Proper nailing is essential to the performance of roof shingles

Bitumen roof shingles may be one of the simplest roofing materials to install, but nevertheless they also require specialized and exact rules on how to be fastened. It is important to apply roofing nails in the right quantity and location to securely lock a shingle into its place. Accurate nailing affects the performance of roofing shingles and it is also required by the International Building Code.

The correct penetration of the wooden roof deck looks like this.

General fastening rules

Proper fastening is essential to a good roof performance. To ensure proper nailing during the shingle application:

  • Use the correct type, size and grade of nail as is specified in the application instruction.
  • Use corrosion resistant nails.
  • Use the recommended number of nails per shingle.
  • Position the nails according to the shingle specifications.
  • Align the shingles properly before nailing to avoid exposing nails in the course below.
  • Drive the nails straight and flat with the shingle surface.
  • Do not break the shingle surface with the nail head.
  • Do not drive nails into knotholes or cracks in the roof deck.
  • Repair incorrect nailing immediately.
  • Always nail the shingle from one side to the other, so the shingle stays flat on the roof.
  • Follow the application instructions concerning special nailing procedures for steep slopes, high wind areas, and any special requirements.
  • Comply with local building codes.

If a nail does not penetrate the deck properly and cannot be tapped down to be properly driven, remove the nail, repair the hole in the shingle with bituminous mastic and place another nail nearby. If necessary, replace the entire shingle.

Improper shingle nailing

One of the most common defects with asphalt shingles is improper nailing. IKO and other manufacturers of asphalt shingles give specific instructions on how to fasten shingles, and they’re all pretty much the same. Unfortunately, some roofers don’t seem to pay a lot of attention to these instructions. That is why we want to highlight the two most common nailing defects with shingles: overdriven nails and improperly located nails.

Overdriven nails

Many roofers use pneumatic nail guns to nail down the shingles.  When the pressure is set too high, the nails simply get driven into the shingles too far.  When the nails are overdriven, the heads of the nails punch right through the mat of the shingle.  This voids the shingle manufacturer’s warranty and greatly increases the potential for shingles to come loose and be blown off, possibly in full shingle sheets.

Remember: Only properly driven and applied roofing nails are utilized as a preferred fixing system for asphalt roof shingles!