Flat roofs in Ontario take a beating from freeze-thaw cycles. What looks fine now might already be wearing thin. That’s why inspections in spring and fall matter – they catch silent damage before it spreads.
Start with drainage. Are the scuppers clear? Any standing water after rain? Check membrane seams, flashing, and rooftop equipment edges. Small bubbles or lifted corners often point to trapped moisture. Quick checks now prevent major costs later. And with aging roofs, even one early catch can delay full replacement by years.
Membrane Condition and Surface Integrity
Start with the obvious – the surface. Cracking, blistering, bubbling, and discoloration are all signs of trouble. Some amount of wear is normal over time, but once the membrane starts to curl or develop alligatoring (that cracked leather look), it’s more than cosmetic. It means UV and temperature have weakened the material. Left alone, these areas become entry points for water.
If you have a modified bitumen system, look for signs of granule loss. If it’s a TPO or EPDM roof, focus on seam integrity and pulling at edges. At this stage, your priority should be documenting what’s stable and what’s beginning to degrade. Our flat roof inspection service goes deeper than a surface scan – we check bonding, test adhesion, and mark out areas where deterioration is accelerating.
In one case, we caught early-stage seam separation on a 12-year-old EPDM roof in Vaughan. Just a half-inch gap, but right near a drain. Two weeks later, during a heavy rain, it would have turned into a leak. That small find saved the client thousands in interior repairs.
Drainage and Ponding Issues
Flat roofs don’t drain on gravity alone. Every drain, scupper, and downspout has to stay open and functional year-round. Over time, debris builds up, and aging insulation can cause minor depressions in the roof. These dips hold water longer after rain – and that’s where leaks usually begin.
Walk the roof after rainfall if you can. Look for standing water more than 48 hours after the weather clears. Even if the surface looks okay, ponding slowly breaks down seams and allows water to penetrate insulation layers. Left long enough, it turns a surface patch into a complete roof replacement.
We also check internal drainage systems. Roofs that rely on interior piping can hide issues until it’s too late. One industrial client in Mississauga had no exterior signs of trouble, but their roof drain had backed up into the insulation layers below. Mold had spread through 40 feet of decking before it became visible indoors.
Flashing, Edges, and Wall Intersections
Flashing fails quietly. It might look okay from a distance – but cracked caulking, lifted metal, or dried-out sealant can break the waterproof barrier in ways that go unnoticed until it rains hard. On aging roofs, the seal between membrane and flashing is often the first point to fail. Especially where the roof meets vertical walls, skylights, curbs, or old parapets.
We inspect all perimeter flashing, and we usually re-seal trouble areas on the spot during scheduled maintenance visits. This kind of detail work is what prevents expensive leak calls later. And if the flashing itself is corroded, it’s often worth upgrading to a modern alternative that better integrates with your current membrane type.
We’ve replaced failing 20-year-old flashing on properties that still had a functional roof membrane – but water had been sneaking in at the wall joints. Flashing failure caused more damage than the roof itself.
Mechanical Penetrations and Rooftop Equipment
Most aging commercial flat roofs have at least a few rooftop penetrations – HVAC units, gas lines, plumbing vents, or even abandoned structures that no one’s touched in years. These are risk zones. The sealant around them breaks down faster than the main membrane, and vibrations from active equipment speed up that wear.
We recommend checking the base of every unit and confirming that pitch pans, boots, or curbs are still sealed. A minor gap around a vent pipe can cause leaks that take weeks to trace from the inside. If you’ve had new mechanical equipment installed in the past 3 years, it’s worth booking a maintenance inspection just to verify nothing was damaged during install. We’ve seen installers drive screws through waterproof layers without realizing it.
Also – clear any debris. Ballast rocks, loose screws, or sealant tubes left behind can puncture the membrane over time, especially during freeze-thaw movement. Clean roof = longer lifespan. It’s that simple.
Signs of Subsurface Moisture or Structural Stress
This is the part you won’t spot unless you’re really looking for it – moisture inside the insulation or signs that the roof deck is beginning to shift. We use infrared cameras and core cuts (when necessary) to detect trapped water beneath the surface. If the insulation is wet, it loses all R-value and starts breaking down the deck below.
Sagging, soft spots, or a bouncy feeling when walking the roof? Those are red flags. Same with ceiling stains indoors, even if the roof looks fine from above. These are the invisible signs of failure that inspections are meant to catch.
If your roof is nearing 15+ years old and you’ve never had a thermal scan or core sample done, we strongly suggest it. It’s not invasive, and it gives you a real picture of what’s happening under the surface.
Final Thoughts – Aging Roofs Can Still Perform if Watched Closely
Aging doesn’t mean failing. We’ve seen 20-year-old roofs still doing their job beautifully – just because the owner kept up with inspections and maintenance. But we’ve also seen 10-year-old roofs fail completely from neglect. The difference comes down to attention.
Whether you manage a school, warehouse, medical facility, or mixed-use building, knowing your roof’s condition puts you in control. It gives you time to plan – not just react. And that’s what inspections are really about. Control, not surprises.
Want to stay ahead of issues before they turn into leaks? Book your flat roof inspection now. We’ll walk it with you, explain what matters, and help you build a smart plan that protects what’s underneath.