When most building owners think about roofing damage, they picture wind, hail, or heavy rain. But one of the most destructive forces your commercial roof faces is something far more subtle — and it happens repeatedly, all winter long. It’s called the freeze-thaw cycle, and if your roof isn’t prepared for it, the damage can be extensive, costly, and surprisingly fast.
What Is the Freeze-Thaw Cycle?
The freeze-thaw cycle refers to the repeated process of water freezing and thawing as temperatures fluctuate above and below 32°F. During a typical winter in colder climates, this can happen dozens — sometimes hundreds — of times throughout the season. It sounds simple enough, but what this cycle does to roofing materials is anything but.
Why Water Is the Real Culprit
Water is unique in that it expands when it freezes — by about 9%. That expansion doesn’t sound like much, but when water has made its way into even the tiniest crack, seam, or membrane breach on your commercial roof, that expansion becomes a powerful force working against your building. When the temperature drops and that trapped moisture freezes, it pushes outward with significant pressure — widening existing cracks, separating seams, and compromising fasteners. When the temperature rises again and the ice thaws, the water migrates deeper into the newly enlarged opening. Then it freezes again. And the cycle repeats.
With each cycle, the damage compounds. What started as a hairline crack becomes a significant breach. What was a slightly loose seam becomes a gap wide enough to allow meaningful water infiltration.
How the Freeze-Thaw Cycle Damages Specific Roofing Systems
Different commercial roofing materials respond to freeze-thaw stress in different ways, but none are entirely immune.
Flat and low-slope roofing membranes — including TPO, EPDM, and modified bitumen systems — can become brittle in extreme cold, making them more prone to cracking when they experience foot traffic or movement. Seams are particularly vulnerable, as the repeated expansion and contraction stress the adhesive bonds and heat-welded connections that hold the system together.
Metal roofing and sheet metal components, like the systems we specialize in at American Roofing & Sheet Metal, expand and contract with temperature changes. When fasteners, flashing, or panel joints aren’t properly installed or maintained, that thermal movement can open pathways for water to enter — and once water gets underneath a metal panel and begins freezing, it can cause significant uplift and distortion over time.
Built-up roofing (BUR) systems can absorb moisture into the insulation layers beneath the membrane. Saturated insulation that freezes and thaws repeatedly loses its structural integrity and R-value, often requiring full replacement rather than repair.
Rooftop penetrations, flashings, and drains are among the highest-risk areas during the freeze-thaw season. Water tends to pool around these areas, and any failure in the flashing or sealant becomes an open invitation for cyclical freeze-thaw damage.
The Compounding Problem: Ice Dams and Ponding Water
Freeze-thaw damage doesn’t happen in isolation. It’s often made worse by two related problems — ice dams and ponding water. Ice dams form when heat escaping through the roof melts snow, which then refreezes at the colder eave or drain areas. This creates a ridge of ice that forces water back up under the roofing membrane. Ponding water, particularly common on flat commercial roofs, gives freeze-thaw cycles a much larger reservoir to work with — accelerating and amplifying the damage.
What Building Owners Can Do
The good news is that freeze-thaw damage is largely preventable with the right proactive approach. A professional inspection before and after winter is one of the most valuable investments you can make in your commercial roof. During a pre-winter inspection, a qualified roofing contractor can identify and seal vulnerable areas — cracks, failing seams, compromised flashings — before water ever has the chance to infiltrate. After winter, a post-season inspection helps catch damage early, before it has the chance to worsen through spring rains.
Proper drainage is equally critical. Ensuring that your roof drains, scuppers, and gutters are clear and functioning means water moves off your roof quickly rather than pooling and giving the freeze-thaw cycle more material to work with. Insulation and ventilation also play a role — a well-insulated, properly ventilated roof is less likely to develop the temperature differentials that cause ice dams.
Don’t Let Winter Win
Your commercial roof is one of the most significant investments protecting your building and everything inside it. The freeze-thaw cycle is relentless, but it doesn’t have to be catastrophic. At American Roofing & Sheet Metal, we’ve been protecting commercial buildings since 2004, and we understand exactly how winter weather interacts with the roofing systems in our region. Whether you’re due for a preventative inspection, dealing with existing damage, or planning for a roof replacement, our team is here to help you stay ahead of the season.
Contact us today to schedule your commercial roof inspection — before the freeze-thaw cycle does the work for you.
