Repairing a roof in Saint-Laurent
A repair often starts with a sign seen from inside, like a ring on the ceiling, blistering paint or a damp smell. Note the spot, the date and the weather of the previous days. Take photos inside, and outside from the ground or a window.
Do not go up on the roof, even a flat one, and do not get the ladder out. We go up there. Your job is to protect the inside, document and call.
This site is about roofing in Montreal. It explains the rules and lets you ask for a quote for a building in Saint-Laurent.
Buildings in the borough
Saint-Laurent is a former city, and its buildings are varied. You find houses with shingled sloped roofs, plexes and apartment buildings with flat roofs, condominiums, and commercial and industrial buildings with large flat roofs.
The City does not treat every roof the same way. It considers a roof flat or low-slope when its slope is under 2:12. From 2:12 up, it is a sloped roof. In Saint-Laurent, each has its own procedure and its own rules.
What needs a permit and what does not
For a flat or low-slope roof, the City's page for Saint-Laurent says:
- maintaining or repairing the roof needs no permit, adding tar for example
- touching the insulation or structure needs a permit
- installing or replacing the roofing needs a permit
For a sloped roof, the rule is more flexible:
- repairing or replacing the roofing needs no permit
- the roof must keep the same shape and the same load as the existing roof
- changing the structure needs a permit
- replacing the roofing with a material other than the one already in place needs a permit
A repair can change category along the way. We open a flat roof to seal a leak, find soaked insulation and suggest replacing it. At that point the work touches the insulation and a permit becomes necessary. Ask us to warn you before going beyond what was planned.
The City's page draws no precise line between a repair and a partial replacement of flat roofing. If your work covers a large part of the roof, ask the permit counter before starting.
The Saint-Laurent permit counter
The service point the City lists is the Saint-Laurent permit counter, 777, boulevard Marcel-Laurin. For a white roof or a green roof, the City recommends applying there in person. It adds that you can also apply online.
When a permit is required, the City charges a review fee of $9.80 per $1,000 of work. The minimum is $167.40 for a strictly residential building and $491.70 for a commercial, industrial, institutional or mixed-use building. Fees are non-refundable.
The pages consulted give neither the counter's opening hours nor processing times. Check with the borough before you go.
Four topics covered for Saint-Laurent
Flat roofs. The borough sets the materials allowed when flat roofing is redone: white gravel, a material with a solar reflectance index of at least 78, or a green roof. That page covers the three options and the parts of the roof that are exempt.
Shingle roofs. The sloped roof is the simplest case in Saint-Laurent, provided you keep the same material, shape and load. That page explains what these three conditions mean when you pick new roofing.
Commercial roofing. Commercial, industrial, institutional and mixed-use buildings pay a higher minimum permit fee. That page is for the manager who has to plan the file, the rooftop equipment and the schedule.
Full roof replacement. Redoing a whole roof means putting the steps in the right order: quote, documents, application, permit, then work. That page follows the process from start to finish.
Frequently asked questions
Do you need a permit to repair a roof leak in Saint-Laurent?
No, as long as it is maintenance or repair. The City's page for Saint-Laurent gives replacing a few shingles and adding tar as examples. If the repair touches the insulation or structure of a flat roof, a permit becomes necessary.
My building has heritage value. What changes?
The City states that extra fees may apply if the building or its area has heritage value or is subject to special architectural standards. The pages consulted do not say which fees. The permit counter can confirm whether your address is affected.
Will my insurer pay for the roof repair?
Your insurer's answer depends on your policy and the cause of the damage. Call your insurer before having the repair done, and ask which documents they want to see. Dated photos and a written quote help in every case.
Who applies for the permit, the owner or the roofer?
The City allows an agent to apply with a power of attorney authorizing them to act on the owner's behalf. State in the contract who files the application and who pays the fees.
Official sources, consulted October 3, 2026: