Type 17 Roofing Screws: A Comprehensive Guide for Metal Roofing

Self-drilling Type 17 roofing screws are a common choice for securing metal roofing panels. They combine a sharp self-drilling point with a durable, weatherproof washer to seal penetrations in metal surfaces. This article explains what Type 17 screws are, how they differ from other roofing fasteners, and best practices for selecting and installing them on American roofs.

What Are Type 17 Roofing Screws

Type 17 roofing screws are specifically engineered for metal roofing installations. The “Type 17” designation refers to the self-drilling point used on the screw, which is designed to cut through metal sheets with minimal friction. These screws typically feature a built-in washer made of neoprene or thermoplastic material that compresses against the panel, creating a weather-tight seal. The combination of a self-drilling tip, robust core, and washer seal makes Type 17 screws well-suited for corrugated, ribbed, and standing-seam metal roofs.

Key Features And Benefits

• Self-Drilling Point: The Type 17 point is sharp and angled to penetrate metal quickly without a pilot hole in most applications.
• Integrated Washer: A flexible washer seals the penetration to resist water intrusion and wind uplift.
• Corrosion Resistance: Screws are available in coatings such as zinc, galvanization, stainless steel, or polymer coatings to match roofing material and climate.
• Variety Of Head Styles: Options include hex washer head and pancake (low-profile) head, chosen for ease of driving and aesthetic considerations.
• Compatibility: Designed for metal panels like steel or aluminum, including standing-seam and corrugated profiles.

Materials And Coatings

Material selection affects longevity and performance in different environments. Common options include:

• Carbon Steel With Zinc Coating: Offers good corrosion resistance at a lower cost, suitable for temperate climates.
• Galvanized Steel: Enhanced protection against rust, widely used in residential and commercial applications.
• Stainless Steel: Superior corrosion resistance, ideal for coastal or high-humidity areas, but more expensive.
• Polymer or Ceramic Coatings: Provide additional weather resistance and color-matching capabilities for specific roof designs.

Sizing And Head Type Considerations

Choosing the right length and head style depends on panel thickness and substrate. Consider these guidelines:

• Length: The screw should penetrate the roof deck by about 1/2 inch to 3/4 inch, depending on deck material and insulation. Typical lengths range from 1 inch to 1-1/4 inches for common residential roofs.
• Thread Type: Type 17 screws use a fine or medium pitch suitable for metal. The thread should grip the panel without causing tearing.
• Head Style: Hex washer heads are common for power tools, while pancake heads offer a lower profile for a smoother roof surface. The head type can influence aesthetics and water sealing performance.
• Washer Size: A larger washer distributes load and helps sealings across uneven panel surfaces.

Compatibility With Roofing Materials

Type 17 screws are versatile for metal roofing, including:

• Galvanized Steel Panels: Common in many homes, these panels take Type 17 screws well when matched with compatible coatings.
• Aluminum Panels: Lighter roofs benefit from corrosion-resistant screws, particularly in coastal zones.
• Standing-Seam Roofs: Self-drilling Type 17 screws with proper sealing work effectively for securing panels to solid decks or batten systems.
• Corrugated Metal Roofs: The Type 17 point aids in clean penetration without excessive drilling.

Installation Best Practices

Proper installation ensures a long-lasting roof seal and strong performance. Consider the following steps:

• Pre-Check: Inspect panels for burrs or damage; mark screw locations per manufacturer guidelines to maintain panel alignment.
• Drill Point Engagement: Use an impact driver or screw gun with a clutch to avoid over-tightening, which can deform panels or strip threads.
• Sealing And Gasket Pressure: Ensure washers seat evenly without twisting or pinching. If the washer is deformed, replace the screw.
• Torque Control: Apply sufficient torque to seal the washer while avoiding overtightening that may cause leaks or panel damage.
• Pattern And Spacing: Follow manufacturer recommendations for spacing and pattern, typically staggered rows for standing-seam or uniform rows for corrugated panels.
• Deck Clearance: Verify deck material thickness and any insulation requirements to select the correct screw length.

Maintenance, Replacement, And Longevity

Metal roofs benefit from periodic inspection of fasteners. Consider these maintenance tips:

• Inspection Frequency: Inspect after severe weather, wind events, or seasonal transitions.
• Corrosion Watch: Look for rust around fasteners in galvanized or untreated metals and replace corroded screws promptly.
• Seal Integrity: Check washers for compression or cracking; damaged seals should be replaced to prevent leaks.
• Repository Of Spare Parts: Keep a small supply of the same Type 17 screws in the correct length and coating for future maintenance or panel replacements.

Common Pitfalls To Avoid

• Wrong Length: Too-short screws fail to penetrate the deck properly; too-long screws can pierce insulation or underside surfaces.
• Incompatible Coatings: Mixing dissimilar coatings can accelerate galvanic corrosion in certain climates.
• Over-Tightening: Excessive torque can strip threads, crack metal, or crush the washer seal.
• Skipping Pre-Drill Checks: In dense decks or thick panels, failure to account for deck thickness can compromise hold and seal.

Cost Considerations And Availability

Type 17 roofing screws are widely available through hardware retailers, building supply stores, and online vendors. Prices vary by material, coating, and head style. For large projects, buying in bulk may reduce unit costs. When selecting screws, balance initial cost with expected longevity in the given climate to optimize overall project value.

Choosing The Right Screws For Your Project

To select the best Type 17 roofing screws, consider climate, roof material, deck composition, and aesthetic preferences. Match the screw coating to the metal finish and local corrosion risks. Ensure the length accommodates deck thickness, insulation, and panel profile. Finally, confirm compatibility with the chosen head style and installation equipment to ensure a secure, weather-tight roof.