Do you need a permit for a deck in Mississauga, Toronto or Oakville?

Usually yes if the deck is raised, and sometimes even if it isn't. In Mississauga and Toronto the deciding factor is height: a deck whose walking surface sits more than about 600 mm (2 ft) above the ground needs a building permit. Oakville adds a second trigger, because any deck attached to the house needs a permit there, however low it is. A low, freestanding deck generally needs no permit in any of the three cities, but it still has to meet zoning.

The table summarizes each city's published guidance. Municipal rules get updated, so confirm with your building department before you settle on a design.

Deck permit thresholds by city

A few details catch people out:

• Check the high side. On a sloping lot, a deck can be a step up at the door and well over 2 ft at the far edge. If any part of it is over the line, plan on a permit and confirm with the city.
• A roof changes things. Toronto's and Vaughan's exemptions are for uncovered decks, so adding a roof generally means a permit.
• Exits count. In Toronto, a low deck that forms part of a required exit from the house isn't covered by the exemption.
• Attachment in Mississauga. The city's guidance is written around height. If a low deck will be fastened to the house, ask the Building Division whether that affects your project.

A deck off a main-floor kitchen door or a walkout is often well above 2 ft, which is why so many raised decks go through the permit process.

What the permit application usually needs

Mississauga publishes a list of the drawings and documents it wants for a deck, porch or balcony, and Toronto's deck and porch guide asks for much the same. Expect to provide:

• A site plan or survey showing the house, the deck and the distances to your property lines.
• A framing plan with beam and joist sizes, spans and post locations.
• Footing details: size, spacing, depth and how the footings are protected from frost.
• Guard details wherever the deck needs a railing.
• Stair details, such as riser height and tread depth.
• The connection to the house, if the deck is attached.

The drawings also have to show who prepared them. Designers generally list their qualifications and Building Code Identification Number (BCIN), while a homeowner drawing plans for their own house is generally exempt from that requirement.

Footings: at least 1.2 m down in Mississauga

Footings decide whether a deck stays level. Mississauga's deck information sheet calls for footings that bear on undisturbed soil at least 1.2 m (4 ft) below finished grade. The point is to get below the soil that freezes. A footing sitting in frozen ground can be pushed up over the winter and drop back unevenly in spring, which racks the frame and strains the connection to the house.

Toronto's guide asks for footing depth and frost protection details on the drawings, and other municipalities set their own requirements. Your drawings should show the depth your city accepts.

Before any digging starts, request a free utility locate through Ontario One Call. Gas, hydro and cable lines can run through backyards.

Guards above 600 mm

The Ontario Building Code generally requires a guard (a railing) where a deck's walking surface is more than 600 mm (about 2 ft) above the ground next to it. In practice, the height that triggers a permit in Mississauga and Toronto usually means railings too, and the permit drawings show how they'll be built.

Railings are a real line in the budget. Ours run $45–$85 per linear ft in wood, $85–$130 per linear ft in aluminum and $150–$250 per linear ft in glass, plus HST.

Inspections

Once the permit is issued, the city inspects the work at set stages. Your permit lists the inspections that apply. For a deck they usually include:

1. Footings, after the holes are dug and before concrete goes in or the holes are backfilled.
2. Framing, before the decking covers the structure.
3. Final, once the decking, guards and stairs are complete.

Don't let anyone pour footings or lay boards before the matching inspection. Work that's covered too early may have to be opened up again so the inspector can see it. In Mississauga, inspections are booked with the city after the permit is issued.

Zoning applies with or without a permit

A deck that's exempt from a building permit still has to comply with your zoning by-law. Zoning typically controls how close a deck can be to your lot lines, how high it can sit in certain yards and how much of the lot can be covered. Corner lots, narrow lots and lots with easements are worth checking early, before the design is set.

How long a permit takes

Ontario's Building Code sets time limits for municipalities to decide on complete permit applications. Toronto, for example, reviews complete applications in its House Stream within 10 business days. Those limits only apply once the application is complete, so missing drawings or requests for revisions add time. Work that needs a permit shouldn't start until the permit is issued, so leave room in your schedule.

What drawings and a permit add to the cost

When a deck needs one, drawings and the building permit add $600–$2,500 to the quote, plus HST. Where yours lands depends on the size and complexity of the deck and on the municipality.

For context, the deck itself, including frame and footings, runs $30–$55 per sq ft in pressure-treated wood, $45–$75 per sq ft in cedar and $55–$90 per sq ft in composite, with railings and stairs extra. One raised pressure-treated deck we built with stairs and railings came to about $15,000. All prices are plus HST and are planning figures, not quotes. Your price comes from a site visit.

Whoever handles the paperwork, put it in the contract. Be wary of anyone who suggests skipping a permit your deck needs, or who asks you to apply in your own name so they don't carry the responsibility. Our guide to hiring a contractor in Ontario covers what else to check.

Planning a deck?

We build decks in Mississauga, Toronto, Oakville and across the GTA. See our deck building service for what's included, compare materials in pressure-treated vs. cedar, or book a free on-site estimate and we'll look at height, attachment and footings for your yard.