What the boroughs have in common
The City treats any roof with a slope under 2:12, or 16.7%, as flat or low-slope. That covers the great majority of plexes.
To reduce heat islands, most boroughs require a replaced flat roof to be light-coloured or reflective. The white roof rule comes in three forms.
- a white material, painted white, or covered with a reflective coating or white gravel
- a material whose solar reflectance index (SRI) meets the borough's threshold
- a green roof, also called a vegetated roof
Several boroughs accept a combination of these. The part of the roof taken up by mechanical equipment, such as a heat pump, or by a deck is generally exempt.
The 19 boroughs at a glance
| Borough | Permit to replace the roofing | Roofing required on a flat roof |
|---|---|---|
| Ahuntsic-Cartierville | Yes | Green roof, white material or reflective coating, white gravel, or SRI of at least 66 |
| Anjou | No, neither to repair nor to replace | White material, reflective coating, white gravel, SRI of at least 78, or green roof |
| Côte-des-Neiges–Notre-Dame-de-Grâce | No for the membrane, except for a heritage building whose flashing is modified. Yes for the roof structure | White material, reflective coating, white gravel, SRI of at least 56, or green roof |
| Lachine | Yes | Existing building: list of permitted materials, including torch-on or self-adhesive membranes. New construction: SRI of at least 78 or green roof |
| LaSalle | Yes | Roof under 300 m²: list of permitted materials, including elastomeric membrane and tar and gravel. Over 300 m²: white material or SRI of at least 56 |
| Le Plateau-Mont-Royal | No to replace the membrane, except for a heritage building. Yes if the insulation or structure is touched | New building, extension, change of volume or slope: green roof or SRI of at least 56 (white or light grey) |
| Le Sud-Ouest | Yes | Green roof, white material, white ballast, or SRI of at least 78. Built-up roofing allowed with a white gravel or marble ballast finish |
| L'Île-Bizard–Sainte-Geneviève | Yes | White material, reflective coating, white gravel, SRI of at least 78, or green roof. Asphalt, tar and gravel prohibited |
| Mercier–Hochelaga-Maisonneuve | Yes to fully renovate a roof. No for a partial replacement on a roof under 500 m² | White material, reflective coating, white gravel, SRI of at least 56, or green roof |
| Montréal-Nord | Yes | White material, reflective coating, white gravel, SRI of at least 78, or green roof |
| Outremont | Yes, to repair as well as to replace | White material or white ballast, green roof, or SRI of at least 78 on 75% of the roof, or at least 66 on the whole roof |
| Pierrefonds-Roxboro | No if the asphalt is replaced with an identical material. Yes if the material changes | Light-coloured material or reflective coating with an SRI of at least 66, or green roof |
| Rivière-des-Prairies–Pointe-aux-Trembles | No if the asphalt is redone with a similar material. Yes if the material changes | White or grey material, white or grey gravel, SRI of at least 78, or green roof |
| Rosemont–La Petite-Patrie | Yes | White material, reflective coating, white gravel, SRI of at least 78, or green roof. Tar and white gravel prohibited on a new building |
| Saint-Laurent | Yes | White gravel, SRI of at least 78, or green roof |
| Saint-Léonard | Yes | Single-family house: materials allowed by the building code. Other buildings: white material, white gravel, SRI of at least 82, or green roof |
| Verdun | Yes | Green roof, white material, white ballast, or SRI of at least 78 |
| Ville-Marie | Yes. No for a spot repair covering less than half of the surface | White material, reflective coating, white gravel, SRI of at least 78, or green roof |
| Villeray–Saint-Michel–Parc-Extension | Yes. Wait for the permit before buying materials | White material, reflective coating, white gravel, SRI of at least 66, or green roof |
The permit column refers to replacing flat roofing. In almost every borough, maintenance and minor repairs, such as adding tar, need no permit. As soon as the work touches the insulation or the roof structure, several boroughs require a permit even when a simple membrane replacement is exempt.
Boroughs that stand out
- Anjou requires no permit to repair or replace a flat roof, but still imposes the materials.
- Le Plateau-Mont-Royal lets you replace the membrane without a permit. Its reflectance requirement targets new buildings, additions and changes in slope or volume.
- Outremont requires a permit even for a repair.
- Saint-Léonard has the highest threshold, an SRI of 82, but it does not apply to single-family houses.
- Lachine and LaSalle work from a list of permitted materials rather than a single colour rule.
- L'Île-Bizard–Sainte-Geneviève bans asphalt, tar and gravel roofing.
Heritage buildings
A heritage building or heritage area has additional standards, fees and documents. In some boroughs, a permit becomes mandatory for work that would be exempt elsewhere. Your borough's permit counter confirms whether your building is affected.
Before you sign
This table is a summary. Bylaws change, and your building may have a feature the summary does not show. Always confirm with your borough's permit counter before ordering materials.
Ask us to write the exact product and its SRI into the quote. The manufacturer's technical data sheet is the document the borough wants to see.
Frequently asked questions
Does my borough require a white roof?
Most boroughs require white, reflective or green roofing when a flat roof is replaced. The SRI threshold and the exceptions vary. Find your borough in the table, then confirm with the permit counter.
Do you need a permit to redo a flat roof in Montreal?
Yes, in most boroughs, as soon as the roofing is replaced. Anjou does not require one, and a few boroughs exempt some replacements, such as replacing the membrane in Le Plateau-Mont-Royal.
How much does a permit to redo a flat roof cost in Montreal?
The permit costs $9.80 per $1,000 of work in most boroughs, and $11 in Montréal-Nord. The minimum is $167.40 for a strictly residential building and $491.70 for a commercial or mixed-use building. Anjou does not require a permit for a flat roof. These fees are non-refundable.
Is gravel still allowed?
Gravel is allowed or banned depending on the borough. Several accept white gravel as a reflective surface. L'Île-Bizard–Sainte-Geneviève bans asphalt, tar and gravel, and Rosemont–La Petite-Patrie bans white tar and gravel on new buildings.
Do these rules apply to a sloped roof?
No. These rules cover flat or low-slope roofs, under 2:12. Sloped roofs have their own rules, which the City presents separately.
Source: City of Montreal, « Rénover un toit plat ou à faible pente », consulted October 3, 2026.