In Montreal, a standard-quality basement renovation runs $27,435 to $63,705, prices below the Canadian average (index 93). A budget version starts around $19,205 and premium work reaches $101,928.
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| Line item | Range | Share |
|---|---|---|
| Framing, Drywall, Insulation & Ceiling | $5,208 – $14,322 | 31 % |
| Flooring | $1,953 – $4,557 | 10 % |
| Bathroom | $5,208 – $11,718 | 27 % |
| Kitchen | $5,208 – $10,416 | 24 % |
| Electrical | $1,628 – $3,581 | 8 % |
Included
Not included
| Line item | Range | Share |
|---|---|---|
| Framing, Drywall, Insulation & Ceiling | $7,440 – $20,460 | 31 % |
| Flooring | $2,790 – $6,510 | 10 % |
| Bathroom | $7,440 – $16,740 | 27 % |
| Kitchen | $7,440 – $14,880 | 24 % |
| Electrical | $2,325 – $5,115 | 8 % |
Included
Not included
| Line item | Range | Share |
|---|---|---|
| Framing, Drywall, Insulation & Ceiling | $11,904 – $32,736 | 31 % |
| Flooring | $4,464 – $10,416 | 10 % |
| Bathroom | $11,904 – $26,784 | 27 % |
| Kitchen | $11,904 – $23,808 | 24 % |
| Electrical | $3,720 – $8,184 | 8 % |
Included
Not included
In Montreal, Quebec, a standard-quality basement renovation typically costs between $27,435 and $63,705 in 2026 — prices are below the Canadian average, with a local cost index of 93%. Expect around 6 to 12 weeks of work and a 50–75% return on investment at resale. Exterior foundation insulation plus an interior sub-slab vapour break is the gold standard here — ice-damming at the rim joist is the most common retrofit failure.
Same job in Laval: $26,255 – $60,965 at standard quality, about 4 % cheaper than Montreal on our cost index.
Montréal basements come in two kinds: the plex basement dug deep for a boiler room, which finishes easily, and the low basement of a cottage or a duplex on the West Island and in the older boroughs, where gaining height means excavation or underpinning, sometimes in rock, a structural job quoted apart from the finish. Flood-prone sectors along the Rivière des Prairies make the backwater valve and sump the first line of the budget, and RénoPlex pays part of both. Permits go through the borough at a rate set citywide; whether the borough requires one for your finish is the borough’s call.
Authority: Ville de Montréal, your borough’s permit counter
Guide: Renovating in Québec: licences, taxes, permits and programs (2026)
Before any basement finishing work, address moisture issues first — this is non-negotiable in Canada. Have a professional assess the foundation for cracks, water infiltration, and radon levels. Basement ceiling height determines your options: 7 feet minimum is required by building code for habitable space. Plan electrical and plumbing rough-ins for a future bathroom even if you're not building one now ($500–$1,000 upfront saves $3,000–$5,000 later).
Waterproofing and moisture mitigation ($2,000–$8,000) is the largest variable cost. Egress windows are required by code for bedrooms and typically cost $2,500–$5,000 each installed. Underpinning (lowering the floor) costs $30,000–$70,000 but creates significant value in homes with low basements.
Pro tip
Install a sump pump with battery backup before finishing your basement — even if you've never had water issues. One flood can destroy $20,000+ of finished basement, and climate change is increasing urban flooding across Canada.
Montréal's renovation market is a plex market: duplexes and triplexes with shared walls, common elements and a syndicate when the building is a divided co-ownership. A large, bilingual pool of RBQ-licensed contractors serves it, and the cost index sits between Québec City and Toronto.
Cold winters, hot humid summers and repeated freeze-thaw: insulation, air sealing and materials rated for it matter more than in milder cities. Snow load is a design factor for roofs, and ice dams are common on older homes without proper attic ventilation.
Our 2026 estimate for a standard finish is $27,435 to $63,705; a budget finish starts near $19,205 and a premium one with a full bathroom reaches $101,928. Excavation or underpinning to gain ceiling height is not in these figures.
It is a separate structural job, quoted after an engineer looks at the foundation, and it can cost more than the finishing itself. Get it quoted on its own, with the engineer’s report, before deciding whether the extra height is worth it.
Yes, through RénoPlex: $90 for a normally-closed backwater valve, $600 per valve when it goes under an existing slab, and $1,600 per building for a new retention basin with pump, for houses and buildings of up to five units.
$9.80 per $1,000 of work, with a minimum of $167.40 for a strictly residential building; the borough issues it. Whether your project needs one depends on the borough’s rules, so ask before demolition.
Close to it. Our Laval page has its own figures; for Longueuil and the South Shore, use the Montréal range and expect similar labour rates with the same RBQ and tax rules.
Complete guide
Read our complete national guide to basement costs