NASCLA Accredited Commercial General ContractorMetalsMedium
A contractor is evaluating different types of fasteners for attaching corrugated metal roof panels to steel purlins. The project specification requires a fastener that provides excellent resistance to vibration loosening and corrosion, and also seals the penetration point effectively. Which of the following fastener types is best suited for this application?
- ASelf-drilling screw with an EPDM washer
- BUnthreaded drive pin
- CStandard common nail
- DToggle bolt
Show answer & explanationAnswer & explanation
Correct answer: A. Self-drilling screw with an EPDM washer
Self-drilling screws eliminate the need for pre-drilling, and when combined with an EPDM washer, they provide excellent sealing against water intrusion and resist loosening due to vibration, which is crucial for metal roofing.
Why the other options are wrong
- B. Drive pins are typically for concrete or masonry and offer no sealing or easy removal.
- C. Nails offer poor vibration resistance and no sealing capability for metal roofing.
- D. Toggle bolts are for hollow walls and are unsuitable for attaching roof panels to purlins.
Self-Drilling Screws (with EPDM Washer)
Fasteners that drill their own pilot hole, tap their own threads, and are often paired with a synthetic rubber washer (EPDM) to provide a weather-tight seal and vibration resistance.
- Combine drilling, tapping, and fastening into one operation.
- EPDM washers are durable and resistant to UV and temperature extremes.
- Widely used for metal roofing, siding, and other sheet metal applications.
Memory trick: Roof Screws: Drill, Seal, Stay Firm.