How many roofing nails are needed per square?
Where the numbers come from
A square is 100 square feet of roof. The nail count depends on how many shingles it takes to cover that square, which depends on each shingle's size and exposure (the part left showing).
- 3-tab: a 12 by 36 inch shingle with 5 inches exposed covers 1.25 square feet, so about 80 shingles per square. Times four nails is 320.
- Architectural: many measure about 13 1/4 by 39 3/8 inches with a 5 5/8 inch exposure, covering a little over 1.5 square feet each, so about 65 shingles per square. Times four nails is about 260.
- Designer shingles vary widely in size and exposure, so check the bundle coverage on the wrapper and multiply.
Four nails or six
The International Residential Code sets four nails per strip shingle as the minimum. Manufacturers commonly require six for high wind installations, for slopes steeper than 21 in 12 like mansards, and to qualify for their higher wind warranties. Six nails adds about 50 percent to the count but costs very little compared with a blow-off repair.
What the per square number leaves out
These counts are field shingles only. Starter strips, drip edge, ridge and hip caps, and flashing add more, and you should allow 5 to 10 percent extra for waste and gun jams.
See how roofers measure a roof and wind damage to roofs in Georgia for why nailing matters.