Basement Finishing Cost in Montreal (2026)

Yes, a permit is required for any work that changes the structure, room dimensions, or use (e.g., adding a bedroom). In 2026, Montreal permit fees are $9.80 per $1,000 of estimated work, with a minimum residential fee of $167.40.

A professionally finished basement in the Montreal market typically yields an ROI of approximately 70%, significantly increasing the home's resale value by adding legal living space.

Adding a full 3-piece bathroom typically costs between $8,000 and $25,000 in 2026. The high cost is primarily due to the need for concrete trenching for new plumbing lines.

Under the Quebec building code, basement walls must meet a minimum R-value of R-24. In Montreal, this often requires closed-cell spray foam or high-performance rigid foam, costing between $5,000 and $12,000 for a standard 1,000 sq ft space.