The deck looks simple on your sketch. The permit answer can still depend on where you live, how high it sits, and how it connects to the house. Before ordering lumber, put those details on one page. You will get a much better answer from the municipality than “just a small deck, probably.”
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.
Which deck are you planning?
| Your plan | What to check first |
|---|---|
| Low, uncovered platform in Toronto | Check finished height, required-exit status and zoning against Toronto's exemption. Low does not settle all three. |
| Deck attached to an Oakville house | Oakville requires a permit at any size. Making it smaller does not remove the attachment trigger. |
| Detached Oakville deck over 10 m² and over 61 cm high | Both dimensions meet the town's stated permit trigger. Check zoning before choosing the footprint. |
| Deck on a sloping yard | Record height at the outside edges as well as the house. Ask how the municipality wants adjacent grade shown. |
| Existing deck with new boards | Describe whether you are replacing only the surface or also changing framing, stairs, guards, height or footprint. Ask about that actual scope. |
These examples apply the Toronto permit list and Oakville deck guide, checked October 10, 2026. They are not a province-wide exemption table. A freestanding deck removes the house connection, but it does not automatically remove permit or zoning requirements. Compare freestanding and attached decks before deciding how yours will be supported.
Replacing boards, rebuilding, or adding a roof?
Put the old and proposed work side by side. Replacing deck boards is a different scope from replacing beams and footings, moving stairs or enlarging the platform. Toronto lists structural alterations and enclosing an existing deck among permit-required work. Do not describe a rebuild as maintenance just because the new deck occupies the same spot. For a surface-only plan, first check whether the existing frame can stay.
Adding a roof or pergola? Include the proposed cover in your permit inquiry and describe whether it has open slats, adjustable louvres or a solid roof. Our covered-deck and pergola guide explains the details to show with the deck.
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. For property within a TRCA-regulated area, TRCA's deck guidance covers permits for new and replacement decks. Check with the conservation authority responsible for your property. If a mature tree is close to the proposed footings, plan deck layout around protected roots before choosing support locations.
- Underground services: contact Ontario One Call before digging and arrange private locates where needed.
At one sloping backyard, the owner had measured only at the patio door and described the deck as low. A walk around the proposed outer edge told a different story. We added the grade measurements to the sketch before the permit inquiry. Take those measurements early, along with the stair footprint; a deck that fits on the plan can still land its bottom step in the route you need for the lawn mower.
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. We mark the inspection stops on the work schedule before booking the board delivery. That leaves an obvious pause instead of a crew staring at stacked decking, wondering whether to carry on. Confirm the required stages when the permit is issued, and keep footings, framing, ledger connections and other required details visible until inspected.
- 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. For the next design decision, read the Ontario guard guide: the height that starts a permit conversation also affects how you plan the deck edge.