The number of nails required per square (100 sq ft) varies by roofing material: Asphalt shingles typically require 320-480 nails per square (4-6 nails per shingle), wood shingles need about 180-250 nails per square, metal roofing uses 70-150 specialized fasteners per square, clay/concrete tiles need approximately 250-350 nails per square, and slate roofing requires about 300-400 nails per square. Always check your manufacturer’s specifications, as some architectural or specialty shingles may have different requirements. Also, local building codes in high-wind areas may require additional fasteners beyond the manufacturer’s minimum specifications.

The ideal nail length depends on your roofing material and installation method. For asphalt shingles, use 1¼” nails for new roof installations and 1½” nails when installing over existing shingles. Wood shingles typically require 1¾” to 2″ nails. Clay or concrete tiles generally need 2″ to 2½” nails. Slate roofing usually requires 1½” to 2″ slating nails. The most important factor is ensuring that nails penetrate through the roofing material and at least ¾” into solid wood decking or completely through plywood/OSB decking. Additionally, all roofing nails should have large heads (at least ⅜” diameter) to provide adequate holding power and prevent pull-through.

To calculate the weight of roofing nails needed, first determine the total number of nails required for your project using our calculator. Then, convert that quantity to weight using the following approximation: standard 1¼” roofing nails come about 140-150 nails per pound, 1½” nails average 120-130 per pound, and 2″ nails average 90-100 per pound. For example, if your project requires 4,500 nails using 1¼” nails, you would need approximately 30-32 pounds of nails (4,500 ÷ 145 = 31 pounds). Always round up to the nearest package size when purchasing. For larger projects, consider buying in bulk (5, 10, or 25-pound boxes) for cost savings.

Both methods have advantages when installed correctly. Hand nailing provides better control over nail placement and driving depth, reducing the risk of overdriving and damaging shingles. Many professional roofers prefer hand nailing for premium materials like slate and wood shingles. Nail guns significantly increase installation speed, making them ideal for larger projects and professional crews. However, pneumatic nailers require careful pressure adjustment to prevent overdriving nails. For DIYers, hand nailing is often recommended for smaller projects and premium materials, while nail guns can be rented for larger asphalt shingle projects. Regardless of method, proper nail placement and driving technique are essential for roof durability and warranty compliance.

Using too few nails can have serious consequences for your roof’s performance and longevity. Insufficient nailing may void your roofing material warranty, as most manufacturers specify minimum nailing requirements. More importantly, inadequate fastening significantly reduces wind resistance, potentially leading to shingle lift, damage, or complete blow-off during storms. Even in non-storm conditions, insufficiently fastened roofing materials may shift, curl, or buckle over time, creating water entry points that lead to leaks and structural damage. Additionally, materials not properly secured are more likely to develop gaps that admit water and debris. While using too few nails might save money initially, the potential for premature roof failure and costly repairs or replacement far outweighs these minor savings.

Reusing old roofing nails is strongly discouraged by roofing professionals and material manufacturers for several important reasons. Used nails typically have reduced structural integrity from the original installation and removal process, which compromises their holding power. Most used nails develop some degree of rust or corrosion, even if not visible to the naked eye, which can accelerate after reinstallation. The time and labor required to collect, sort, and straighten used nails far exceeds the modest cost savings, especially considering the risk to your roof’s integrity. Additionally, using recycled nails will likely void any manufacturer warranties on your new roofing materials. For a secure installation that will protect your home for decades, always use new nails of the appropriate type, size, and quantity for your specific roofing material.