Way Up on the Roof

If you notice deep cracks running all the way through your shingles, it's likely that the problem is due to thermal splitting rather than impact from hail or a tree branch. Thermal splitting is a fairly common problem in low-quality composition shingles since they use a very thin fiberglass mat to hold the shingle together. Thermal expansion and contraction can pull the mat apart, causing a deep split in the shingle. To understand why this problem happens and why you need to have it fixed, read on to learn more about thermal splitting in composition shingles.

What Causes Thermal Splitting in Composition Shingles?

Thermal splitting is caused by repeated thermal expansion and contraction tearing the fiberglass substrate of a shingle apart. When composition shingles are manufactured, the sides are coated with a heat-activated adhesive. When they're installed on a roof, sunlight will cause the adhesive to cure and bond adjacent shingles together. This provides added wind resistance since adhered shingles are less likely to be lifted up by the wind.

However, a strong adhesive can cause thermal splitting in shingles when the fiberglass substrate is too thin. When temperatures drop rapidly, the shingles on your roof will begin to contract. Since a shingle is glued to the shingles around it, this contraction can pull a shingle apart when the adhesive is stronger than the fiberglass mat holding the shingle together. This results in a deep crack that extends all the way through the entire shingle.

Is Thermal Splitting a Serious Problem?

Since the crack extends through the entire shingle, thermal splitting makes your roof more likely to leak. It also increases the chance that your roof will undergo further damage. Water can pool in the crack, and standing water can rapidly damage the shingles on your roof and the waterproof roofing underlayment that stops water from entering your attic.

The deep crack also allows sunlight to reach the roofing underlayment, which will cause it to degrade. If you notice a problem with thermal splitting on your roof, it's a good idea to have it repaired as soon as possible in order to avoid more extensive roof damage.

How Do You Repair a Roof With Thermal Splitting Damage?

You can prevent thermal splitting damage from causing your roof to leak by replacing all of the affected shingles. A roof repair company in your area can do this quickly and inexpensively.

Unfortunately, it's likely that the problem will return—if the composition shingles used on your roof are susceptible to thermal splitting once, they're always at risk of splitting if the temperature drops suddenly. The only true cure for a recurring thermal splitting problem is to replace the entire roof with shingles that have a thicker fiberglass mat since it's better able to withstand the forces that pull at it.

If you notice that some shingles on your roof are experiencing thermal splitting, call a roof repair service in your area and have them inspected. You'll need to have the shingles replaced, and you may need to replace nearby shingles that have been damaged by standing water. While replacing the shingles isn't a permanent fix, it's the best course of action to reduce the likelihood of roof leaks and further damage to your home's roof.

For more info, contact a roofer.