Product Overview Hex washer head self-drilling roofing screws (also known as Tek screws, self-drilling screws, or drill tail screws) are self-drilling, self-tapping fasteners designed for fastening metal roofing sheets, steel cladding, and lightweight steel structures to steel or timber substrates. The distinctive hexagonal washer head provides a large bearing surface and is driven with a standard hex socket or nut driver, while the integrated EPDM-bonded sealing washer creates a watertight seal around the drilled hole — making these screws the industry standard for roofing and cladding applications. These screws are manufactured to DIN 7504 K (hexagon washer head) and ISO 15480 standards. The self-drilling point (Type 17 or Tek point) eliminates the need for pre-drilling — the screw drills its own pilot hole through steel sheets up to 12.5 mm thick, then forms a mating thread in the substrate. Available in diameters #12 (5.5 mm), 4.8 mm, 5.5 mm, and 6.3 mm, with lengths ranging from 19 mm to 150 mm. The screws are available with zinc plating (standard) or hot-dip galvanized (HDG) finish for enhanced corrosion resistance. The HDG option is strongly recommended for Middle East coastal projects and Central Asian outdoor infrastructure where exposure to humidity, salt air, and temperature extremes demands superior corrosion protection. Compared with standard self-tapping screws, hex washer head self-drilling roofing screws offer faster installation (one-step drilling and fastening), superior clamping force (large hex washer head distributes load evenly), and reliable sealing (EPDM washer prevents water ingress). This makes them the preferred choice for metal roofing, wall cladding, HVAC ductwork, and solar panel mounting systems. Standard & Compliance Parameter Specification Standard DIN 7504 K (hexagon washer head self-drilling screw); ISO 15480 Material C1018 / C1022 carbon steel (case-hardened) Core Hardness HV 250–400 Surface Hardness HV 560–650 (case-hardened) Thread Type Self-drilling thread (ST), Type 17 point Head Type Hexagonal washer head with integrated EPDM sealing washer Finish Options Zinc plated (Cr3/Cr6-free), hot-dip galvanized (HDG), Dacromet Zinc Coating 5–12 μm (electro-galvanized); 45–85 μm (HDG) Sealing Washer EPDM bonded washer (UV-resistant, temperature range −40 °C to +120 °C) Temperature Range −20 °C to +120 °C (standard) Drilling Capacity Up to 12.5 mm steel plate (depending on screw diameter) Size Range & Specifications Screw Size Diameter (mm) Standard Lengths (mm) Hex Drive Application #12 5.5 19 / 25 / 32 / 38 / 50 8 mm Light roofing, cladding 4.8 4.8 19 / 25 / 32 / 38 / 50 / 65 8 mm Standard roofing, HVAC 5.5 5.5 25 / 32 / 38 / 50 / 65 / 75 8 mm Heavy roofing, steel cladding 6.3 6.3 25 / 32 / 38 / 50 / 65 / 75 / 100 / 125 / 150 8 mm / 10 mm Heavy-duty roofing, structural connections Custom lengths and diameters available upon request. Product Features Self-Drilling Point (Tek Point) — The hardened drill point penetrates steel sheets up to 12.5 mm thick without pre-drilling, reducing installation time and labor costs. Hex Washer Head — Large bearing surface distributes clamping force evenly and prevents damage to roofing sheets. Compatible with standard hex socket drivers. EPDM-Bonded Sealing Washer — The UV-resistant EPDM washer compresses against the roofing sheet to create a watertight seal, preventing water ingress at the fastener penetration point. Case-Hardened Construction — Surface hardness of HV 560–650 provides excellent drill point durability, while the tougher core (HV 250–400) resists torsional breakage during installation. Corrosion-Resistant Finishes — Zinc plating (standard) offers reliable protection for general use; hot-dip galvanized (HDG) option provides C4/C5 corrosion resistance per ISO 12944 for coastal and harsh environments. Wide Range of Sizes — Diameters from 4.8 mm to 6.3 mm, lengths from 19 mm to 150 mm, covering virtually all roofing and cladding requirements. Applications Hex washer head self-drilling roofing screws are widely used in: Metal Roofing Installation — Fastening corrugated and trapezoidal steel roofing sheets to purlins, rafters, and steel frames. Wall Cladding — Attaching metal wall panels, sandwich panels, and composite cladding to steel or timber structures. HVAC Ductwork — Securing duct insulation, hangers, and flashing. Solar Panel Mounting — Fastening mounting rails and brackets to roof structures. Steel Framing — Light-gauge steel framing connections for partitions and ceilings. Agricultural Buildings — Poultry houses, barns, warehouses, and storage sheds. Industrial Sheds — Factory roofs, workshop buildings, and warehouse roofing. Installation Guidelines Select the correct screw length — The screw should penetrate the substrate by at least 25 mm beyond the total thickness of the material being fastened. Use a variable-speed screwdriver — Drive at low speed (1,500–2,500 RPM) with steady pressure until the EPDM washer compresses slightly against the roofing sheet. Do not over-tighten — Excessive torque will compress the EPDM washer beyond its elastic limit and cause water leakage or damage to the roofing sheet. Drive perpendicular to the surface — Angled installation prevents the washer from seating properly and creates an incomplete seal. Inspect after installation — Check that all washers are properly compressed and no screws are over-driven or protruding. Quality Assurance All screws are manufactured under strict quality control and can be supplied with: Mill Certificates — material test reports with chemical composition and mechanical properties Hardness test reports — core and surface hardness verification Salt spray test reports — for corrosion resistance verification Third-party inspection reports (SGS, BV, TÜV) — available upon request EN 10204 3.1 Inspection Certificates — available upon request Ordering Information To place an order or request a quotation, please provide: Screw size (#12, 4.8 mm, 5.5 mm, 6.3 mm) Length(s) required Surface finish (zinc plated / HDG / Dacromet) Quantity per size Certification requirements Packaging preferences Specifications are subject to change without prior notice. Please contact our sales team for the latest technical data sheets and customized solutions. FAQ for Hex Washer Head Self-Drilling Roofing Screws — Central Asia & Middle East Markets Below are the most frequently asked questions from buyers in Central Asia (Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan, Turkmenistan) and the Middle East (UAE, Saudi Arabia, Qatar, Kuwait, Oman, Bahrain), with standard answers.