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1¼ inch for new shingles on a bare half-inch deck, 1¾ inch over one existing layer, and 2 inch over two layers or a thick deck. The nail must reach at least 3/4 inch into the sheathing, or all the way through if the deck is thinner than that.
This guide explains how to choose the right roofing nail length and gauge for asphalt shingles. Standard rule: nail must penetrate at least 3/4 inch into the deck, or all the way through 3/4-inch or thinner sheathing. For 7/16" OSB single-layer install, use 1-1/4" galvanized nails; for an overlay, use 1-1/2" or 1-3/4" to reach the deck. Gauge is typically 11 or 12, with 3/8" head minimum. Stainless steel for coastal zones, hot-dipped galvanized everywhere else.
Roofing nail length is set by what the nail has to pass through before it reaches solid deck. The rule underneath every recommendation is the same: the nail must penetrate at least 3/4 inch into the sheathing, or all the way through if the sheathing is thinner than that.
| Situation | Nail length | Why |
|---|---|---|
| New shingles on a bare 1/2 in deck | 1¼ in | Passes the shingle and reaches 3/4 in into the deck |
| Over one existing layer | 1¾ in | Adds the thickness of the old shingle course |
| Over two layers, or a thick deck | 2 in | Same rule, more material above the deck |
| Thin or board sheathing under 3/4 in | Long enough to pass fully through | Full penetration replaces the 3/4 in rule |
| Ridge cap over a vent | 2 in or longer | The vent raises the cap off the deck |
Head diameter matters as well as length: 3/8 inch minimum, and 12 gauge shank is the usual specification. Undersized heads pull through the mat under wind load.
| Roof area | 4-nail pattern | Weight | 6-nail high-wind | Weight |
|---|---|---|---|---|
| 1,000 sq ft | 2,640 | 18.9 lb | 3,960 | 28.3 lb |
| 1,500 sq ft | 3,960 | 28.3 lb | 5,940 | 42.4 lb |
| 2,000 sq ft | 5,280 | 37.7 lb | 7,920 | 56.6 lb |
| 2,500 sq ft | 6,600 | 47.1 lb | 9,900 | 70.7 lb |
| 3,000 sq ft | 7,920 | 56.6 lb | 11,880 | 84.9 lb |
Weights assume about 140 nails to the pound at 1¼ inch. Longer nails weigh more each, so a 1¾ inch nail runs nearer 105 to the pound.
One and a quarter inch for new shingles on a half-inch deck, one and three quarter inch over one existing layer, and two inch over two layers or a thick deck. The nail must reach at least three quarters of an inch into the sheathing.
Twelve gauge shank with a head of at least three eighths of an inch is the usual specification. Undersized heads pull through the shingle mat under wind load.
Hot-dip galvanised is the general-purpose minimum. Stainless is required alongside copper and cedar, because dissimilar metals corrode each other, and is worth the cost in salt air.
No. Most manufacturers treat staples as voiding the wind warranty and many jurisdictions no longer permit them for shingle attachment.