Thermal Shock

According to the roofing authorities, thermal shock is one of the leading causes of premature roof failure. What is thermal shock? How does it affect a roof? What can be done?

Thermal shock is a phenomenon that occurs when the forces of hot & cold meet in a roof system.

Everything contracts and expands as it heats and cools. Each component of a building (wood, concrete, steel, asphalt, etc.) has its own contraction and expansion rate.

Roof Effects

Not only do all the components contract and expand during the hot/cold, day/night, winter/summer cycles, but the potential problem is further amplified by the fact that many times two or more components are joined together in a single system, and those components have vastly different contraction and expansion rates. As an example, take a common roof system of a concrete deck, steel roof edges (gravel stop) and asphalt roof membranes. You can imagine the different contraction / expansion rates occurring, while the different materials are attempting to grip each other. There are three components contracting and expanding, but to differing degrees.

The potential exists from the time the roof is first installed. However, since the new roof adhesive (asphalt or tar) and membranes (felt) contains oils and saturants, the roof is able to flex (contract and expand) without apparent harm. As the roof system is subject to the ravages of heat, and the sun’s rays, the oils and saturants are leached and baked out. The system then becomes dry and brittle. The flexing that originally did little harm now destroys the roof. Cracks and splits happen, and the roof has to be replaced.

Take the time to know about better asphalt based products as well as the new single ply systems. Also educate yourself in the more advanced technological roof recovery systems that are available.