London's climate is hard on roofs. Cold winters, constant freeze-thaw, heavy wet snow, spring rain and summer heat all work at the same weak points year after year. Here are the problems we see most on London commercial and residential roofs — what causes them, the warning signs, and what it takes to fix them before a small issue becomes an interior claim.
A properly built flat or low-slope roof drains standing water within about 48 hours. Water that lingers longer than that is ponding, and it's a red flag: it points to a drainage, slope, or clogged-drain problem, and standing water steadily breaks down the membrane, seams and adhesives underneath it. Left alone, ponding is one of the most common causes of a failed commercial roof. Tapered insulation or drain work usually solves it.
Most roof leaks don't start in the open field of the roof — they start where something goes through it. Rooftop HVAC units, skylights, vents, drains and pipe boots are the number-one leak points on a commercial roof, because the flashing and sealant around them takes the most movement and weathering. Re-flashing these penetrations is often a straightforward repair that heads off major water damage.
Flashing is the metal and membrane detailing at edges, walls, curbs and penetrations — and it's where a huge share of leaks begin. Freeze-thaw cycling lifts, cracks and pulls flashing away over time. If you see lifted metal, open laps, or staining on the wall or ceiling below a roof edge, the flashing is the first thing we check.
On single-ply and modified-bitumen roofs, foot traffic, dropped tools, wind-blown debris and freeze-thaw stress all cause punctures, blisters and split seams. A small puncture lets water into the insulation, where it spreads far beyond the visible hole. Catching these early during a maintenance visit is the difference between a patch and a tear-off.
This is a classic London winter problem. Heat escaping into a poorly ventilated attic melts the snow on the roof; that meltwater runs down to the cold eaves and refreezes, building a dam of ice that forces water back up under the shingles. The fix is at the source: proper attic insulation, balanced ventilation, and ice-and-water shield at the eaves — all of which a correctly built roof includes.
The mineral granules on asphalt shingles are their sunscreen. When you see bare, shiny patches, or granules collecting in the eavestrough, the shingles are aging and losing their UV protection — and they'll deteriorate faster from there. Hail and heavy storms accelerate it. Widespread granule loss is a sign the roof is heading toward replacement.
Shingles that curl at the edges, buckle into waves, or claw upward are telling you something — usually age, heat damage, or (again) poor attic ventilation cooking them from below. Curled and lifted shingles let wind and water underneath, so they're an early warning worth acting on before the next storm.
Southwestern Ontario gets real wind, and it finds any edge that isn't fastened down. On flat roofs that means lifted or torn membrane; on shingle roofs, missing or flipped shingles and torn flashing. Storm damage is often an insurance matter — photograph it and call us for a documented assessment.
The most expensive roof problem is the one you can't see. Water that got in through a small breach can saturate the insulation and travel under an intact-looking membrane, quietly rotting the roof and dropping its R-value. Infrared moisture scanning finds this wet insulation before you're paying to replace the whole roof.
The single most preventable roof problem. Leaves, debris and ice block drains, scuppers and eavestroughs, water backs up, and you're straight into ponding and leaks. Keeping drainage clear is the cheapest maintenance there is — and it's a standard part of our maintenance plans.
Small roof problems get expensive fast in London's freeze-thaw climate — a clogged drain becomes ponding, ponding becomes a failed seam, and a failed seam becomes soaked insulation. We'll come out, look at it honestly, and tell you whether it's a repair or a replacement — with a written, itemized quote. Serving London, Strathroy, St. Thomas, Woodstock and Middlesex County.