Nails for Roof Felt: Choosing the Right Roofing Nails for Tar Paper

The installation of roof felt, or tar paper, relies on selecting the proper nails to ensure a watertight, durable underlayment. This guide covers the best types of nails, suitable lengths and gauges, installation patterns, and maintenance tips to help United States homeowners and professionals achieve reliable roof protection.

Overview Of Roof Felt And Nail Requirements

Roof felt serves as an additional weather barrier beneath shingles, helping to shed moisture and provide a spill-resistant surface for shingle nailing. The nails used with roof felt must create a secure seal without tearing the material. Compatibility with the felt’s thickness, climate exposure, and shingle type are key considerations. For many residential applications, the nails should resist corrosion, penetrate adequately without tearing the felt, and have heads that seal effectively against wind-driven rain.

Types Of Nails Used With Roof Felt

Several nail types are commonly used with roof felt, each serving different durability and corrosion resistance needs:

• Galvanized Roofing Nails offer good rust resistance at an economical price and are suitable for typical wooden decks and standard felt installations.
• Stainless Steel Roofing Nails provide superior corrosion resistance, making them ideal for humid climates, coastal environments, or roofs with long service life expectations.
• Aluminum Roofing Nails are lightweight and resistant to corrosion, though they may be less common in certain thicker felt applications.
• Coated Nails with polymer or ceramic coatings can reduce friction and corrosion, extending life in some conditions.

For asphalt shingles over felt, a common practice is to use ring-shin or specially designed roofing nails to prevent withdrawal and improve holding power. Bare, smooth nails can work but may increase the risk of loosening in high-wind areas.

Choosing The Right Length And Gauge

The goal is to secure the felt without tearing it while providing enough penetration into the substrate to resist wind uplift. The following guidelines help determine appropriate dimensions:

• Length: Most roof felt installations use nails in the range of 1 inch to 1 1/4 inches when the felt is paired with standard shingle angles. For thicker felt or solid decking, consider 1 1/4 inch to 1 1/2 inch nails to ensure adequate substrate penetration.
• Gauge: Common gauges are 11 (heavier) and 12 (slightly lighter). A heavier gauge nails tolerate repeated thermal cycling and provide greater pull resistance in windy conditions.
• Head Size: A wider head helps seal against the felt and reduces the risk of tear-out during installation. Look for roofing nails with a broad, flat head that creates a tight seal with minimal damage to the felt.

When in doubt, follow the shingle manufacturer’s recommendations and local building codes, as these specify compatible nail lengths and gauges for the combination of felt, attic space, and climate zone.

Fastening Patterns And Installation Tips

Proper nail placement is essential for performance and wind resistance. Consider these best practices:

• Spacing: Nails for roof felt are typically placed at regular intervals along the edges of the felt sheets and at staggered intervals in the field. Common edge spacing is 6 to 8 inches on center; field spacing is 12 to 18 inches.
• Angle: Drive nails perpendicular to the surface to prevent loosening and tearing. Avoid angled nailing that can pinch or crack the felt.
• Surface Prep: Ensure the decking is clean, dry, and free of protrusions. Remove splinters or nails from previous layers that could interfere with the new felt.
• Pilot Holes: For dense decking or hard woods, predrilling small pilot holes can reduce splitting and improve nail seating, though many contractors rely on the sharp point of roofing nails to penetrate without predrilling.
• Sealing: In wet climates or exposed locations, consider a compatible sealant or asphalt-based adhesive along the felt edges and underlayment overlaps to enhance moisture barriers, though this is not always necessary when using proper nails and fasteners.

Always follow the manufacturer’s installation instructions for roofing felt and shingles, as improper nailing can compromise the underlayment and the roof’s overall performance.

Materials And Corrosion Resistance

Durability under exposure to sun, moisture, and temperature fluctuations is a key concern. Corrosion resistance directly affects performance and lifespan. Some practical considerations:

• Environment: Coastal and high-humidity areas increase corrosion risk; stainless steel or coated nails are often preferred there.
• Material Compatibility: Ensure the nail material does not react adversely with the felt or any underlying tar compounds. Most modern roofing nails are designed to be chemically compatible with typical roof underlayments.
• Quality: Avoid low-quality or fragmented nails, which can lead to premature failure, rust streaks, or tearing of the felt.

Durability is enhanced when nails resist bending, have consistent heads, and maintain a stable bite through weather cycles. When replacing roof felt or performing major repairs, select nails with proven performance in the local climate.

Common Mistakes And Maintenance

Avoid these missteps to extend the life of roof felt installations:

• Using Inappropriate Nails—choosing nails without adequate corrosion resistance or incorrect length can lead to leaks and failed underlayment.
• Over-Tightening—driving nails too deeply can tear the felt or damage decking, while under-driving may allow wind uplift.
• Inconsistent Spacing—uneven nail spacing creates weak points and increases the risk of moisture intrusion.
• Ignoring Climate Considerations—not adapting nail type, length, or gauge to regional weather can shorten roof life.

Routine inspection after installation helps detect loose nails, rust streaks, or signs of moisture. Promptly address any issues by re-nailing with appropriate materials and resealing overlaps where needed.

Tools And Accessories

Having the right tools helps ensure a clean, effective installation. Consider the following:

• Nail Gun or Hammer: A roofing nail gun speeds installation and provides consistent drive depth; a reliable hammer is useful for adjustments and in tight spaces.
• Safety Gear: Wear eye protection and gloves; roof work requires fall-protection measures when working on elevated surfaces.
• Measuring Tools: A tape measure and chalk line help maintain even spacing and alignment across sheets of felt.
• Sealant And Accessories: If the project requires, use compatible asphalt-based sealants for overlaps or edges, as recommended by the felt manufacturer.

Choosing quality nails and appropriate accessories ensures a durable underlayment that supports shingles and resists weathering for years to come.