Roof Flashing Repair and Commercial Cladding
Parapet and wall detailing on flat roofs, plus metal siding and cladding for commercial and industrial buildings.
Flashing is the metal and membrane detailing that seals a flat roof where it meets a wall, a parapet, a curb or a penetration, and it is where most Toronto commercial roofs leak first. NorthCan Roofing repairs and rebuilds flashings and installs commercial metal cladding and siding across the GTA. Call 416-456-0777.
Why does flashing fail before the roof does?
Because the field of a roof is a flat sheet doing one job, while a flashing is a junction between two materials that move differently, in the coldest and most exposed part of the assembly.
- Thermal movement. Metal expands and contracts along its length far more than the wall it is fixed to. Long runs of cap flashing without properly designed joints buckle, open at the laps and pull their fasteners.
- Ice damming at parapets. Meltwater runs to the cold perimeter, refreezes, and backs up behind the ice until it finds a way behind the cap flashing or over the membrane turn-up. This is the single most common Toronto flat roof leak.
- Freeze-thaw cycling. Water in a lap or a sealant joint expands each time it freezes and opens the defect a little further.
- Sealant used as a design element. Sealant is a secondary line of defence with a limited service life. Where it is the only thing keeping water out, the detail is already failing.
- Height. A membrane turn-up that is too low, often because a re-roof added insulation without re-detailing the wall, lets water over the head of the flashing during a heavy rain or a snow melt.
- Masonry behind it. Failed mortar joints, spalled brick and a missing or blocked through-wall flashing put water behind a perfectly good roof detail.
What flashing work do you carry out?
Flashing is a trade in itself, and on most repair jobs it is where the actual work is.
- Base flashing. The membrane turn-up at walls, parapets and curbs, installed over a cant strip so the membrane makes a supported change of direction rather than a sharp bend, and carried to an adequate height above the finished roof surface.
- Cap flashing and coping. Formed metal over the head of the parapet, with a slope back to the roof, drip edges to throw water clear of the wall face, cleats and expansion joints in the run rather than rigid butt joints.
- Counter flashing and reglets. Metal set into a saw-cut reglet or a masonry joint, lapping over the base flashing so water is shed rather than trapped.
- Curb flashing. At rooftop units, hatches, skylights and equipment supports, with proper curb heights so the membrane terminates above splash and drift level. See skylight installation.
- Penetrations. Pitch pockets rebuilt or replaced with proper flashed sleeves, gas lines and conduit lifted onto engineered supports rather than resting on the membrane, and vent and stack flashings replaced.
- Drains and scuppers. Drain flashings reset under the clamping ring, sumps re-formed, and scupper boxes lined with formed metal rather than sealed with mastic.
- Edge metal and gravel stops, refastened or replaced, because the perimeter is where wind uplift begins.
Flashing repairs are quoted from a site assessment and documented in the same way as our flat roof repairs.
What commercial siding and cladding do you install?
The second half of this trade is the wall. Roofing and cladding meet at the same junctions, and a contractor who does both can detail that junction properly instead of leaving it to the next trade.
- Metal wall panels. Concealed-fastener architectural panels for street-facing elevations, and exposed-fastener profiles for industrial walls, screens and service enclosures.
- Insulated metal panels, where the wall assembly combines the exterior skin, the insulation and the interior liner in one panel, common on cold storage and industrial buildings.
- Soffit, fascia and trim, formed to match the roof metal in profile and finish.
- Parapet and mansard cladding, including the transitions where a sloped element meets the low-slope roof.
- Mechanical screens and enclosures around rooftop plant, which are structural elements that carry wind and snow drift and need to be fixed accordingly.
- Repairs and panel replacement after impact, wind or corrosion, matching the existing profile as closely as it is available.
Metal roofing that pairs with this work is on commercial metal roofing, and completed elevations are in the project gallery.
How is the roof-to-wall junction detailed correctly?
Water is managed in layers, not stopped at a single line. A sound junction on a Toronto commercial building normally reads from the bottom up as: a cant strip at the base of the wall, the membrane carried up over it to an adequate height and fully adhered or mechanically secured at its termination, a termination bar or hooked edge holding the head, a counter flashing lapping over the top of that, and a cap flashing over the head of the parapet sloped back towards the roof with a drip on the outer face.
Three things then keep it alive: expansion provision in every long metal run, fastening into sound substrate rather than into deteriorated mortar, and sealant used only where it is protected and accessible for renewal. When we rebuild a detail we correct the height and the layering rather than reproducing what failed. If the wall itself is the source, meaning failed mortar joints or a missing through-wall flashing, we say so, because a new cap flashing will not fix a wall problem.
These junctions are checked on every visit under our roof maintenance program, and they are documented individually in a roof condition report.
When should flashing be rebuilt rather than repaired?
Repair a detail when the assembly is sound and the failure is a lap, a fastener, a length of sealant or a section of metal. Rebuild it when the base flashing height is inadequate, when the metal has no expansion provision and keeps opening, when the cant strip is gone, when the counter flashing has never been let into the wall properly, or when the same detail has been patched repeatedly.
The most economical time to correct every detail on a roof is during a flat roof replacement, when the perimeter is open, the new insulation height is being set anyway, and access equipment is already on site. Correcting details on their own is entirely possible and often worth doing, but it is a separate mobilisation.
Call 416-456-0777 or use the contact page for a free roof assessment. WSIB coverage and certificates of insurance are provided on request.
Frequently asked questions
Water is running down the inside of an exterior wall. Is that the roof?
Often it is the parapet rather than the roof field. Water gets behind loose or unsloped cap flashing, or through failed mortar joints in the parapet masonry, and runs down inside the wall. Because it never crosses the roof membrane, patching the roof changes nothing. We check the cap flashing, the counter flashing and the masonry together.
How high does base flashing need to go up the wall?
High enough that water backing up on the roof, and snow drifting against the wall, cannot get over it. That is why a re-roof that adds insulation must also raise the flashing, and why curbs that were adequate before an insulation upgrade often are not afterwards. We set the height for the specific roof rather than reproducing what was there.
Can you match our existing cladding profile and colour?
Usually. Profiles and finishes are formed and ordered to suit, and we identify the closest available match to the existing panel. Where a discontinued profile or a weathered colour cannot be matched exactly, we say so before ordering and discuss replacing a full elevation or a clearly defined section instead.
Do you do masonry repairs to parapets?
Our scope is the roofing and sheet metal work. Where the parapet masonry itself needs repointing, rebuilding or a through-wall flashing installed, we identify it in writing and coordinate with a masonry contractor so the roofing details are sequenced correctly around that work.
Is flashing repair worth doing on an old roof?
It depends on the field of the roof. If the membrane is sound and dry, correcting the details is one of the highest-value repairs available and can add real service life. If the assembly is already wet across the field, the money is better held for the replacement. A condition report answers the question before you spend.
Ready for your free roof assessment?
Tell us the address, the roof size and what you are seeing. We will book a time to get up there and put it in writing.
Call 416-456-0777 to book. Roof leaking right now? Our 24/7 emergency line is 416-450-1818.
Call 416-456-0777