How long should ridge vent nails be?
Short answer. Ridge vent nails must be long enough to pass through the cap shingle and the vent and still penetrate at least 3/4 inch into the wood deck or go fully through it, which is the standard in manufacturer instructions. In practice that usually means nails from about 1 3/4 inches up to 3 inches, depending on how thick the vent and cap shingles are; the vent's instruction sheet lists the minimum.
Do the stack up
Add the thickness of the cap shingle, the vent at the nailing point, and the deck, then make sure the nail reaches 3/4 inch into the deck or pokes through. On a typical 7/16 inch OSB deck, the nail has to go all the way through, since the deck is thinner than 3/4 inch. One manufacturer's spec also accepts about 1/8 inch through rated sheathing.
- Thin rolled vents with standard caps: often 1 3/4 to 2 inch nails.
- Thick rigid vents with high profile caps: often 2 1/2 to 3 inch nails.
Nail type
- Galvanized or other corrosion resistant roofing nails.
- Ring shank nails hold better where the manufacturer recommends them.
- Heads at least 3/8 inch, sized like standard roofing nails, so they do not pull through.
Why it matters
- Too short: cap shingles and vent lift in wind, end caps peel back and water gets in at the ridge. Short ridge nails are one of the most common causes of ridge blow offs after Georgia thunderstorms.
- Overdriven: nails crushed into a vent flatten it, cut airflow and dimple the ridge line.
- Wrong spot: nails must go through the vent's marked nailing zone so they hit solid deck, not the open slot.
Look up from the attic: properly nailed ridges show nail tips through the deck along both sides of the slot. See wind damage to roofs in Georgia and ridge vent vs box vents.