While looking at your roof, you may feel that something does not look quite right with its shape. However, if the shingles still appear to be in good condition, you may feel that the structure is still sound.
However, even if the shingles on the top layer of the roof are intact, there could be an issue underneath this layer with the wood underlayment, which forms the sturdy base for the roof. Below are a couple of signs that this crucial part of your roofing system is damaged and needs to be looked at by a professional.
1. Pushed-Up Shingles That Appear in Straight Lines
The first sign that there are issues with the roof's underlayment can be easy to miss unless you look closely at the shingles from the edge. While looking at the flat surface of the shingles, you may see what appear to be pushed-up areas that form small ridges where you know there should not be any.
Because the underlayment is made from plywood, the wood sheets will expand and contract when they are exposed to moisture and temperature changes. Over time, the wood may expand to the point that the edges of the sheets will start to overlap.
When the edges overlap, small gaps will form between the sheets, and the shingles will be pushed up and minuscule gaps will develop between them. This scenario can allow water to leak in under the shingles, through the sheets of plywood, and eventually into your home.
2. Otherwise-Flat Areas of Shingles Appear to Have Hills and Valleys
While looking for ridgelines on the surface of your roof, also pay attention to how flat the shingles are laying. If the surface seems wavy, with hills and valleys forming, this is another sign that the underlayment is damaged.
If the plywood starts to deteriorate, it will no longer be able to hold up the weight of the shingles and maintain the shape of the roof. Not only will this lead to future leaks if left unrepaired, but it could eventually cause a partial collapse of the roof.
If your shingles seem to have ridgelines where they should not or hills and valleys start appearing on your roof, the roof's underlayment may have shifted from temperature changes, or the wood's deterioration has made it unable to withstand the weight of the shingles. If you suspect that this is the case, contact a roofing contractor near you to schedule a time for them to inspect your roof to determine what is causing the issues with the underlayment so that they can be fixed.