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Do I Need a Building Permit in Ontario?
Do I need a permit?
Project by project
Ontario – plain answers
Do I Need a Building Permit in Ontario? The Honest, Project-by-Project Answer
Short version: you need a permit when the work is structural, changes the use of a space, adds or moves plumbing, gas, or wiring, or touches a life-safety item like egress, fire separation, or a deck up in the air. Cosmetic like-for-like work usually does not. Below is the straight answer for the projects people actually ask about, the thresholds that matter, and where folks get into trouble. We have pulled permits in these townships for 45 years, so this is what actually happens, not a brochure.
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Everything a builder does to coordinate a permit – the part that costs about $10,000 – in one plain-English playbook. Good anywhere in Ontario.
- The exact step-by-step to file your own permit – who to hire, in what order
- The complete-application checklist, so it does not get bounced
- Real fees, development charges, and design costs
- How to never fail an inspection – and the mistakes that cost the most
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Grab the DIY Bible, or hand it to us. We draw the permit-ready set and can review your package before you file – anywhere in Ontario.
- The full set your city wants: site plan, floor plans, elevations, sections, details
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The simple rule (memorize this and you will be right most of the time)
You PROBABLY need a permit when you…
change the structure (walls, beams, foundations), add or move plumbing, gas, or wiring, change the use of a space (garage to bedroom), build something with a foundation (garage, addition, big shed), or touch a life-safety item (egress windows, fire separation, decks more than 60 cm off the ground).
You PROBABLY do not when you…
do cosmetic, like-for-like work: paint, flooring, cabinets and counters in the same spot, swapping a fixture where it already sits, a small ground-level deck, or a shed under 15 m2 (about 160 sq ft) with no plumbing. Zoning setbacks still apply even when no permit does.
The one that costs people money: “probably not” is not “definitely not.” A wall you think is non-structural, a basement bedroom without a real egress window, a shed with a tap in it – these flip a no-permit job into a permit job. When the answer matters and you are not sure, get it confirmed before you build, not after an inspector finds it.
Got a Code question this page did not cover?
The permit follows the Ontario Building Code, and the Code is big. Ask our OBC Code Navigator your exact question – the first two questions are free. It is the fastest way to get a real answer for your project (and you can grab the OBC PDF there too).
Do I need a permit for…? (by project)
Deck
Usually yes if it's more than 60 cm (24 in) off the ground, attached to the house, covered, or part of an exit. A low ground-level deck is often fine without one.
Even when the deck itself is exempt, the zoning setback still applies – you cannot drop it on the lot line. The minute you add a roof, it is a structure and needs a permit. (See our deck pages and the deck calculator before you build.)
Shed / accessory building
No permit if it's 15 m2 (about 160 sq ft) or smaller AND has no plumbing. Bigger than that, or any plumbing, and you need one.
Zoning still controls where it sits and how much of the lot you cover – the permit exemption is not a zoning exemption. Put a tap or toilet in it and the exemption is gone.
Fence
No building permit for a normal fence, but it has to follow the municipal fence by-law for height and location. A pool fence is a different animal.
Pool enclosures have their own mandatory rules and inspection. Do not treat a pool fence like a garden fence.
Finishing a basement
Almost always yes. Framing, wiring, often plumbing, egress windows, fire separation, ceiling height – all of it is permit territory.
This is where DIY homeowners get burned at resale and on insurance. An unpermitted finished basement is the classic thing that blows up a house sale.
Basement apartment / second unit
Yes. A legal second unit needs a permit and has to meet fire separation, egress, ceiling height, smoke/CO, and ventilation rules.
Bill 23 made second units broadly allowed by zoning, so you usually skip the rezoning – but the building permit and the Code work are still mandatory. 'My buddy did his without a permit' is not a plan.
Bathroom renovation
Swap fixtures in the same spots, no permit. Move plumbing, move walls, or change wiring, and you need one (the electrical goes through ESA).
The line is whether you are moving things or just replacing them. Move a drain and you are in permit land.
Kitchen renovation
Cabinets, counters, flooring – no permit. Move or add plumbing or gas, remove a wall, or rewire – permit (and ESA for the electrical).
Watch the wall. People knock out 'just a small wall' that turns out to be load-bearing, and now you need an engineered beam and a permit after the fact.
Windows and doors
Like-for-like in the same opening, usually no permit. Make the opening bigger, cut a new one, or add a basement/bedroom egress window – yes.
Egress windows are a life-safety item. If you are creating a bedroom in the basement, the window is not optional and the permit is not optional.
Detached or attached garage
Yes. It has a foundation and structure, so it needs a permit and zoning sign-off for setbacks, height, and lot coverage.
Heated or plumbed garage adds mechanical and ESA work. We build a lot of these – the slab and insulation details are where comfort and cost are won or lost. (See our garage permit page.)
Garage conversion to living space
Yes. You are changing the use to habitable space – insulation, heat, ceiling height, egress, fire separation all come into play.
It looks like 'just finishing a room' but the Code treats it as creating living space, which is a higher bar than the garage ever had to meet.
Garden suite / laneway / backyard ADU
Yes – every additional dwelling unit needs a permit. Bill 23 lets most serviced lots have up to three units as-of-right, so you usually avoid rezoning.
Servicing is the real question on these – water, sewer or septic, and setbacks. On a septic lot, the existing system may not be sized for another unit. (See our garden suite pages.)
Demolition
Yes for a house or large structure – you need a demolition permit and utilities disconnected first. Small exempt accessory buildings usually do not.
People forget the disconnects and the demo permit and get a stop-work order on day one. Line it up first.
Swimming pool
The pool itself depends on the municipality and type, but the pool enclosure (fence/gate) permit is almost always required, and the electrical and heater are permitted separately.
The enclosure rule is a drowning-safety law, not a formality. Inspectors take it seriously.
Hot tub
The tub usually does not need a building permit, but the electrical connection goes through ESA, and the deck or structure under it might need one.
If it sits on a raised deck, the deck is the part that needs the permit. And do not let an unlicensed buddy wire 240V to it.
Wood stove or fireplace
Yes – a solid-fuel appliance needs a permit and inspection, usually installed by a WETT-certified installer. Gas appliances go through the gas (TSSA) side.
Your insurer will likely ask for proof of permit and WETT. No paperwork, possible coverage problem if there is ever a fire.
Addition
Yes. More footprint or floor area means a building permit, zoning approval, and usually engineered, BCIN-stamped drawings.
This is a real project, not a weekend job. The foundation tie-in and the existing structure carrying new load are where the engineering shows up.
Second storey
Yes – major structural work. Permit, engineered drawings, and proof the existing foundation and structure can carry the new load.
Half the cost surprise here is discovering the existing house was not built to carry a second floor. Find that out on paper, not halfway through.
Retaining wall
Above roughly 1 m (varies by municipality), yes – and often an engineered design because of the soil loads. Low decorative walls usually do not.
On a slope or near a property line, do not eyeball it. A failed retaining wall is dangerous and expensive.
Solar panels
Rooftop solar usually needs a permit to confirm the roof can carry the load, plus ESA for the electrical. Ground-mount may add zoning and structural review.
The structural check is the point – you are adding weight and wind load to a roof that was designed before solar was on it.
Note: thresholds (shed size, deck height, retaining-wall height) and fees vary by municipality, and zoning is checked separately from the Building Code. Treat this as a straight starting point, then confirm your project with your municipality – or have us confirm it for you.
Not sure if YOUR project needs a permit? Ask the guy who has pulled hundreds.
Tell us what you are planning. We will tell you straight whether it needs a permit, what the building department will want, and where the cost and delay usually hide. Quick paid consult – we scope it on a call and send a secure payment link, so you only pay once you know what you are getting.
Where people get into trouble (so you do not)
“My contractor said no permit was needed.” In Ontario the owner is on the hook – the fines, the after-the-fact drawings, opening finished walls for inspection. Get the requirement confirmed by the municipality, not just the contractor.
“It is just the basement, nobody will know.” Unpermitted finished basements and basement apartments are the classic thing that surfaces at sale, in a title search, or on an insurance claim. It is cheaper to do it right than to legalize it later.
“I will pull the permit after I start.” Starting before the permit is issued is building without a permit – that is a stop-work order, a surcharge (often about 50% of the permit fee), and possibly tearing work out to prove it meets Code.
For the full list of what trips people up – development charges, conservation approvals, the “complete application” clock – see our how to get a building permit in Ontario guide.
Building something that needs drawings? We can design it.
Most permits need proper, scaled, code-compliant drawings – a deck, a garage, an addition, a garden suite, or a full custom home. We design anything from a garden suite to a luxury home and produce the permit-ready set. Tell us what you are building and we will get back to you.
Handy tools and the next pages to read
Want the fee before you apply? Run the Ontario building permit cost calculator. Planning a deck? Use the deck building calculator. Then dig into the specific page for your project below.
Do I need a permit in Ontario: frequently asked questions
Do I need a building permit to build a deck in Ontario?
Usually only if the deck's walking surface is more than 60 cm (about 24 inches) above grade, or it is attached, covered, or serves an exit. A low free-standing deck often does not need one, but the zoning setback still applies – confirm the height threshold with your municipality.
Do I need a permit for a shed in Ontario?
Generally no if the shed is 15 square metres (about 160 sq ft) or smaller and has no plumbing. Larger sheds, or any shed with plumbing or used as living space, need a permit. Zoning setback and lot-coverage rules apply even to permit-exempt sheds.
Do I need a permit to finish my basement in Ontario?
Yes in almost all cases – framing, electrical, often plumbing, egress windows, fire separation, ceiling height and ventilation all require a building permit (and ESA notification for the electrical).
Do I need a permit for a basement apartment?
Yes. A legal second unit needs a building permit and must meet fire separation, egress, ceiling height, smoke/CO alarm and ventilation rules. Bill 23 makes second units broadly permitted by zoning, but the permit and Code compliance are still mandatory.
Do I need a permit to renovate a bathroom?
If you only swap fixtures in the same locations, often no. The moment you relocate plumbing, alter walls, or change wiring, a permit (and ESA for the electrical) is typically required.
Do I need a permit to renovate a kitchen?
Cosmetic work like cabinets, counters and flooring usually does not need a permit. You do need one if you move or add plumbing or gas, remove or alter a wall, or change the electrical layout.
Do I need a permit to replace windows or doors?
Like-for-like replacement in the same opening usually does not. Enlarging an opening, cutting a new one, or adding an egress window does, because it affects the structure and life-safety requirements.
Do I need a permit for a fence in Ontario?
A normal residential fence does not need a building permit but must comply with the municipal fence by-law for height and location. Pool-enclosure fences have their own mandatory requirements.
Do I need a permit to build a garage?
Yes – a detached or attached garage has a foundation and structure and needs a building permit plus zoning approval for setbacks, height and lot coverage. Heated or plumbed garages add mechanical and ESA requirements.
Do I need a permit for a garden suite or laneway house?
Yes – every additional dwelling unit needs a building permit. Under Bill 23 they are allowed as-of-right on most serviced lots (up to three units), so you usually avoid rezoning, but the permit and setback/size/height rules still apply.
Do I need a permit to convert my garage into living space?
Yes. A garage conversion changes the use to habitable space and must meet insulation, heating, ceiling height, egress and fire-separation requirements, all requiring a permit.
Do I need a permit to demolish a building?
Yes – demolishing a house or large structure needs a demolition permit and utilities disconnected first. Small permit-exempt accessory buildings can usually be removed without one.
Do I need a permit for a swimming pool?
The pool structure may or may not need a building permit depending on the municipality, but a pool enclosure (fence/gate) permit is almost always required, and pool electrical and heater work is permitted separately.
Do I need a permit for a hot tub?
The hot tub usually does not need a building permit, but the electrical connection requires ESA notification and the deck or structure supporting it may need a permit.
Do I need a permit to add a wood stove or fireplace?
Yes – a solid-fuel appliance needs a building permit and inspection and is usually installed by a WETT-certified installer. Gas appliances are handled under the gas (TSSA) framework.
Do I need a permit to build an addition?
Yes. Any addition that increases the footprint or adds floor area needs a building permit, zoning approval, and usually engineered, BCIN-stamped drawings.
Do I need a permit to add a second storey?
Yes – it is major structural work requiring a building permit, engineered drawings, and confirmation the existing foundation and structure can carry the new load.
Do I need a permit for a retaining wall?
Retaining walls above about 1 metre (varies by municipality) require a building permit and often an engineered design because of the soil loads. Low decorative walls usually do not.
Do I need a permit to install solar panels?
Rooftop solar usually needs a building permit to confirm the roof can carry the load and that the mounting is sound, plus ESA approval for the electrical connection.
Who is responsible if work is done without a permit – me or my contractor?
In Ontario the property owner is ultimately responsible for permits and for any unpermitted work, including the fines, the after-the-fact drawings, and opening finished walls for inspection – even if a contractor said none was needed.
Reminder: this is general guidance, not a ruling on your specific project. Thresholds and fees vary by municipality, and zoning is separate from the Building Code. Confirm with your municipality – or book a consult and we will confirm it for you.
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