Why Are Your Shingles Wavy and Partially Lifted?

When you look up at your roof, do some of the shingles seem to be wavy along the edges? Perhaps some of the edges seem to be lifted off the roof surface. Often, this does not indicate an issue with the shingles themselves, but rather with the nails that are supposed to hold the shingles in place.

When a roof is shingled, each layer of shingles is positioned over the nails in the layer of shingles beneath it. If one of these nails pops up, the shingle on top of it will buckle or rise, too, which creates a wavy look.

Popped-up roofing nails are not something you want to ignore. Keep reading for a closer look at this problem and its solutions.

Why Do Roofing Nails Pop?

Nail pops can be caused either by environmental conditions, construction mistakes, or both.

Sometimes pops occur if a roofer uses nails that are too short. A short nail cannot fully anchor the shingle to the roof’s underlayment, so over time, the nail rises. This is often seen on DIY roofs; homeowners may attempt to save money with shorter nails — a mistake that comes back to bite them later on when the nails pop. Nails that are driven in at an angle are also likely to pop.

Nails sometimes pop if the roof decking is too worn or rotten to support the nails. If you’ve had untreated leaks in your roof for a while, the wood underlayment may now be beginning to rot, leaving it weak and soft. 

Fluctuations in temperature and humidity can also contribute to nail pops. Even in a properly shingled roof, a very hot and humid summer may cause a few nails to rise. As the roof ages, this problem will become more prevalent.

What Are Some Other Signs of Popped Nails?

Wavy, lifted shingles are not the only sign of raised roofing nails. If you cannot see all of your roof from the ground, you should keep an eye out for these additional signs that your nails are not holding well:

  • Water spots on your ceilings due to small leaks
  • Bubbling under the interior paint after a heavy rainstorm
  • Water stains on your roof rafters
  • A musty smell in the attic or on your top floor

Homeowners often assume that roof leaks must be due to missing shingles. But if your roof has been leaking and all of the shingles are still in place, popped-up nails are a likely culprit. Note that the water won’t always come in right where the popped nail is located. It may dribble down a beam or trickle down the underlayment a ways before entering your attic.

Why Are Popped Nails a Concern?

Popped nails are a concern for two reasons. First, a popped nail will eventually lead to a water leak if left unaddressed. Water can seep in through the roof in the space immediately surrounding the raised nail, especially after a heavy storm with wind-driven rain that gets under the edges of the lifted shingles.

Second, popped nails are worrisome because they suggest that your underlayment may be damaged or your roof may be poorly shingled. If your roof is older and you’re just starting to notice a couple of nail pops, you do not need to be overly worried. On the other hand, if you recently had the roof replaced and numerous shingles already look wavy due to lifted nails, this is a red flag.

What Should You Do About Popped Nails?

Some homeowners attempt to fix their own popped nails by simply pounding them back in. This is an okay short-term fix if you’ll have the roof replaced in a few months’ time. However, if your next roof replacement is any further away than that, you really need to remove the offending nails and replace them. Pounding a popped nail back in still leaves the nail loose; water can still seep in around it, and the nail will probably pop up again.

The proper way to deal with a popped nail is to lift the shingle on top of the nail, and then pry the popped nail out. Then, you pound in a new roofing nail about an inch above the popped nail. Finally, you plug the hole from the old nail with some roofing cement. 

If you’re confident working at heights and you only have a couple of popped nails, you might be able to handle this project yourself.

However, you need to consider several factors such as which size nails to use, where to place the nail for the most stability, and whether or not the underlayment is actually strong enough to nail to. (If it’s not, you’ll need to have the whole roof replaced.) For these reasons, you’re usually best off calling a professional to take care of your popped roofing nails.

If your roof is beginning to develop raised nails or any other signs of wear, contact The Roof Doctor. Our expert roofers will inspect your roof, make recommendations, and get you on the schedule for roof repairs or a replacement.

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