Basement Finishing in Toronto & the GTA

Does finishing a basement need a building permit?

In Toronto, it depends on what the work includes. Toronto Building's list says finishing a basement needs a permit when it includes structural or material alterations, new or changed plumbing or heating, new foundations or underpinning, a basement entrance, or a second unit.

Finishing an open basement with insulation, drywall and flooring, without new rooms or plumbing, needs none. A new bathroom does, because it adds plumbing, and so do new walls that change the rooms. When do I need a building permit? has the city's full list.

Your quote names the permits your job needs and who applies for each. Work a permit covers starts once it is issued, and new wiring gets its own notification of work from the electrical contractor.

Why check for moisture before anything is framed?

Because a finished wall hides water until the damage is done. Drywall, wood framing and carpet all grow mould once they stay damp, and you won't see it until it shows through. Health Canada's advice on mould starts with finding and fixing the moisture.

So the foundation walls and floor are checked before framing: for damp patches, staining, cracks that let water in, and the white crust called efflorescence that water leaves on masonry. A basement that takes on water needs that fixed first, by waterproofing or drainage work.

Toronto doesn't require a permit for waterproofing repairs. Installing a backwater valve or underpinning the foundation does need one.

Does a basement bedroom need a bigger window?

Often, yes. Under the Ontario Building Code, every floor with a bedroom needs at least one window or outside door that opens from the inside without keys or tools. The window needs a clear opening of at least 0.35 square metres, with no side under 380 millimetres.

Many older basement windows are smaller than that. Enlarging a window opening needs a building permit in Toronto, so a bedroom is planned around its window from the start. Ontario's Fire Code also requires a working smoke alarm on every storey, so a finished basement gets its own.

Should you test for radon before finishing a basement?

It's worth doing. Health Canada recommends testing every home for radon with a long-term test of at least 3 months, ideally through the heating season, in the lowest level you use regularly. Once a basement is finished, that is usually the basement.

Testing first keeps the fix simple. If the level comes back high, the usual remedy is a pipe and fan that draw air from under the floor slab. That pipe is easier to route before the walls and ceiling are closed in. Testing your home for radon explains the test and Canada's guideline.

What does finishing include, and how does it end?

Framing, insulation and drywall come first, then flooring, trim, doors and paint. A bathroom or a wet bar brings in a plumber, and new lighting and outlets an electrical contractor, each holding their own Ontario licence.

The last step is the one we know best. New drywall takes a primer made for it before any colour, because fresh joint compound and drywall paper soak up the first coat unevenly. Do you need primer? explains why, and our interior painting page covers the paint itself.