ensure the EPDM washer lies flat and seamless. Do not reuse or disassemble the screw.
Hefeng Group focuses on manufacturing and supplying screws for real construction needs.
Over the past 10 years, we’ve worked with customers across North America, South America, and Southeast Asia, learning that consistency matters most in this business...[ Read More >>]
