Winter weather can be tough on any building—but for commercial properties with flat or low-slope roofs, the risks go beyond what you can see from the ground. Heavy snow, ice dams, and freeze–thaw cycles can all quietly compromise your roofing system’s structure and shorten its lifespan.
At Jewett Roofing, we work with building owners across Missouri and Illinois to prevent winter roof damage before it becomes a costly emergency. Here’s what you should know about how ice and snow impact your flat roof—and the warning signs to look for this season.
1. Snow Load: Weight That Adds Up Fast
It doesn’t take a record-breaking storm to overload a flat roof. Wet, compacted snow can weigh up to 20 pounds per cubic foot. That means even a few inches of accumulation can add several tons of weight to a large commercial roof.
Over time, this stress can lead to:
Sagging roof decks
Cracked seams or flashing
Compromised insulation or ponding water after melting
If snow buildup is consistent across multiple storms, it’s important to have a professional evaluate the load and safely remove excess accumulation before damage occurs.
2. Ice Dams: When Heat Escapes, Water Finds a Way
Ice dams form when heat from the building melts snow unevenly, allowing water to refreeze at roof edges and drains. The result: trapped water that seeps beneath the membrane or flashing.
This can cause:
Hidden moisture infiltration
Membrane blistering or separation
Interior leaks that appear days or weeks later
Proper insulation, air sealing, and routine inspections help minimize these risks by reducing heat loss and keeping surface temperatures consistent.
3. Freeze–Thaw Expansion: The Cycle That Breaks Roofs Down
The Midwest’s temperature swings—above freezing during the day, below at night—create constant expansion and contraction in roofing materials. EPDM, TPO, and modified bitumen systems each respond differently, but all experience stress at seams, terminations, and penetrations.
When moisture infiltrates and then refreezes, it expands, gradually widening cracks or lifting seams. Without intervention, this cycle can lead to leaks and premature membrane failure.
4. Warning Signs to Watch For
During winter, keep an eye out for:
New or worsening ponding water
Icicles forming along parapet walls or drains
Unusual creaks or deflection in the roof deck
Damp ceiling tiles or interior staining
These are early indicators that your roof is under stress—and that professional evaluation is needed.
5. How Preventive Maintenance Pays Off
Routine inspections, especially before and after major storms, help identify small issues before they turn into costly repairs. Cleaning drains, resealing flashings, and checking seams are simple steps that protect against heavy winter wear.
Jewett Roofing offers maintenance programs tailored for each season, ensuring your roof is monitored year-round and ready for whatever weather comes next.
The Bottom Line
Ice and snow don’t just threaten your building’s comfort—they threaten its structure. Proactive maintenance not only prevents damage but extends the life of your roofing system and protects your warranty.
Need help preparing for winter?
Contact Jewett Roofing today for a professional inspection or maintenance plan designed to protect your building through every freeze and thaw.
