Winter is one of the most challenging seasons for commercial roofs across Missouri and Illinois—but not always for the reasons building owners expect. In fact, some of the biggest winter roof failures stem not from extreme weather, but from misunderstandings about how flat and low-slope roofs behave when temperatures start to swing.
From hidden moisture to misunderstood heat loss, here are the most common myths we hear each winter—and the truth behind them.
Misconception #1: “We didn’t have leaks, so the roof is fine.”
A dry ceiling doesn’t mean a dry roof.
Moisture can enter a roofing system through a small crack or open seam, then become trapped between membrane layers or inside insulation. Because many buildings have concrete decks or batten insulation, this water can remain hidden for months.
We routinely find roofs that appear dry inside—but release gallons of water when we take a core sample.
Why this matters:
When temperatures drop, that trapped moisture expands as it freezes, prying apart seams, popping fasteners, and doing far more damage than a surface leak.
Misconception #2: “It hasn’t snowed, so nothing’s freezing.”
Snow isn’t the only threat.
Even on clear days, moisture from fog, mist, frost, or dew can seep into small openings. Once temperatures fall overnight, that moisture freezes—and the freeze–thaw cycle begins.
Winter damage isn’t tied to inches of snowfall. It’s tied to how often temperatures swing above and below freezing.
Misconception #3: “It’s too late in December to do anything.”
This is one of the most costly assumptions a building owner can make.
Winter may complicate roofing work, but it doesn’t stop it. Jewett Roofing continues repairing and servicing roofs throughout the season. We mechanically fasten, heat-weld membranes, and respond to emergencies as long as temps are safe for crews.
If a problem starts in December, you don’t have to “survive winter” and hope for the best.
Fixing small issues now prevents much larger ones during the next freeze–thaw cycle.
Misconception #4: “Drains only clog from leaves — not ice.”
Leaves are only half the story.
In winter, drains and gutters often freeze solid from the inside. Snow melts during warm spells, runs toward drains, and immediately turns to ice as temperatures drop again. When water has nowhere to go, it backs up beneath flashings or flows over the edge and into the foundation.
This freeze-ice-repeat cycle can create:
Ice dams
Heavy snow-and-ice buildup
Overloaded roof sections
Water flowing backward into the building
Clogged drains aren’t just a fall problem—they’re a winter problem with higher stakes.
Misconception #5: “Leaks only happen when it rains.”
Buildings often experience winter leaks even when the weather is completely dry.
One of the most common offenders? Condensation.
Large commercial buildings—especially those with significant heat loads—may run HVAC systems even on cold days. Those units produce condensation that drains across the roof surface. If that water encounters a small opening or freezes before draining properly, it can cause leaks that seem to appear out of nowhere.
We often investigate “mystery leaks” in winter only to find:
Active AC units dripping onto the roof
Heat exhaust producing condensation
Frozen drain lines backing up HVAC runoff
Moisture doesn’t need rainfall to become a roofing issue.
Misconception #6: “Insulation prevents winter leaks.”
Insulation helps with energy efficiency—but it doesn’t stop freeze–thaw damage.
Poorly insulated roofs may melt snow faster, leading building owners to believe that everything is functioning properly. In reality, the insulation simply disguises where heat escapes, and can even accelerate ice formation at colder roof edges.
Meanwhile, water trapped inside the roofing layers freezes, expands, and damages the system regardless of insulation thickness.
The Bottom Line: Winter Roof Problems Aren’t Always Obvious
Winter conditions create a perfect environment for hidden damage—especially on commercial flat roofs where water sits, freezes, and accumulates over time.
The real danger isn’t heavy snow.
It’s what you can’t see happening beneath the surface.
Understanding these misconceptions is the first step to preventing costly repairs in spring. The second step is getting ahead of the damage before freeze–thaw cycles magnify it.
At Jewett Roofing, our in-house crews, winter service teams, and emergency response technicians are equipped to diagnose issues even in harsh weather—and to stop leaks before they spread.
If you’re seeing early signs of trouble (or haven’t had your roof looked at since fall), we’re here to help before winter does its worst.
