Finishing a basement in Toronto usually starts with permit and design costs of roughly $2,000 to $4,500. If the space is dry, finishing follows. If moisture is present, waterproofing runs $5,000 to $15,000 and must come first. Your total depends heavily on what the walls and floor are hiding.

What goes into the permit and drawings?

A finished basement is a building project, and the City of Toronto treats it that way. The permit itself is about $11 per square metre. You also need drawings stamped by a BCIN-qualified designer, which typically cost $1,500 to $4,000 depending on the layout and whether you are adding a bedroom, bathroom, or second unit.

Added together, the paperwork side of a basement finish lands at roughly $2,000 to $4,500 before a single wall goes up. Skipping the permit can stall a future home sale and create problems with insurance, so it is money worth spending up front.

Why does moisture have to be handled first?

A finished wall over a wet foundation traps water against the concrete. Mould grows behind the drywall where you cannot see it, and the drywall, insulation, and flooring you just paid for start to fail. Moisture gets handled before finishing, every time.

Basic waterproofing runs $5,000 to $15,000. A full interior drainage system, where a channel is cut around the inside perimeter to carry water to a sump pit, runs $8,000 to $15,000. Adding a battery backup to the sump pump costs another $300 to $800, and in a city where summer storms knock out power, that backup keeps the basement dry while the power is out.

Can the city help pay for it?

Yes, if your work guards against basement flooding. The City of Toronto Basement Flooding Protection Subsidy covers up to $6,650 per property toward eligible work like a sump pump, a backwater valve, and related plumbing. That figure is current as of May 2026, and the rules change, so confirm today’s terms and eligible items with the city before you book the work.

The subsidy will not pay for your new flooring or paint. It is aimed at the parts that keep water out, which happen to be the same parts you want done before any finishing begins.

What pushes the price up or down?

A dry, square basement with good ceiling height is the least expensive to finish. Costs climb when you add a bathroom, because that means new drain lines and often a pump. They climb again with a separate entrance, egress windows for a legal bedroom, or a kitchen for a basement apartment.

• Adds cost: a new bathroom, a kitchen, egress windows, a separate entrance, low ceilings that need floor work.
• Holds cost down: a dry foundation, an existing rough-in for plumbing, a simple open layout, and standard finishes.

How should you plan the budget?

Start with the foundation, not the finishes. Get a written, itemised quote that separates moisture work, permit and design, and the finishing itself. When those three numbers sit on one page, you can see where the money goes and decide what to do first.

What to do next

Have someone check the basement for moisture before you price out drywall and flooring. If the foundation needs work, that comes first, and the city subsidy may cover part of it. From there you can stage the project in a sensible order. See our basement finishing in Toronto service for how a full finish comes together, and call ArchCap at (289) 260-3971 to walk through your space and get a written quote before any work starts.