The permit answer depends on the deck and the municipality. Height is a useful starting point, but attachment to the house, size, use as an exit, and local zoning can also matter. A simple sketch with those details will get you a more useful answer than asking about a deck in general.
The 60 cm rule is a starting point
Toronto's official building-permit guidance says a deck more than 60 cm above ground requires a permit. It also says some uncovered platforms no more than 60 cm high may be exempt when they are not part of a required exit and comply with zoning.
Oakville's official deck guide is different in an important way: a deck greater than 10 m² and higher than 61 cm needs a permit, and any size deck attached to a house needs one. Every deck still has to comply with the property's zoning bylaw.
That is why a single internet rule cannot answer for every Ontario address. The province explains that permits are issued by the local authority and recommends contacting the municipal building department when the requirement is unclear. Start with the current Ontario building-permit guide, then use your city's project page for the actual application.
Check the property before drawing the deck
- Zoning: setbacks, lot coverage, height, easements, and where a deck is allowed.
- Finished grade: measure height at the relevant edges, not only at the back door.
- Attachment: decide whether the deck uses a ledger or is independently supported.
- Trees and regulated land: tree protection, heritage, or conservation approval may come first.
- Underground services: contact Ontario One Call before digging and arrange private locates where needed.
Do this before choosing the final deck size. Moving a line on a sketch is easy. Moving footings after construction is much more involved.
What the permit drawings need to explain
Toronto's current deck application guide and Oakville's guide ask for the same core story: where the deck sits, what supports it, and how people use it safely.
- A site plan with property lines, deck dimensions, setbacks, easements, and existing structures.
- A framing plan showing footing, post, beam, joist, cantilever, and ledger information.
- Elevations showing height above grade plus stair, guard, and handrail details.
- Sections showing footing and frost protection plus the connection to the house, if attached.
- Designer information and any engineering or outside approval the municipality requires.
The inspection-ready version
Build from the approved drawings and keep the permit set on site. Confirm the required inspection stages when the permit is issued. Do not cover footings, framing, ledger connections, or other work the inspector still needs to see. Confirm the inspection stage before laying the deck boards.
- Footing size, location, depth, and frost protection match the approved detail.
- Posts, beams, joists, hangers, fasteners, and spans match the drawings.
- The ledger and flashing detail protects the house and follows the approved connection.
- Stairs, landings, guards, handrails, and openings match the approved dimensions.
- Changes are approved before they are built, not explained during the final inspection.
Already looking at an unpermitted deck? Use the deck-without-a-permit guide. Planning a shed instead? The current Ontario 15 m² shed exemption has five conditions, not one. Planning a late-season start? Check whether a fall or winter deck build makes sense before setting the date. Then read the Ontario guard guide and bring the site details to our custom deck team. That order prevents a great deal of expensive improvisation.
