What is the standard roofing nail length?
Short answer. The standard roofing nail length is 1 1/4 inches, which is what most crews load for asphalt shingles on 7/16 inch OSB or 1/2 inch plywood decking. It is long enough to pass through the shingle layers at the nailing line and meet the code rule of 3/4 inch into the deck or all the way through it.
Why 1 1/4 inch became the standard
Most homes have 7/16 to 5/8 inch decking, and a laminated shingle plus the course beneath it adds roughly 3/8 inch at the nailing line. A 1 1/4 inch nail clears that stack and passes through the deck with a margin, without being so long that it wastes material or pokes through finished overhangs. It is also the size most coil roofing nails are sold in, which keeps things simple on a job site.
The rest of a standard roofing kit
- 1 1/4 inch: field shingles, starter strip and drip edge.
- 1 3/4 to 2 inch: hip and ridge caps, and caps over ridge vents.
- 1 inch plastic cap nails: underlayment.
When standard is not enough
- Thick designer or impact rated shingles: many call for 1 1/2 inch.
- Roofing over an existing layer, where your building department allows it.
- Thick board decking with heavy shingles, where 1 1/4 inch may only just reach 3/4 inch of penetration.
- Ridge vents and high-profile caps, which follow the vent or cap maker's length.
Other roof types
Metal roofs use screws rather than standard roofing nails, and tile and slate use longer, corrosion resistant nails sized to their own rules. The 1 1/4 inch standard applies to asphalt shingles.
See roof anatomy explained and architectural vs 3-tab shingles.