Metal Roofing Screws

For fastening metal roofing panels, use #12 x 1-inch construction fasteners metal roofing screws with Type 3 self-drilling points for wood substrates or #12 x 7/8-inch screws with Type 3 points for steel purlins up to 1/4-inch thickness. Specify hex washer heads with bonded EPDM washers providing 1-inch diameter sealing area. When sourcing from manufacturers like Cheng Hao, request screws with corrosion-resistant coatings compatible with your panel material: zinc-coated for steel panels, aluminum or stainless for aluminum panels, stainless for copper or coastal applications. For commercial installations over thicker steel substrates, upgrade to Type 5 points capable of drilling 1/2-inch steel. Verify that washers meet ASTM D1056 specifications for ozone and UV resistance, ensuring the weather seal survives 20-30 years of exposure.

EPDM (ethylene propylene diene monomer) washers on construction fasteners metal roofing screws create weathertight seals through controlled compression between the screw head and roof panel surface. During installation, proper torque compresses the EPDM washer from its original 3-4mm thickness to approximately 1.5-2mm, causing the elastomer to flow and conform to panel contours while maintaining recovery force against the head. The washer must compress sufficiently to seal surface irregularities yet retain enough thickness to maintain sealing pressure through thermal cycling and panel expansion. Cheng Hao manufactures metal roofing screws with bonded EPDM washers meeting ASTM D1056 grade 2A1 specifications, providing resistance to ozone, UV radiation, and temperature extremes from -40°F to 300°F, with projected service life exceeding 25 years when properly installed.

Point type selection for construction fasteners metal roofing screws depends on maximum steel substrate thickness: Type 2 points drill up to 1/8-inch steel (16-18 gauge), Type 3 points drill 1/4-inch steel (12-14 gauge), Type 4 points drill 3/8-inch steel, and Type 5 points drill 1/2-inch steel. For wood substrates, Type 17 points provide optimal performance. Most residential metal roofing uses Type 3 points over wood or light-gauge steel purlins. Commercial applications with heavier structural steel require Type 4 or Type 5 points. Using insufficient point capacity causes point deformation, wallowed holes, and installation failures, while oversized points waste cost and may split wood substrates. Specify point type based on the thickest substrate the screw will penetrate, ensuring reliable drilling performance without pre-punching or excessive tool wear.