Building permits in Canada: when you need one and how to check a home's history

What is a building permit, and who issues it?

A building permit is written permission from your municipality to carry out construction — and a commitment on its side to inspect the work as it goes. In Canada the system has two layers: the code is provincial, the enforcement is local. Each province either writes its own building code (Ontario, BC, Quebec) or adopts an edition of the National Building Code of Canada, and your city, town, or rural municipality applies that code through its building department, headed by a chief building official.

That split explains most of the confusion around permits. Whether a finished basement needs a permit is a provincial-code question with a consistent answer; what the permit costs, which forms you file, and exactly how big a shed can be before it needs one are municipal questions, and the answers genuinely differ from one city to the next. When in doubt, one call or email to your municipal building department settles it — asking is free, and building officials would much rather answer questions than issue orders.

When do you need a building permit — and when don't you?

The working rule: anything structural, anything that changes plumbing or creates new living space, and most additions need a permit; cosmetic work and small detached structures usually don't. The National Building Code's baseline exempts detached accessory buildings of about 10 square metres (roughly 107 square feet), and Ontario raised its threshold to 15 square metres in 2022 — but these are typical figures, and your municipality's bylaw is the one that counts.

What does a building permit cost, and how long does it take?

Permit fees are set municipally, almost always scaled to the size or construction value of the project — so there is no national price, but there is a national shape. A permit for a deck or a shed over the threshold commonly lands in the low hundreds of dollars; a finished basement or a major renovation typically runs from several hundred into the low thousands; additions and new houses scale up from there. Every municipality publishes its fee schedule — check your city's site before you budget.

Timelines follow the same pattern: days to a few weeks for straightforward residential work, longer where the project needs zoning relief or multiple review disciplines. Ontario is the province that puts a number on it — under the Building Code Act, a municipality must issue or refuse a permit for a house within 10 business days of receiving a complete application. Other provinces set no universal clock, but most cities publish current service targets. The clock only ever starts on a complete application: missing drawings are the single most common cause of a slow permit.

How does the permit process work from start to finish?

Every permit in the country follows the same arc: apply, review, inspect, close. The stages look like this.

1. Confirm what you need — call the building department or check its website; verify the zoning bylaw allows what you're planning before you spend money on drawings.
2. Prepare the application — a site plan, construction drawings, and any engineering the project requires. Most cities now take applications through an online portal.
3. Review — plan examiners check the drawings against the building code and zoning bylaw, and send comments if something falls short. Respond promptly; the file waits for you, not the other way around.
4. Permit issued — post the permit card on site and build to the approved drawings. Changing the plan mid-build means amending the permit, not improvising.
5. Inspections — book them at the stages your permit lists, typically footings, framing, insulation and vapour barrier, and final. Each stage must pass before you cover the work.
6. Closure — after the final inspection passes, the municipality closes the permit. That closed status is the goal: it's what a buyer's lawyer will look for years from now.

What happens if you build without a permit?

Unpermitted work rarely blows up on day one — it surfaces later, at the worst possible moments. If the municipality notices work in progress (a neighbour's complaint is the classic route), it can issue a stop-work order on the spot, and fines for building without a permit typically start around double the permit fee and escalate from there. You'll then need a permit to legalize the existing work, which can mean opening finished walls so an inspector can see the framing and wiring you covered up — the renovation you did once gets partially done twice.

The quieter risks cost more. Home insurers can deny or complicate claims that trace back to unpermitted work — a fire that starts in an uninspected electrical renovation is the textbook case. And at resale, unpermitted work is a standing liability: real estate agents ask about it, property disclosure forms in most provinces ask about it directly, and buyers' lawyers routinely search the municipal file. Open permits or obvious unpermitted renovations give buyers grounds to renegotiate, demand fixes, or walk — and a municipality's power to order compliance doesn't expire when the property changes hands.

If you're sitting on unpermitted work now, the fix is straightforward if unglamorous: call the building department and ask about a permit for as-built work. Municipalities process these routinely, and volunteering is treated very differently from getting caught — the earlier you regularize it, the cheaper it is, and the cleaner your file reads when you eventually sell.

How do you find the permit history of a house?

Every permit ever issued against a property sits in a municipal file — the closest thing a house has to a medical record. It shows what was built and when, whether inspections passed, and whether anything is still open. Checking it is standard due diligence before buying, useful leverage before selling, and genuinely interesting for a house you already own: the file often reveals the roof's real age, the year the basement was finished, and renovations no listing ever mentioned.

• Municipal lookup portals — the biggest cities publish permit records online. Toronto posts building application status, Calgary and Edmonton publish permit data through their open-data services (Edmonton's reaches back to 2009), and Vancouver offers permit information too. Coverage and depth vary city to city.
• Ask the building department — in most municipalities you can request a property's permit history directly, sometimes called a compliance report or building file search. Small towns may keep paper files; expect a modest fee and a few days' wait.
• A freedom-of-information request — where routine disclosure isn't offered, provincial FOI/FIPPA processes will get you the file. Slower, but it works everywhere.
• Homeprint's free lookup — enter the address and Homeprint pulls the property's permit history from municipal records in most major Canadian cities, in one place and in plain language.

Whichever route you take, read for three things: permits you'd expect but don't see (a finished basement with no permit on file), permits still open (no final inspection), and the dates — a roof permit from 2015 tells you more about remaining roof life than any listing photo.

Why does permit history matter when buying or selling?

Permit history is the difference between what a house looks like and what it actually is. A home inspection sees present condition; the permit file shows provenance — whether the renovations that make the house worth its price were inspected work or a long weekend's improvisation. For buyers, the two together are far stronger than either alone: pair the inspection with a permit search, and ask the seller's agent directly about any renovation that doesn't appear in the file.

For sellers, the file is worth grooming before listing, not during closing. Close any open permits — often just a matter of booking the final inspection — and regularize old unpermitted work while you control the timeline, because a buyer's lawyer will find the gaps precisely when you have the least room to fix them. A clean, closed permit file is quiet evidence that the house was cared for properly, and it's one of the few forms of resale value you can create with a phone call.