Plastic Cap Nails for Underlayment
Products
5 products
Everwin
Everwin CAPTITE SCN25RBC Roll Cap Nailer, 1" | Contractor Pack
Stinger
Stinger 1" Stinger Plastic Cap 304 Stainless NailPac w/ Plastic Caps | Contractor Pack
Stinger
Stinger 1" Stinger Plastic Cap Electro-Galv NailPac w/Plastic Caps | Contractor Pack
Stanley Bostitch
Stanley Bostitch N66BC-1 Cap Nailer, 1-1/4" to 2-1/2" | Contractor Pack
Paslode
Paslode 3/8" x 1" Leg 18 Gauge Staple w/Plastic Cap | Contractor Pack
Why plastic cap nails are the right call for synthetic underlayment
The unsung hero of dry-in
Cap nails are the unsung hero of dry-in. The plastic disc spreads load wide enough that synthetic underlayment does not tear out at the fastener, which is exactly what happens when a cold front rolls in before you can shingle.
Every major synthetic underlayment manufacturer requires cap fasteners. Skip them and you skip the warranty.
Why a one inch cap beats a bare nail head
A plain roofing nail head is around 3/8 inch wide. Synthetic underlayment is a slick reinforced poly weave that resists tear-out far less than felt does. Wind gets under a flap, lifts the underlayment, and it rips clean off the small nail head.
A one inch plastic cap gives roughly seven times the bearing surface, and the underlayment stays put through 60 plus mph gusts. That single design detail is why every synthetic spec sheet calls for caps.
Picking the right plastic cap nails for your job
Use one inch caps for synthetic underlayment or 30 pound felt over half inch through five eighths inch decking. That is the everyday pick. Step up to one and a quarter inch in high wind zones, and reach for two inch caps when going through ice and water shield or layering over an existing underlayment.
Compatible cap tools include the Bostitch SL150, ProBilt PCN45, Hitachi and Metabo HPT NV45 cap variants, and the Stinger CN100. See our guide on choosing a nail gun for roofing felt for tool selection.
Frequently asked questions
- Why a plastic cap instead of a regular roofing nail?
- The 1" plastic cap distributes load across the underlayment so it doesn't tear out in wind before the shingles go on. Most synthetic underlayment manufacturers (GAF Tiger Paw, Owens Corning ProArmor, etc.) require cap fasteners. A regular roofing nail will void the warranty.
- 1 inch vs 2 inch cap nails — which?
- 1" is for synthetic underlayment and felt over 1/2" decking, the standard residential job. 2" is for ice-and-water shield over thicker decking, or when you're going through underlayment plus an existing layer. When in doubt, 1" handles 90% of jobs.
- Will any cap nailer fire any cap nail?
- Mostly yes — most cap nailers (Bostitch SL150, ProBilt PCN45, Hitachi NV45 cap, Stinger CN100) accept the standard 1" plastic cap collation. Always verify the gun's spec sheet for max length compatibility before buying 2" caps.
- Can I use a hammer tacker instead?
- For small repairs, sure. For a full roof, a pneumatic cap nailer is 5 to 10 times faster and gives consistent depth. Hammer tackers also use staples (not caps) which most synthetic underlayment manufacturers do not approve.