Flashing is one of the most important—and most overlooked—components in any flat roof system. In Toronto, where roofs face snow, wind, rain, and extreme temperature swings, properly installed flashing is essential to prevent leaks. When flashing fails, water infiltration isn’t far behind, making flashing repair or replacement a key part of any flat roof repair plan.
Flashing serves as a waterproof barrier at connection points where the roofing membrane meets vertical surfaces or penetrations, such as walls, chimneys, vents, skylights, or HVAC units. On flat roofs, these areas are especially vulnerable, since water tends to sit longer and drain more slowly compared to sloped systems. Without flashing—or with flashing that’s cracked, corroded, or poorly sealed—water will penetrate the membrane and damage the insulation and roof deck below.
One of the most common issues flat roof technicians see in Toronto is lifting or separated flashing. This often occurs due to freeze-thaw cycles, which expand and contract materials. In winter, water may freeze behind loosened flashing, forcing it further out of place and creating entry points for water. Over time, the damage spreads, affecting adjacent membrane seams and allowing larger leaks to develop.
Another common problem is inadequate or outdated flashing materials. Older buildings in Toronto may still have galvanized metal flashing, which corrodes over time. Modern systems use longer-lasting aluminum or reinforced membrane flashing that performs better under thermal stress.
Because flashing is such a common failure point, it should be inspected at least twice per year—especially in spring and fall. Key signs of damage include rust, separation, dried-out sealant, and sagging at the base of rooftop walls or around penetrations. These indicators suggest the flashing is no longer doing its job and that water is likely entering the system undetected.
In many cases, damaged flashing can be resealed or replaced without redoing the entire roof. A professional flat roof repair crew can cut out and replace flashing sections, reinforce seals, and integrate the new flashing into your existing membrane. If the surrounding membrane is also compromised, it may be necessary to rebuild that portion of the roof to ensure watertight integrity.
If your flat roof hasn’t had its flashing inspected recently—or if you’ve noticed signs of water near rooftop penetrations—it’s time to act. For expert flashing work and full-service flat roof repair, contact Flat Roof Repair Toronto. Their team offers comprehensive flat roof flashing repair and fast, durable flat roof repair to protect your home or commercial building.
