What Size Staples for Roofing Felt: Choosing Length, Crown, and Material

Selecting the right staple for roofing felt affects hold, tear resistance, and shingle warranty compliance. This guide explains recommended staple sizes, crown widths, materials, installer techniques, and manufacturer considerations to help ensure durable underlayment attachment on typical U.S. roof decks.

Application	Recommended Length	Crown Width	Material
Temporary Fastening Synthetic Underlayment To Sheathing	3/8″–1/2″	Narrow (1/4″) Or Standard (3/8″)	Galvanized Or Stainless
Permanent Attachment Of Asphalt Felt To Plywood/OSB	1/2″–9/16″	Standard (3/8″)	Hot-Dipped Galvanized Or Stainless
Thicker Decking Or Double Layers / High Wind Areas	9/16″–1″	Wide (1/2″) For Extra Grip	Hot-Dipped Galvanized Or Stainless

Why Staple Size Matters For Roofing Felt

Choosing staple size affects how well the underlayment resists wind uplift, tearing, and moisture intrusion. Too short a staple fails to penetrate the roof deck properly; too long can split sheathing or compromise insulation layers. Proper size also impacts compliance with shingle and underlayment manufacturer requirements and local building codes.

Staple Length: How Deep Should Staples Penetrate

Staple length should allow the legs to penetrate the roofing felt and embed securely into the roof deck without passing through entirely. Typical recommended lengths range from 3/8″ for lightweight synthetic underlayment to 9/16″ or 1″ for thicker decks or layered applications.

For 3/8″ plywood or OSB roof sheathing with single-layer felt, 3/8″–1/2″ staples are generally sufficient. For thicker sheathing or when fastening through two layers (double underlayment or insulation), choose 9/16″–1″ staples to ensure adequate embedment.

Crown Width: Narrow Vs. Wide Crowns

Crown width affects how the staple distributes load across the felt. Narrow crowns (about 1/4″) are useful for temporary placement or lighter materials, while standard (3/8″) and wide crowns (1/2″) provide greater pull-through resistance for permanent applications.

When roofing felt will be exposed to wind or when a more secure hold is required under shingles, use standard to wide crowns to reduce tear-through during wind events. Wide crowns also reduce the number of staples needed for equivalent holding power.

Staple Gauge And Form (Chisel Vs. Round Point)

Staple wire gauge affects strength. Heavier gauges (lower gauge number) increase shear and pull-out resistance. Common construction staples for roofing use 16–18 gauge wire; 16-gauge is stronger and better for high-wind zones.

Point type matters when penetrating hard or treated sheathing. Chisel points cut fibers and reduce splitting; round points push material aside and may be more likely to split brittle OSB or treated plywood. Choose chisel or ringed shank styles for higher holding power where available.

Material And Corrosion Resistance

Roofing felt is exposed to moisture and metals must resist corrosion. Hot-dipped galvanized or stainless steel staples are recommended for long-term durability. Electro-galvanized staples are cheaper but can corrode faster in coastal or high-humidity areas.

When installing underlayment under metal roofing or in corrosive environments, use Type 304 or 316 stainless staples to prevent rust stains and premature failure.

Manufacturer Requirements And Warranties

Many shingle and underlayment manufacturers include fastening specifications. Some shingle warranties require nails instead of staples for final shingle attachment, and some underlayment warranties limit or specify staple types and spacing. Failure to follow these guidelines can void product warranties.

Before choosing staples, review the underlayment and shingle installation instructions and any local building code requirements to ensure compliance.

Staple Spacing And Pattern For Roofing Felt

Proper spacing reduces wind uplift and tearing. For standard asphalt roofing felt, common practice is spacing staples 6″–8″ along the edges and 12″–18″ in the field, though synthetic underlayment may allow wider spacing per manufacturer instructions.

In high-wind or exposed locations, reduce spacing and use wider crowns and heavier gauge staples to improve resistance to blow-off and abrasion prior to shingle installation.

Tools And Installation Tips

Pneumatic staple guns increase speed and consistency. Set the compressor and tool for the substrate thickness to avoid overdriving or underdriving staples. Test on scrap sheathing to confirm proper depth and adjust pressure accordingly.

Install felt flat and wrinkle-free. Place staples near laps and perimeters first, then in the field, keeping staples flush without tearing the felt. Avoid stapling too close to the edge where the material can tear out.

When Staples Are Not Recommended

Some manufacturers and roofers prefer nails over staples for final fastening of shingles due to superior withdrawal resistance. Staples may be acceptable for temporarily holding underlayment, but nails are often specified for shingles and long-term attachment.

Local codes and insurance requirements sometimes require nails. Check local building codes and the particular shingle/underlayment instructions before choosing staples as the primary fastener.

Special Cases: Synthetic Underlayments, Metal Roofs, And Insulated Decks

Synthetic underlayments are lighter and often require shorter staples such as 3/8″–1/2″ when used on standard sheathing. Many synthetic manufacturers list approved fastener lengths and crown widths in their installation guides.

Under metal roofing or on insulated decks where penetration depth must be controlled, use stainless staples or screws with washers designed for the substrate to avoid thermal movement issues and corrosion.

Common Mistakes And How To Avoid Them

• Using Staples That Are Too Short: Results in poor holding power and underlayment blow-off. Select length that fully embeds into sheathing.
• Overdriving Staples: Weakens the felt and reduces holding power. Adjust pneumatic gun pressure and test first.
• Ignoring Manufacturer Instructions: Can void warranty. Always follow product-specific fastening guidance.

Quick Reference Guide

Scenario	Recommended Staple Length	Crown Width	Material
Temporary placement of synthetic underlayment	3/8″–1/2″	1/4″–3/8″	Galvanized
Permanent asphalt felt on plywood/OSB	1/2″–9/16″	3/8″	Hot-Dipped Galvanized or Stainless
High-wind or double layer	9/16″–1″	1/2″	Hot-Dipped Galvanized or Stainless

Final Selection Checklist

• Confirm Manufacturer Requirements: Review underlayment and shingle instructions for fastener specs.
• Match Staple Length To Deck Thickness: Ensure legs embed into the sheathing without over-penetration.
• Choose Appropriate Crown Width And Gauge: Wider crowns and heavier gauges for high-wind areas.
• Select Corrosion-Resistant Material: Use hot-dipped galvanized or stainless in corrosive environments.
• Test Tool Settings: Trial staples on scrap to set depth and pressure correctly.

Following these recommendations helps ensure underlayment remains secure until the final roofing layer is installed and supports long-term roof performance. When in doubt, consult product literature or a qualified roofing professional to match fastener choice to the specific roof system and local code.