Why a replacement needs a permit
The City classes replacing the covering as a major repair. A permit is also required when the roof structure is changed or the insulation is touched.
The process, in order
- Establish the type of roof. Below a slope of 2:12, the flat or low-slope roof procedure applies. From 2:12 up, the roof falls under the sloped roof procedure. We measure it during our visit.
- Check the building's status. Ask the permit counter whether the building or its area has heritage value or is subject to special architectural standards.
- Choose a permitted material. On an existing flat roof, the City publishes a list that includes heat-welded or self-adhesive membranes, copper and zinc. On new construction, you need a solar reflectance index of at least 78, a green roof or a combination of the two. For a sloped roof, the procedure gives no list.
- Get a detailed quote. It must give the cost of the work, taxes included, and name the materials. Ask for the data sheet of each product.
- Gather the documents and file the application. The list is below. Filing is done online or at the counter.
- Schedule the job once the permit is in hand. The City page does not say how long the review takes in Lachine.
What the permit costs
Review fees are calculated on the estimated cost of the work, at $9.80 per $1,000. The estimate must include all related costs, taxes included, such as plans, labour and equipment.
A minimum applies whatever the amount, $167.40 for a strictly residential building and $491.70 for a commercial, industrial, institutional or mixed-use building.
The fees are non-refundable. Extra fees may be added for a heritage building or area, with no published amount.
Documents to gather
For both roof types, the City asks for:
- the quote or a cost estimate grid for the work, taxes included
- the certificate of location
- the technical data sheet for the planned materials, showing the solar reflectance index
- any other document useful to the review
For a flat roof, the City adds a structural plan approved by a professional, when the law requires it.
Depending on your situation, add:
- in a condo, a letter of authorization from each co-owner or a resolution of the syndicate
- if someone applies on your behalf, a power of attorney authorizing that person to act in your name
Where to file the application
Online. The City service lets you make all renovation permit applications at once. You need an account on montreal.ca. Payment is by credit card.
In person. The Lachine permit counter is at 1800, boulevard Saint-Joseph. The procedure does not say which payment methods are accepted there.
Frequently asked questions
How long does it take to get the permit?
The City page gives no processing time for Lachine. Check with the permit counter before setting the work date with us.
Can the roofer apply for the permit for me?
The City provides for an agent, who supplies a power of attorney authorizing them to act on the owner's behalf. Have the contract state who files the application and who pays the fees.
What happens if the roof is redone without a permit?
The procedures consulted do not say what happens when a roof is redone without a permit. The Lachine permit counter can tell you about the consequences and how to regularize the situation.
Official sources, consulted October 3, 2026: