Type 17 Roofing Screws: A Practical Guide for Homeowners and Pros
Type 17 roofing screws are a staple fastener for securing roofing materials to wooden decks and plywood sheathing. They feature a sharp self-drilling point, integrated washer, and a star or Phillips drive designed for quick installers and durable holding power. This guide explains what Type 17 screws are, where they excel, and how to choose and install them correctly for American roofing projects.
What Type 17 Screws Are
Type 17 roofing screws are self-drilling fasteners specifically engineered for roofing applications. The “Type 17” designation refers to the screw’s self-drilling point geometry, which helps it cut through wood and create threads as it is driven in. A built-in washer seals against moisture and distributes pressure to prevent leaks. The drive style (often Torx/Star or square drive) reduces cam-out and speeds installation. These screws come in various lengths and diameters to accommodate different roof materials and substrate thickness.
Key Features and Benefits
- Self-Drilling Point: Eliminates the need for pre-drilling in most wood substrates, saving time on installation.
- Integrated Washer: Provides a waterproof seal to minimize leaks around the screw head.
- Corrosion Resistance: Common coatings include stainless steel, galvanized, ceramic-coated, and polymer-coated options for durability in exposed conditions.
- Drive Type: Torx/Star drives offer better torque transfer and reduce stripping, improving long-term performance.
- Thread Design: Type 17 threads are optimized for wood, providing good pullout resistance and holding power without excessive splitting when used with the correct bit size.
Applications and Suitable Roof Materials
Type 17 screws are versatile for multiple roofing scenarios in the United States. They are commonly used to fasten asphalt shingles, composite roofing, and metal panels to wooden sheathing or decking. When dealing with metal roofs, ensure the screw’s thread matches the substrate and that the washer size adequately covers the penetration to prevent leaks. For cedar or softwood, Type 17 screws reduce splitting when properly driven at the recommended depth.
How Type 17 Compares to Other Roofing Screws
Understanding how Type 17 stacks up against other common roofing screws helps in selecting the right fastener for a project.
- Type 1: Features a coarse thread for softwood but lacks the self-drilling point optimized for rapid roofing installations; less common for metal roofing.
- Type 3: A finer thread often used for metal-to-metal connections; may require pre-drilling in wood substrates.
- Type 17 vs. Type 8: Type 17 is typically faster for wood decking due to its self-drilling point; Type 8 (fine thread) can be preferable for metal or dense substrates.
Lengths, Gauges, and How to Choose
Selecting the right length and gauge is critical for a secure roof. The screw should penetrate through the roofing material and into the deck by a minimum of 1/2 inch, depending on material thickness and local code requirements. Common sizes include #8 or #9 gauge with lengths ranging from 1 inch to 2-1/2 inches or longer for thicker decks. Coatings and materials (stainless, zinc-coated, ceramic-coated) impact corrosion resistance and cost. For high-wind zones, longer screws and more robust coatings help resist pullout and wind uplift.
Installation Best Practices
- Pre-Check: Inspect the substrate for rot or soft spots; replace damaged sections before installation.
- Avoid Over-Driving: Set a consistent depth to prevent dimpling the roofing material or compressing the washer excessively.
- Tooling: Use a high-torque impact driver with a suitable driver bit to minimize cam-out and strip.
- Spacing: Follow material manufacturer guidelines for screw spacing, typically 6 inches on center across panels and 12 inches at edges, depending on the roof type.
- Warranty and Codes: Verify local building codes and manufacturer warranty requirements for fastener type and coating.
Coatings and Corrosion Resistance
Coatings protect Type 17 screws from rust and staining, especially in coastal or humid climates. Common options include:
- Galvanized: Economical and suitable for moderate exposure areas.
- Ceramic-Coated: High heat and corrosion resistance for longer life under sun exposure.
- Stainless Steel: Superior corrosion resistance for harsh environments but at a higher cost.
- Polymer-Coated: Provides smooth driving and additional moisture barrier.
Buying Guide: What to Look For
- Material: Match substrate (pine, fir, plywood) and exposure level with screw material (stainless, galvanized, coated).
- Coating Type: Choose based on climate: coastal or salty air favors stainless or ceramic-coated products.
- Thread and Head: Type 17 thread for wood decking; ensure washer diameter covers the hole adequately.
- Drive: Torx/Star drives reduce cam-out and improve installation speed.
- Certifications: Look for fasteners meeting applicable ASTM or AO standards and manufacturer warranties.
Common Mistakes to Avoid
- Using Inappropriate Length: Too-short screws fail to penetrate adequately, reducing holding power.
- Overlooking Substrate Condition: Rotten or soft decking drastically reduces performance.
- Neglecting Sealant: Failing to install or replace underlayment or sealing washers in coastal environments.
- Mixing Coatings: Using mismatched coatings in the same area can lead to galvanic corrosion.
Maintenance and Longevity
Periodic inspection after severe weather is recommended. Look for rust around screw heads, loose shingles, or any gaps near washers. Replacing compromised screws promptly helps maintain roof integrity and prevents leaks. In high-wine or salt-prone areas, consider replacing with stainless steel Type 17 screws for extended life.
FAQ
- Do Type 17 screws require pre-drilling? Not usually, thanks to the self-drilling point, but pre-drilling may be necessary for especially dense material or if the manufacturer recommends it.
- Are Type 17 screws suitable for metal roofs? They can be used for metal panels if the thread design is compatible with metal-to-wood fastening; verify with the material supplier.
- Which coating lasts longest in coastal environments? Stainless steel and ceramic-coated screws offer the best corrosion resistance in salt-prone areas.