Metal roofing is a popular choice for commercial buildings—and for good reason. It’s durable, long-lasting, and capable of handling decades of weather when installed correctly. But despite the promise of a “50-year roof,” metal systems are far from maintenance-free.
Winter, in particular, exposes vulnerabilities that building owners often overlook until leaks appear.
Understanding how metal roofs behave during temperature swings can help you protect your investment and avoid costly surprises.
Metal Roofs Move More Than You Think
One of the biggest misconceptions about metal roofing is that its strength equals stability. The reality is very different.
Metal expands in heat and contracts in cold.
Over a 50-foot run, a single panel can move roughly an inch as temperatures shift.
In the Midwest, where winter temperatures can swing from 0°F to 60°F in a single day, that movement happens constantly.
What this movement does:
Puts stress on fasteners
Pulls at seams
Causes popping noises (common on large metal buildings)
Stretches and compresses panel connections
Weakens sealants and mastics over time
Even a well-installed system isn’t immune to the physics of expansion and contraction.
Fasteners Loosen and Back Out During Winter
Most leak issues on metal roofs aren’t caused by the panels—they’re caused by the fasteners holding them down.
As the metal panels expand and shrink, fasteners slowly work their way out of the substrate. When this happens, they create small openings where:
Water can wick inside
Ice can expand and force gaps wider
Wind uplift becomes more likely
Seams can separate
In some cases, owners don’t notice anything until a warm day hits, the snow melts, and water shows up inside the building.
Seams, Mastic, and Ridge Caps Are High-Risk Areas
Even the best panels can’t protect a building if key details fail.
Chronic weak points include:
Panel seams that separate as panels move
Mastic at overlaps that breaks down with age or extreme temperature swings
Ridge caps—especially inexpensive or prefabricated versions used on large metal buildings
Tie-ins where one metal building connects to another
These areas are some of the most common sources of winter leaks.
Kevin noted this clearly: the metal itself might last 50 years, but the details holding it together rarely do.
The “50-Year Roof” Only Applies to the Panel—Not the System
This is one of the biggest surprises for building owners.
You may have been told your metal roof will last half a century. That’s true—but only for the panel itself. The rest of the system has a much shorter lifespan.
Typical lifespan expectations:
Metal panels: 40–50 years
Fasteners: 15–20 years (or sooner on large buildings)
Sealants and mastics: 5–10 years
Ridge caps and trims: highly variable based on material and installation
A metal roof is only as good as its weakest detail. Once fasteners or sealants begin to fail, the entire system becomes vulnerable—especially in winter.
When Should You Repair vs. Retrofit a Metal Roof?
Not every issue requires a full replacement. But knowing when repairs are enough—and when they’re just delaying the inevitable—can save owners significant money.
Repairs make sense when:
Only isolated fasteners are backing out
Small areas of mastic or sealant have failed
A ridge cap or tie-in is leaking
The building is showing early signs of movement stress
Common repair strategies include:
Refastening, replacing fasteners with oversized versions, adding coatings at seams, or repairing ridge caps.
A retrofit becomes the better option when:
Fasteners are failing across large areas
The roof has widespread seam separation
Panels are showing rust or coating wear
Multiple leaks return after repairs
The underlayment or insulation has become saturated
Movement has caused ongoing structural issues
A properly designed retrofit can give the roof decades of new life while improving insulation, drainage, and energy performance.
Metal Roofs Are Strong—But Not Maintenance-Free
Metal offers longevity, but it’s not immune to winter. Expansion, contraction, freeze-thaw cycles, and aging fasteners all add stress year after year.
The best thing a building owner can do?
Stay ahead of the movement.
Regular inspections, especially before and after winter, allow technicians to find:
Fasteners backing out
Broken mastic
Loose seams
Ridge cap deterioration
Early leaks at tie-ins
Hidden moisture inside insulation
A small fix now prevents an expensive retrofit later.
At Jewett Roofing, we work with metal systems every day—and we know exactly where winter causes trouble. Whether you need targeted repairs or are considering a retrofit, our team can help you understand the condition of your metal roof and plan the best path forward.
