Basement finishing in Montréal runs from about $15,000 for an open, drywalled rec room to $40,000-plus for a full suite with a bedroom, bathroom, and egress window. Final cost depends on size, plumbing, waterproofing, and permits. DemoPrep handles the demo-to-finish work directly — RBQ-licensed, one crew.
What Basement Finishing Costs in Montréal
| Scope | Starting Price |
|---|---|
| Open finish — framing, insulation, drywall, flooring, lighting | From $15,000 |
| Full finish — bedroom, full bathroom, egress window, wet bar/kitchenette | From $40,000 |
These are starting ranges, not quotes. What moves the number: total square footage, whether you’re adding a bathroom (plumbing + drainage), egress windows for a legal bedroom, waterproofing or moisture issues to fix first, ceiling height, and permits. We confirm the real figure after a site visit.
Finishing vs. Just Renovating a Basement
Finishing means turning an unfinished or builder-grade basement into proper living space — framing, insulation, drywall, flooring, and often a bathroom or bedroom. If you’re after layout inspiration first, see our basement renovation ideas for Montréal homes; this page is about what the work costs and how it’s done. Either way, DemoPrep runs it as part of our renovation services.
Why Montréal Basements Need the Right Crew
- Moisture comes first: older Montréal foundations can take on water — finishing over a damp basement traps the problem. We address waterproofing and drainage before framing.
- Egress and code: a basement bedroom legally needs an egress window. We build to the Québec construction code so the space is safe and adds resale value, not a liability.
- Old materials: homes built before 1990 can hide asbestos in old floor tile or insulation. We test before any demo and contain it if found.
Our Basement Finishing Process
Step 1 — Site visit, moisture check, and scope
We assess the foundation, check for moisture, confirm what you want (rec room, bedroom, bathroom), flag any asbestos in old materials, and give you a written scope and price.
Step 2 — Demo, waterproofing, and prep
Old finishes come out, any moisture issue is fixed, and the slab and walls are prepped. Where asbestos is confirmed, crews work under containment with MSA Advantage 3200 full-face respirators with P100 Flexi-Filters and HEPA filtration at 99.97%.
Step 3 — Build and finish
Framing, insulation, electrical and plumbing rough-in, drywall, flooring, and finishes — through to a clean, finished space.
Permits and Local Context
- Adding a bedroom or bathroom downstairs almost always needs a permit, and egress requirements are enforced — rules differ by borough and West Island city.
- Older central and east-end homes (Plateau, Rosemont, NDG) often need foundation and moisture work first; newer West Island and South Shore builds usually finish faster.
We confirm and pull what’s required — see the City of Montréal’s interior renovation permit process.
One Partner from Demo to Finish
DemoPrep is a full-service demolition and renovation company — RBQ #5826-5448-01. We don’t hand your basement off between a demo crew, a framer, and a finisher — one accountable team takes it from the first wall out to the finished room, or we partner directly with your general contractor on larger projects.
Get a Free Basement Finishing Quote
Thinking about finishing your basement in Greater Montréal?
Contact DemoPrep for a free basement finishing assessment
Frequently Asked Questions
How much does basement finishing cost in Montréal?
An open, drywalled finish typically starts around $15,000; a full finish with a bedroom, bathroom, and egress window starts around $40,000. The real figure depends on size, plumbing, waterproofing, and permits — we quote after a site visit.
Do I need a permit to finish my basement?
Usually yes, especially when adding a bedroom or bathroom. Egress windows for a legal bedroom are enforced, and requirements differ by borough and city. We confirm and handle the permit as part of the job.
My basement gets a bit damp — can you still finish it?
Not until the moisture is fixed. Finishing over a damp basement traps the problem and ruins the work. We address waterproofing and drainage first, then build.
Can you add a legal rental suite downstairs?
Often yes, if the ceiling height, egress, and code requirements can be met. We assess feasibility during the site visit and build to code so it’s a safe, value-adding suite.