Roof Damage Caused by the Freeze-Thaw Cycle

March 12, 2019

As winter turns into spring, the inevitable cycle of warming and cooling can wreak havoc on commercial roofs. We asked J.J. Longerbeam, Vice President Service, D. C. Taylor Co., Cedar Rapids, IA, what kind of destruction facility professionals can expect and which roofs are most susceptible.

What effect does thermal shock (i.e. dramatic swings in temperature) have on commercial roof systems?
Thermal shock can have minimal or major effects on commercial roof systems. A newer commercial roof is extremely elastic and would most likely have minimal impact from the expansion and contraction of the roof membrane during a dramatic swing in temperature. Whereas an aged roof with membrane at the end of (or has exceeded) its intended life cycle, would be more susceptible to major effects due to thermal shock. An older roof membrane is not nearly as flexible and cannot perform under the extreme conditions and drastic temperature changes.

What damage does contraction and expansion cause?
Roof damage resulting from contraction and expansion can include, but is not limited to:

Are certain roof systems (like metal) less susceptible to damage from freeze-thaw cycles?
No particular type of roof system is less or more susceptible than another. A metal roof, for example, goes through extreme contraction and expansion throughout the season change as well as throughout its life span. Like any other roof system, when a metal roof is at the end of (or has exceeded) its life cycle, one may see horizontal and/or vertical seams open up, as well as fasteners backing out and/or missing all together.

Is this damage usually covered by the roof system manufacturer’s warranty?
Damage due to thermal shock may or may not be covered under warranty. Your roofing contractor can send pictures and the findings to the manufacturer’s representative to check, as the manufacturer is the warranty provider (not the roofing contractor). In my experience, damage to the roof from thermal shock is not typically covered under a manufacturer’s warranty because the roof is older and the warranty has expired.

How does freezing-thawing exacerbate an existing leak?
Freezing and thawing can have a dramatic impact on a present leak. Here’s an example: It may be 10 degrees outside (well below freezing). A location receives 6 to 8 inches of snow. The snow is insulating the roof and causing melting snow above the roof membrane. If there was a present leak (e.g. damage, like cuts or punctures) to the roof membrane the leak will only be worse, either a constant or steady drip.

What can building owners or facility managers do to prevent damage from thermal shock?
A routine preventive roof maintenance program is a facility manager’s or building owner’s best protection against damage from thermal shock. Routine inspections and maintenance will identify defects before they become a major repair or replacement and also determine when a roof is at the end of (or exceeded) its life. A roof maintenance program should cost pennies per square foot, an emergency repair most likely will cost hundreds of dollars per square foot.