A felt roof only looks as good as the fixing line holding it down. Choose staples that are too short, too narrow or poorly protected, and the felt can tear, lift or rust-stain long before the job should need attention. The best staples for roofing felt are not simply the biggest box at the lowest price. They are the right gauge, crown, leg length and coating for the felt, the timber and the exposure the roof will face.
For merchants and contractors, this is a category where a dependable specification earns repeat orders. Roofing teams need staples that feed cleanly, drive consistently and hold without damaging the membrane. That means choosing for the job rather than treating every roll of felt as the same.
Start with the roofing system, not the staple gun
“Roofing felt” can mean several different products on site. It may be traditional bitumen shed felt, an underlay beneath tiles or slates, or a heavier cap sheet used on an outbuilding or flat roof. The correct fixing method changes with the system.
For pitched-roof underlays, staples are commonly used to secure the material temporarily or as part of the specified installation method before battens and the final covering are fitted. They are not a substitute for battens, approved nails or proprietary fixings where the membrane manufacturer requires them. For exposed shed felt and similar coverings, staples can help position laps and edges, but galvanised clout nails, felt nails or adhesive are often needed for the final weatherproof detail.
That distinction matters. A staple that is perfectly capable of holding underlay in place during installation may not be suitable as the only fixing on a roof exposed to wind, rain and temperature movement. Check the felt manufacturer’s instructions first, then match the staple to the stated method.
Best staples for roofing felt: the working specification
For most timber-based roofing underlay work, a galvanised, medium-wire staple with a broad crown is the practical starting point. A crown around 10 to 11mm spreads pressure across the felt better than a narrow-crown staple. This reduces the chance of the legs cutting through the material when it is tensioned or moves slightly with temperature changes.
Leg length is the next decision. The staple must penetrate the timber adequately without firing through thin boarding or creating avoidable damage on the underside. In many roofing felt applications, 14mm to 20mm staples suit common softwood battens, rafters and boarding. The right size depends on the felt thickness, any overlap and the timber section.
A short 10mm or 12mm staple may hold light membrane during initial positioning, but it can be marginal where there are overlaps, wind exposure or less forgiving timber. A 16mm staple is often a useful all-round trade size for standard underlay work. Step up to 18mm or 20mm only when the timber depth and fixing requirement support it. More leg length does not automatically mean more security if it blows through thin OSB, plywood or board edges.
Wire gauge also affects performance. Fine-wire staples can be quick and neat, but they are more likely to tear softer felt under load. Medium-wire staples offer a stronger balance for general roofing use. Heavy-wire staples have their place in demanding timber fixing work, but can be too aggressive for some membranes unless specifically approved. The objective is firm retention without crushing, puncturing or splitting the material.
Galvanised or stainless steel?
Corrosion resistance should reflect the roof’s exposure and how long the fixing is expected to remain in service. For standard underlay beneath a finished roof covering, quality galvanised staples are usually the sensible commercial choice. They provide good protection, suit fast-paced installation and keep the cost per fixing under control.
For coastal areas, highly exposed sites, agricultural buildings or applications where the staple may remain closer to moisture, stainless steel is the safer option. It costs more, but it avoids the false economy of early corrosion, staining and callbacks. If the felt will be permanently exposed, do not assume an ordinary galvanised staple is enough. Use the fixing type prescribed for that roofing product and detail.
Electro-galvanised staples are common and can perform well for protected internal or covered applications. Where moisture exposure is more demanding, specify a coating and material grade that are fit for the environment rather than relying on a basic plated finish.
Crown width protects the felt
The crown is the bridge across the top of the staple. On roofing felt, it does more than join two points of wire. A wider crown spreads the load over a larger area, helping keep the material intact when the roof sees wind pressure or movement.
Narrow-crown staples are designed for precision fixing and can bite into felt too sharply. They may look tidy on installation, then pull through at the first point of stress. Wide-crown staples are generally the stronger choice for felt, membranes and other sheet materials because they hold the surface rather than concentrating force in a small strip.
There is a limit. An excessively wide crown can be awkward around close details, narrow battens and tight lap work. For most roofing underlay jobs, a standard wide-crown pattern gives the best balance of holding area, tool availability and consistent feed performance.
The staple gun must match the fixing
A reliable staple is wasted in the wrong tool. Before stocking up or loading a gun, confirm crown width, leg-length range, wire gauge and staple series. Many pneumatic and cordless staplers accept only a specific family of staples, and a near match is not a match.
Using an incompatible staple can cause jams, poor drive depth and inconsistent firing. On a roof, that costs more than time. It can leave proud staples that snag the next layer, crush the felt where the gun is overpowered, or create loose fixings where the driver blade is not seating properly.
Pneumatic staplers remain a strong choice for volume work where an air line is practical. They are quick, light in the hand and consistent when set up correctly. Cordless tools offer greater freedom on repairs, smaller roofs and sites where dragging a hose is a nuisance. Either way, set the depth on scrap timber first. The staple crown should sit flat against the felt, not slice into it and not stand proud.
Common mistakes that cause roofing-felt failures
The most frequent error is driving staples too close to the edge of a lap. Felt needs enough material beyond the fixing to resist tearing. Stapling through a stressed edge or an uneven fold gives the wind a starting point.
Overdriving is another regular problem. A staple sunk hard into the felt may appear secure, but it has weakened the surface. Underdriving is no better, as proud crowns can catch on the next course or prevent the felt from lying flat. Good depth control matters as much as staple length.
Spacing should follow the roofing system and manufacturer guidance. Where no specific schedule is provided for temporary positioning, avoid random, wide gaps that allow the membrane to flap, and avoid excessive stapling that fills the underlay with unnecessary perforations. Secure the material flat, maintain the proper laps and let the permanent roofing components do the work they are designed to do.
Finally, never use staples as a workaround for damp, rotten or poorly fixed timber. The strongest staple cannot make a sound fixing in unsound substrate. If battens, deck boards or rafters are compromised, deal with the substrate before applying the roof covering.
A practical buying brief for trade counters
For a fast-moving roofing-felt staple line, keep the range focused around the jobs customers actually carry out. A sensible core offer includes:
- Galvanised wide-crown, medium-wire staples in 14mm, 16mm and 18mm lengths for general underlay and felt work.
- Longer options where regular users fit through thicker laps into suitable timber sections.
- Stainless steel alternatives for coastal, agricultural and higher-exposure work.
- Clearly matched staples for the most common pneumatic and cordless staple-gun formats.
Clear labelling is commercially useful here. State the crown width, leg length, coating, compatible tool series and intended application on the box. Contractors do not want to decode a fixing range on a wet roof, and counter staff should be able to identify the right staple without guesswork.
A staple is a small part of a roof, but it has a direct effect on installation speed and finished reliability. Stock trade-grade wide-crown staples with credible corrosion protection, sensible size options and consistent collation, and the choice becomes straightforward: specify the fixing that holds the felt securely without damaging it, every time the gun is pulled.