How Thermal Splitting of Asphalt Shingles Occurs

Untrained eyes won’t be able to tell the difference between cracking and thermal splitting of asphalt shingles. Professional roofers, however, can differentiate the two easily. Cracks are limited to the surface of the asphalt layer while thermal splits go through the entire shingle panel. In today’s post, Lankford Roofing & Construction LLC, your reliable roof replacement contractors, explain how thermal splitting can affect your asphalt shingles.

Understanding Roof Assembly

Roofing systems consist of two separate assemblies. The roof deck is formed by the roof sheathing attached to the framing members, such as rafters, roof trusses and ridges. The second assembly consists of asphalt shingles that are bonded to each other by adhesive strips. This may act as one big shingle if the adhesive bond is strong enough.

These roof assemblies may be joined together, but they are not considered as one structure. They consist of different materials that expand and contract at different rates. As the roof sheathing changes, it exerts forces on the shingles, which can lead to splitting or buckling of the roof panel. Get in touch with a contractor that offers roof replacement services if this happens.

How Thermal Splitting Happens

Thermal splitting is due to temperature-related expansion and contraction. This usually happens where the roof shingles connect to the joints in the underlying layer of shingles. It may also form a diagonal pattern up the roof, following the stair-up pattern of the offset joints made during installation.

Note, however, that splitting above underlying shingle layers occurs more often with fiberglass shingles than with organic asphalt shingles. This is due to a stronger adhesive bond of fiberglass shingles than their organic counterpart.

Thermal splitting, cracking or hail: how to tell them apart

They can look alike from the ground, but each leaves a different pattern.

• Thermal splits run straight through the shingle, often lined up with the joints of the course below, and can climb the slope in a stair-step pattern.
• Surface cracking stays in the top layer of asphalt and looks like fine crazing, usually on older shingles that have dried out in the sun.
• Hail damage is random: round soft spots or marks where granules were knocked off, spread across the roof and heaviest on the slope that faced the storm.

The difference matters because each is handled differently. Hail damage may be part of a storm claim. Thermal splitting and surface cracking are usually treated as wear or a product issue, so on a young roof the manufacturer’s warranty is the place to start.

Sealant can close a split for a while, but it is a stopgap. Have a roofer judge how widespread the splits are before choosing between a roof repair and a replacement.

Entrust your roof and window replacement to Lankford Roofing & Construction LLC, and boost your home’s energy efficiency, curb appeal and functionality. Call us today at (903) 465-7677 or (580) 920-1433 to learn more about our products and services. We serve residents of Sherman and Denison, TX.