Boroughs, island towns and suburbs we cover

The Ville de Montréal has 19 boroughs, each with its own permit counter. For same-size replacement, the city says plainly that the rules differ from one borough to the next (montreal.ca): most require a permit even for an identical window, a few generally don't, and several add conditions on materials, styles or door glass.

So check with your borough first. The pro we connect you with can help assemble the file, from the written soumission (the quote) to numbered photos; our guide to window permits by borough explains the rest. Westmount, the other island cities, Laval and the South Shore issue their own permits, and we haven't reviewed all of them, so call the city before you sign.

Most of the island's homes are flats in duplexes, triplexes and low walk-ups. Each dense plex district has a page, because each borough treats windows differently:

• Le Plateau-Mont-Royal and Mile End: repairing original windows generally needs no permit; replacing them means matching the originals.
• Rosemont–La Petite-Patrie: a published list of accepted replacement models.
• Villeray–Saint-Michel–Parc-Extension: classic duplexes with spiral stairs; wait for the permit before buying materials.
• Verdun: 1920s plexes, precise rules for door glass, and transoms that have to stay.
• Le Sud-Ouest: no PVC on the outside, and original stained glass goes back in.
• Notre-Dame-de-Grâce and Côte-des-Neiges: interwar houses, and no sliding windows in the significant sectors.

Downtown, Old Montreal, Hochelaga-Maisonneuve and Outremont are covered on the island-wide Montreal page.

Westmount is its own city, with its own review of exterior changes, but restoring original windows and replacing them identically are exempt from it. In Old Montreal, much of it a declared historic district, the borough favours keeping or restoring the original appearance. In places like these, repairing a sash or replacing a thermos (the sealed glass unit in the frame, as Montrealers call it in both languages) is often the simplest route through the rules.

• Saint-Laurent: the borough generally doesn't require a permit for an identical replacement, though sliding patio doors and bay windows need one everywhere in the city.
• Ahuntsic-Cartierville: a replacement has to match the original's form and typology, down to the opening type, the divisions and the colour.

Montréal-Nord, Saint-Léonard, Anjou and Rivière-des-Prairies–Pointe-aux-Trembles have no page of their own, and their rules range from a permit for every replacement to none for most identical ones; the Montreal page sets out the differences.

The West Island is mostly independent cities of detached 1960s and 70s houses, where English is the first language of many households; each city sets its own permit rules, so ask yours. Two nearby boroughs have no page: Lachine generally requires a permit only in its PIIA sectors, where designs go through architectural review, and LaSalle requires one even for a same-size replacement.

• Laval: a city of houses, most of them owner-occupied, with a large share built in the 1960s and 70s.
• Terrebonne and Repentigny on the North Shore: send your postal code, and we'll check whether a pro covers your address.
• Longueuil: many low-rise apartment buildings, a large share of them from the 1960s and 70s.
• Brossard: newer housing with many condominiums, where a window question often starts with the syndicate.

RénoPlex, the city's renovation subsidy, applies only on the Ville de Montréal's territory; Quebec's Rénoclimat applies province-wide. The subsidies guide explains both.