What is the difference between a roofing nail and a siding nail?
Short answer. A roofing nail has a short shank and a wide, flat head of at least 3/8 inch to hold thin shingles without tearing through, and is typically 1 1/4 inches long. A siding nail is usually longer and slimmer with a smaller head, often ring shanked, designed to pass through siding and sheathing into the framing and sit neatly on the face of wood or fiber cement siding.
Roofing nails
- Length: mostly 1 to 2 inches, with 1 1/4 inch standard for shingles.
- Head: 3/8 inch minimum by code, often larger, to resist pull-through on soft asphalt shingles.
- Shank: 11 or 12 gauge, usually smooth, sometimes ring shank.
- Coating: galvanized, stainless, aluminum or copper, as the IRC requires.
- Job: pin shingles to a wood deck with at least 3/4 inch of penetration or all the way through.
Siding nails
- Length: commonly 1 1/2 to 2 1/2 inches or more, long enough to reach studs through siding and sheathing.
- Head: smaller, so it can sit flush on wood or fiber cement siding and be painted over.
- Shank: often ring or spiral shank for withdrawal resistance in wood.
- Coating: hot dipped galvanized or stainless, with stainless preferred for cedar to avoid black streaks.
The vinyl siding overlap
Vinyl siding needs a wide head and is hung loosely so panels can slide as they expand. Because of that, installers often use longer galvanized roofing-style nails on vinyl, driven not quite tight.
Why you should not swap them on a roof
A siding nail's smaller head can pull through a shingle in wind and does not meet the IRC's 3/8 inch head minimum for asphalt shingles. Its extra length adds nothing except points poking through finished overhangs. Going the other way, a 1 1/4 inch roofing nail is too short to anchor siding into framing.
See roof anatomy explained and wind damage to roofs in Georgia.