I noticed a few nail pops (lifted shingles) on your roof during your annual roofing inspection. My concern is that the lifted shingle may get blown up during a wind event and cause a roof leak.
A nail pop is a bump or raised shingle that leaves the roof susceptible to a water leak. However, there are multiple reasons for this condition.
Poorly nailed roof decking could be the culprit. Most builders use special wood similar to plywood called Oriented Strand Board (OSB). It’s primarily used for wall covering and roof decking. When the OSB isn’t attached securely, the day’s heat can cause the plywood to expand. At night it contracts. Over time, the decking can work the roofing nails loose, push the shingle upward, and cause a nail pop.
According to the International Residential Code (IRC) R905.2.5: “Fasteners for asphalt shingles shall be galvanized steel, stainless steel, aluminum or copper roofing nails, minimum 12-gage [0.105 inches (3 mm)] shank with a minimum 3/8-inch-diameter (9.5 mm) head, complying with ASTM F1667, of a length to penetrate through the roofing materials and not less than 3/4 inch
(19.1 mm) into the roof sheathing. The fasteners shall penetrate through the sheathing when the roof sheathing is less than 3/4 inch (19.1 mm) thick.”
The building code addresses the gauge of the nail. However, it doesn’t address the shank design or “type.”
Ring shank nails have small grooves cut around the shank. The grooves have twice the withdrawal resistance of smooth shank nails with the same diameter. Nail length and shank design can lead to nail pops.
Pneumatic nailers are another piece of the puzzle. Sometimes nails are driven in at an angle, or the gun isn’t set properly and over-drives or under-drives the nail. Some roofers use staples. Staple guns should be carefully set as they can easily tear through the shingle.
Shingles have a minimum required nailing pattern (as seen in the video above). If not followed, a poor nailing pattern can lead to shingle movement and result in a nail pop.
Soft Roof Decking
Another cause for a nail pop is subsurface fastening. The nails could slip and pull up if your roof is installed over thin or soft decking. That’s why monitoring your roof deck inside and outside the attic is a good idea.
Regular roof inspections help lower maintenance cost.
Repairing Nail Pops
Now that we’ve identified the most probable cause for the nail pop, we’re ready to repair it.
- ALLWAYS – Take Care
If you don’t have experience climbing and working on steep roof surfaces, leave this job to a professional roofing contractor. Use ladder safety rules. The following tips are for your information, and you take full responsibility when making this type of repair.
- Start by removing the nail.
Don’t just drive the roofing tack back down into the same hole. It’s best to lift it out, move over about an inch, and drive a ring shank nail into a new section of decking. Use care when lifting the shingle to prevent breaking the tab of the shingle.
- Use the right adhesive.
Use asphalt roofing cement that conforms to ASTM D4586. DAP® DYNAFLEX® 4586 Flexible Roof Asphalt Sealant is designed to seal leaks and repair loose shingles. It resists cracking and sagging and provides excellent adhesion, even on wet surfaces.
- A little dab will do on three-tab shingles.
Once the shingle is fastened, apply two cement spots about the size of a quarter under each tab on three-tab shingles. Use four spots of asphalt roofing cement on laminated shingles.
- Take care not to apply too much.
One spot may be placed one to two inches from each end of the tab and near the bottom, but not so close to the bottom that it is squeezed out from under the tab as the tab is pressed into the cement. Once the sun warms the roof, the shingle should lie down and blend with the other shingles.
Congratulations! You nailed it!