Bathroom renovation in Montréal: trades, licences, permits

A bathroom brings several trades into one small room: plumbing, electrical work, ventilation, waterproofing, tiling. A mistake hidden behind the tiles is expensive to fix. Knowing who does what helps you choose the companies, read their quotes and avoid surprises.

1. A general contractor or specialists?

For a full renovation, a general renovation contractor coordinates the trades and is responsible for the whole job. For a simple replacement (a toilet, a sink, a faucet), a plumber is enough. Either way, check the licence of each company; our guide general or specialty contractor helps you decide.

2. Plumbing

Plumbing work must be done by a contractor holding subclass 15.5. Plumbers are most often members of the Corporation des maîtres mécaniciens en tuyauterie du Québec (CMMTQ). Moving the toilet or shower often changes the drain in the floor: ask whether it is feasible before you settle on the layout.

3. Electrical work

Adding an outlet, lighting, a fan or a heated floor is electrical work, reserved for an electrical contractor (subclass 16, licence issued by the Corporation des maîtres électriciens du Québec).

4. Ventilation

A properly sized fan that vents outside, not into the attic, protects the room and the house from moisture and mould. Ask where the duct will run and where the air will exit.

5. Waterproofing

Behind the shower tiles, a properly installed waterproofing membrane is essential. Ask in the quote which system is planned, on which surfaces and how high.

6. The order of the work

Demolition, plumbing and electrical, inspection if needed, waterproofing, finishes, then fixtures. Plan for a few days without a bathroom, longer if the house has only one.

Bathrooms in Montréal, Laval and Côte-Saint-Luc: permits and RénoPlex

The rules change from one city to the next, even on the island. In Montréal, replacing a sink or bathtub generally needs no permit, but you need one as soon as the work affects the walls or changes the size, division or use of rooms; some boroughs also require one for drywall on walls or ceilings (the City’s page on interior renovations). In Laval, renovating an existing bathroom needs no permit, but adding one does (page Rénovation résidentielle intérieure, in French). In Côte-Saint-Luc, a building permit is required to renovate a bathroom, and no work may start before it is issued (page Rénovations intérieures et extérieures, in French).

For a building with 1 to 5 dwellings in Montréal, the RénoPlex program (page updated June 19, 2026) lists plumbing and electrical work among its types of work, subject to property-value conditions; the page does not mention bathroom finishing. You must wait for your application to be accepted, 3 to 4 months according to the City, before starting. For a basement bathroom, also read our guide on basements and backwater valves. To find the trades, see plumbers in Laval, those in Le Sud-Ouest or electricians in Villeray–Saint-Michel–Parc-Extension.

Prices are easier to read with our guide on comparing quotes. No prices yet? Describe your current bathroom and the one you want.