The shingles on your home's roof are important for keeping water from leaking into your house and causing damage. However, just as important are the sheets of plywood that shape and support the shingles. Without the underlayment, the roof would collapse. Especially if your roof is getting on in years, the underlayment could be deteriorating. If you suspect that this could be the case, look for the following signs.
1. Shingles Have Started to Buckle up and Appear Warped
While looking at your roof to determine whether the underlayment has started to deteriorate, examine the condition of the shingles. Since the plywood supports them, rotting, breakage, or shifting of the underlayment can affect the appearance of the shingles.
While looking at the shingles, take note of any pieces that look as though they are buckling up away from the plywood, giving them a warped appearance. If the underlayment has shifted or is starting to rot, some of the shingles will no longer have a solid surface on which to adhere, causing the middle to raise up.
Also, shifting can force the ends of the shingles together, creating the warpage. These raised areas will allow water to travel underneath the shingles and onto the underlayment, which will then add to the deterioration of the wood.
2. Roof Has Sections That Appear Concaved
After examining the shingles, step back away from your house so that you can get an overall picture of the shape of the roof. Ideally, each side should appear fairly even with no dips or hills noted in its shape.
However, if the underlayment is severely deteriorated, it will start to bow under the weight of the shingles and moisture. You will see concaved sections in your roof when this happens.
If you are having problems with deciding whether the roof has become concaved, wait to look at the roof either during or after a moderately heavy day of rain. If water ponds on your roof, this helps you pinpoint the concaved areas. You will need to have the issue looked at by a professional because the water collections will only add to the problem.
If your roof is showing signs that indicate the underlayment has sustained damage and/or is deteriorating, it is time to consider having your roof replaced since the supporting structures of the shingles will not be able to support the shingles much longer. Contact a roofing company to have them inspect your roof and confirm the issue as well as discuss your options for either repairing the damaged areas or replacing the entire roof.