Flat roofs in TPO or SBS elastomeric membrane, drains, parapets and roofs of heritage buildings: the replacement is planned around the building, its occupants and your borough’s rules.
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Commercial roofing
Replacement of flat roofs in heat-welded TPO membrane or 2-ply SBS elastomeric, over tapered rigid insulation, for commercial buildings, retail stores and heritage buildings.
On a flat roof, watertightness depends on a whole assembly: the membrane, the insulation that creates the slope, the flashing at the joints and the drains. When one of these fails, water eventually reaches the roof structure and the top-floor ceilings.
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We do complete roof replacements, from tearing off the old system, such as tar and gravel, to the counter-flashing. We also handle what surrounds the roof: mechanical equipment, shoring, asbestos testing and affected ceilings.
A single-ply thermoplastic polyolefin membrane, welded with hot air, so there is no open flame on the roof. White, reflective and light, its welds can be checked by eye and repaired with hot air.
SBS-modified bitumen installed in two plies: a base ply and a granulated cap ply. This double layer provides redundancy that is valued in our climate of freezing, thawing and snow. Torch-free installation on an older roof structure.
Tear-off of the old system down to the roof deck, replacement of damaged decking upon written approval, then polyisocyanurate insulation of varying thickness that rebuilds the slopes toward the drains, and a cover board under the membrane.
Leaks often start at the joints: parapets, masonry, unit curbs, skylights. New metal flashing and counter-flashing, caulking and waterproofing details.
A blocked drain turns the roof into a pond. Restoration of the drains and stormwater drainage, new strainers and flow tests.
Re-anchoring rooftop units (heating, ventilation, air conditioning) with seismic restraints that comply with Part 4 of the National Building Code, replacement of corroded piping and verification of drainage slopes.
Torch-free methods, shoring of the roof structure according to a plan signed and sealed by an OIQ member engineer, asbestos and lead testing before stripping, crane lifting and dust partitions if the building is occupied.
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A flat roof deteriorates in stages. Here is how we read what you see.
Puddles that remain after rain or clogged drains: the slopes or the drainage are no longer doing their job. Maintenance may be enough if the membrane is sound.
Blisters, open seams, gravel piling up, flashing pulling away from the parapets: the roof is nearing replacement. A visit lets us compare repair and replacement.
Stains on the ceiling, sagging ceilings or mold: water has reached the structure. We work on the roof and can restore the ceilings in the same project.
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From the roof visit to the written warranty.
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The roof and everything around it, under one responsibility.
Depending on the municipality and the building, a heritage review or plans signed by a professional may be required. Permits are excluded from our quotes and coordinated with you.
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Roofing terms, so you can read a quote without getting lost.
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We replace commercial, multi-unit and heritage roofs in Montreal, on the North Shore, including Laval, and on the South Shore.
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It all depends on the building. TPO is single-ply, light, white and installed without a flame; 2-ply SBS elastomeric relies on the redundancy of its two layers. The roof structure, fire safety and how the roof is used guide the choice.
Yes. We close off the work areas, protect the entrances and warn occupants about the noisy phases with a communication plan.
It depends on the municipality and the building. Depending on the location, a heritage review or plans signed by a professional may be required. Permits are excluded from our quotes and coordinated with you.
In Montreal, a permit is required to install or replace the covering of a flat or low-slope roof (slope under 2:12). Depending on the borough, the new covering must be white, reflective or green, with a minimum solar reflectance index (SRI) that ranges from 56 to 82 depending on the by-law. The part of the roof occupied by mechanical equipment or a terrace is not covered. We check your borough's requirement before choosing the membrane. Source: City of Montreal.
Yes. Before work that can release asbestos dust, the CNESST requires checking for the presence and type of asbestos. Materials likely to contain it, such as some shingles and insulation, are presumed to contain it until proven otherwise, by a lab analysis or a technical data sheet. Buildings constructed before February 15, 1990 must also be inspected to locate sprayed-on materials. Source: CNESST.
Our prices are based on the current wage rates of the Commission de la construction du Québec (CCQ), set by the collective agreements for the sector concerned (residential, institutional and commercial, industrial), plus the materials and equipment specific to each job. Every quote is free, detailed and prepared after a site visit.
Both are suitable for flat roofs. Elastomeric, in two layers of modified bitumen, is very common in Quebec and stands up well to foot traffic. TPO, a white single-ply membrane, reflects heat and is installed without a flame. The choice depends on the building, the insulation, the rooftop equipment and the budget: the quote explains which one we recommend and why.
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Our guides on roofing.
Comparing the two membranes based on the building and its use.
Read the guide →Sheet 02 · GuideTorch-free installation, shoring and asbestos management.
Read the guide →Sheet 03 · GuideProtecting occupants during the replacement.
Read the guide →Next step
Describe what you see in the form below and attach photos of the roof or the ceilings. We will schedule a visit, then give you a detailed written quote.
Describe my projectPage updated October 17, 2026.
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