A deck permit feels intimidating, but it is mostly paperwork — and in Ontario you are allowed to apply for and design your own deck permit as the homeowner. Below we answer the 14 questions homeowners ask most, grouped so you can jump to what you need. This page is part of our complete guide to building a deck in Ontario.

Do you need a deck permit in Ontario?

1. Do I even need a permit for my deck?

Usually yes. In most Ontario municipalities you need a building permit if the deck is attached to the house, or if any walking surface sits more than 600 mm (about 24 inches) above the ground. Low, freestanding decks under that height are often exempt — but always confirm with your local building department.

2. How big can a deck be without a permit?

For a freestanding deck, many towns exempt it only when it is both under about 10 m² (108 sq ft) and under 600 mm above grade. Go over either threshold, attach it to the house, or have it serve a principal entrance, and a permit is required regardless of size.

3. Does a freestanding (floating) deck need a permit, or only attached ones?

Attached decks almost always need a permit once over 600 mm high. A truly freestanding deck is judged on height and area: low and small is often exempt, but anything over ~10 m² or 600 mm, or that provides principal access, still needs one. Zoning setbacks apply either way.

4. A ground-level deck attached to the house — permit or not?

If it is genuinely at grade (under 600 mm) it may be exempt even when attached, in some municipalities. But the attachment itself triggers a permit in others, such as Toronto. Because towns differ on this exact case, confirm with your building department before assuming you are exempt.

14. Even with no permit, does it still have to meet code and setbacks?

Yes. Permit-exempt is never code-exempt. An exempt deck still must meet the Ontario Building Code for structure and guards, respect your zoning setbacks, and keep clear of septic systems. Exemption only removes the paperwork, not the standards — see our deck setbacks and zoning guide.

What happens if you skip the permit?

5. Can I get away without a permit — and what is the real risk?

You can, and many do. But if a neighbour reports it or it surfaces during a home sale, you can be ordered to obtain an as-built permit, expose finished work for inspection, and pay penalties. At a deck’s low permit cost, doing it right is the cheaper, lower-stress path.

6. What is the fine if I am caught?

Under Ontario’s Building Code Act, building without a required permit can bring fines up to $50,000 for a first offence (far higher for corporations and repeat offences). In practice you usually first get an order to apply and may pay a doubled permit fee — but the legal exposure is real.

7. Will an unpermitted deck hurt me when I sell?

It can. Buyers’ lawyers and home inspectors flag work done without permits, which can delay closing, reduce your price, or force you to legalize the deck under a deadline. A clean permit history is a selling feature, not a formality — and it removes a common closing headache.

8. Will it void my home insurance?

Possibly. Insurers can deny a claim tied to unpermitted structural work — for example, if someone is injured when an unpermitted deck fails. Read your policy, but treat the permit as part of protecting your coverage, not just satisfying the city.

13. Will the city actually find out, or can a neighbour report me?

Yes — anyone can report unpermitted work, and municipalities also catch it through aerial imagery, future permit applications, and property sales. You cannot rely on staying unnoticed, especially since the deck stays on your property in plain view for years.

Rebuilds, stairs, and after-the-fact permits

9. Can I get a permit after the deck is already built?

Yes — it is called an as-built or retroactive permit. You apply as normal, and the inspector verifies what exists, sometimes asking you to expose footings or framing. It is more hassle than permitting first, but it clears the record and is far better than an open violation.

11. Do I need a permit to rebuild or replace an existing deck, or just re-board it?

Simply replacing surface boards on a sound structure usually does not need a permit. But rebuilding or altering structural parts — joists, beams, posts, footings, stairs, or guards — does. Several towns, such as Oro-Medonte, require a permit for these structural repairs explicitly.

12. Does adding stairs or a landing trigger a permit?

Adding or rebuilding stairs and landings is structural work and generally requires a permit, especially when the deck itself is permittable. New stairs must also meet code for rise, run, and handrails — see our deck stairs and handrails guide and the stair stringer calculator.

Who applies — you or your contractor?

10. Can I apply for the permit myself even if a contractor builds it?

Yes. As the owner you can be the applicant and the designer for your own home’s deck — no BCIN designer and no engineer needed for a standard rectangular deck built to the span tables. Just agree in writing with your contractor who pulls it, since that name carries responsibility. Compare paths in our hiring a deck builder guide.

If your lot is near water, a slope, or a wetland, you may also need conservation authority approval before the permit can be issued — common across Simcoe County and Georgian Bay.

What a deck permit costs in Ontario (2026)

Fees are set by each municipality and reset every January, so confirm the current figure. These are representative 2026 amounts:

Add the cost of materials and, if you go outside the prescriptive span tables, an engineer’s stamp. See the full picture in our cost to build a deck in Ontario guide, or estimate yours with the deck building calculator. The provincial rules behind all of this are explained in our Ontario Building Code guide, and your footings must reach below frost depth — see deck footings.

Frequently asked questions