You can say a lot of things about roofs, and most of them might be true. But one thing that nobody can argue with is that roofs are tops. This statement can be taken in several ways. A roof does for the top of your home. It can also act like a "top" or lid for your home, keeping the rain out. Then, there's the third meaning, which is the one we happen to like the most: roofs are the best. (People say things are "tops" when they really like them.) Since we like roofs so much, we've decided to write about them, and you've discovered the blog where we do that.
Shingles with a wavy edge or a slightly lifted appearance may otherwise look like they are in good condition. There are a few things that can cause waviness, and they all need to be repaired before major damage occurs.
1. Popped Nails
One of the most common causes of wavy shingles is popped nails. Most asphalt shingles are held in place with two or more nails, which are placed in the top tabs. The upper row of shingles lays over these nails and tabs that are on the lower row. If nails pop out, they can push up the edge of the upper shingle and cause it to appear wavy from the ground. Temperature fluctuations are the main cause of popped nails. Popped nails can be replaced if there is no other damage to the shingles or roof decking.
2. Decaying Shingles
As shingles begin to wear out, they may lose their ability to repel water. Instead, the shingle begins to absorb moisture. The moisture causes the asphalt-infused felt or fiberglass of the shingle to warp and bend. The result is a wavy or cupped edge on the shingle. Eventually, water will make its way beneath these damaged shingles, which can result in more severe roof issues. Decaying shingles must be replaced. If you have a lot of decaying shingles, it may be time for a new roof.
3. Moss Humps
A roof in a shady, damp area can be prone to moss growth. Sometimes the moss grows beneath the shingles, lifting the edges and creating a wavy effect. If you clean the moss from the roof, some of these humps may remain because they are protected by the shingles that are covering them. A full roof cleaning, designed to kill the moss, is necessary. Your roofer can also install zinc strips beneath the shingles near the peak of your roof. The zinc isn't visible, but it will prevent moss from growing in the future.
4. Damaged Decking
The decking is the plywood sheathing beneath the shingles. Decking is designed to last for many decades, so it isn't usually replaced each time you re-shingle the roof. Over time, damage can cause the decking to absorb moisture. Since it is made of wood, the moisture will cause the decking to warp, and the result can be seen as the shingles nailed to it follow the warp and become wavy. Repair requires removing the damaged decking and replacing that section of the roof.
Contact a roofing repair service if you notice that your shingles look wavy or slightly lifted.