Choosing the right metal roofing screws is the difference between a tight, leak-free roof and years of callbacks. This guide explains what to use and how to choose. You can answer the question confidently and get the job done right.
What Are Roofing Screws & Why They’re Different
Roofing screws are heavy-duty fasteners specifically made for securing roofing materials, especially metal panels, to the underlying structure. Unlike ordinary screws, roofing screws come with features that address the unique challenges of roof installation – namely exposure to weather, need for waterproofing, and the demands of attaching into structural members. These screws almost always have a hex-head or washer-head design with an integrated rubber washer (usually EPDM) under the head to create a watertight seal when tightened. This is a key difference from general-purpose screws: roofing screws form a gasketed seal that prevents rainwater from leaking through the screw hole. They are also typically made with corrosion-resistant coatings (such as galvanized zinc-aluminum or specialty coatings) or stainless steel to withstand years of sun, rain, and possibly salt if you’re in a coastal area. In short, roofing screws are purpose-built to handle outdoor elements and keep your roof panels firmly attached, whereas standard screws might rust or loosen, causing serious issues down the line.
Another difference is the self-drilling or self-tapping tip that many metal roofing screws have. Roofing fasteners often come with either a drill-point tip (for going through metal purlins without pre-drilling) or a sharp self-piercing tip (for piercing wood framing or thinner gauge metal). This allows installers to drive them straight through metal roofing sheets into the support structure in one step. Additionally, the threads of roofing screws are designed for strong holding power in the substrates (wood or metal purlins) – for example, some have coarse threads or special thread designs for better grip in wood, or twin threads for metal-to-metal applications.
Key Screw Types for Metal Roofing
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Self-piercing (sharp-point): Best for metal-to-wood; fast install, no pre-drill in wood.
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Self-drilling: Best for metal-to-metal/steel; drill-point tip eliminates pre-drilling in light–medium steel.
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Corrugated panel screws: Sized/washered for crest fastening on wavy profiles.
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Painted-head screws: Color-matched heads/washers for clean aesthetics plus extra head corrosion protection.
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Stainless-cap / stainless screws: Maximum corrosion resistance for coastal or harsh environments.
Tip: On exposed-fastener roofs, always use screws with EPDM washers.
How to Choose the Right Screw for Your Metal Roof
Picking the right roofing screw isn’t complicated once you understand a few key factors. The goal is simple: use a screw that matches your roof panel, structure, and environment. Here’s how to decide smartly:
1. Match the Screw to Your Substrate
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Wood framing or plywood → Use self-tapping (sharp-point) screws. They bite quickly and hold tight in wood fibers.
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Steel purlins or framing → Use self-drilling (Tek) screws with a drill-point tip that cuts through metal without pre-drilling.
Rule of thumb: Sharp point for metal-to-wood, drill point for metal-to-metal.
2. Consider Your Environment
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Inland or dry regions: Coated carbon-steel screws (zinc, Ruspert, or E-coating) are usually enough.
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Coastal, industrial, or high-humidity areas: Choose stainless steel or stainless-cap screws. They resist corrosion and last as long as the roof.
Think long-term, your fasteners should match the lifespan of the roof panels.
3. Get the Right Washer
Always use EPDM bonded washers on exposed fasteners. EPDM (synthetic rubber) seals tightly, resists UV rays, and prevents leaks. Avoid cheap PVC or neoprene washers that crack over time. The washer should compress slightly, forming a seal without bulging.
4. Choose Head Style and Finish
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Hex washer head: Standard for metal roofing—easy to drive, distributes pressure evenly.
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Painted head: Best for visible roofs; color-matched coatings blend with panels and add corrosion protection.
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Stainless or capped heads: For top-tier durability and a clean, rust-free appearance.
5. Pick Proper Size
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Gauge (thickness): #10–#14 are most common. Heavier gauge = stronger hold.
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Length: Long enough to pass through the panel, any insulation, and penetrate the substrate by at least 3 full threads (or 1 inch into wood).
Too short = weak grip; too long = unnecessary effort and potential damage.
6. Think About Appearance & Compatibility
Choose screws that match the panel color and metal type. For example, use stainless screws on aluminum panels to prevent galvanic corrosion. For modern homes, painted or low-profile heads give a cleaner finish.
Frequently Asked Questions About Roof Screws
Q1: Can I use regular wood screws on a metal roof?
No. Use roofing-grade screws with EPDM washers; regular wood screws lack sealing and proper coatings.
Q2: Where do I place screws on corrugated panels—crest or valley?
Typically on the crest (high rib) with a wide washer for the best seal. Follow the panel manufacturer’s instructions.
Q3: How tight should roofing screws be?
Tighten until the washer just compresses uniformly. If it bulges or extrudes, it’s over-tight.
Q4: How far apart should screws be?
Varies by panel spec and wind zone. Commonly every rib at edges/end laps and every 2nd–3rd rib in the field, aligned on supports.
Q5: What size screws are most common?
#10–#14 gauges are typical. Length depends on rib height and substrate; ensure enough embed (wood) or threads past steel.
Q6: When should I choose stainless or stainless-cap screws?
For coastal/high-corrosion sites or long-life roofs where you want the fasteners to last as long as the panels.
Q7: My screws are leaking—what now?
Check for loose screws or cracked washers. Replace with new roofing screws (often one size larger) and ensure proper torque.
Q8: Can I color-match the screws to the roof?
Yes, use painted-head roofing screws and matching washers.
Conclusion
Use roofing-specific screws matched to your substrate (sharp-point for wood, drill-point for steel), environment (coating vs. stainless), and profile (crest-fastening for corrugated). Install straight, compress the washer lightly, and follow consistent spacing. Inspect periodically and replace worn fasteners to keep the roof tight and dry.
Have a project and want help finalizing specs or sourcing high-quality roofing screws? Contact Fong Prean for expert guidance and options (including coated, painted-head, and stainless-cap fasteners) tailored to your application.