You've done two walkthroughs. The home inspector gave it a passing grade. The listing says the basement was "professionally finished." You remove conditions, close the deal — and three months later, a city building inspector knocks on your door. The basement suite your seller added wasn't permitted. The electrical work isn't up to code. You need to tear it out and redo it, or live with an unresolvable violation on title.
This scenario is more common than most buyers realise. Unpermitted work exists on a significant share of Canadian resale homes — particularly in older urban properties that have been renovated, converted, or modified over multiple ownership cycles. Understanding what building permits are, what they cover, and how to check a property's permit history is one of the most underrated skills a home buyer can have.
What a Building Permit Actually Is
A building permit is a formal authorisation from a municipal government allowing a property owner or contractor to undertake specified construction, renovation, or demolition work. It's not just a piece of paper — it triggers a process: a permit is issued, the work is done, and then a municipal inspector reviews the completed work against the applicable building code before the permit is officially closed.
The permit process exists for three reasons. First, it ensures that structural, electrical, plumbing, and mechanical work meets minimum safety standards. Second, it creates a public record of what work was done and by whom. Third, it protects future owners — and lenders, appraisers, and insurers — by establishing that work was done legally and to standard.
When work is done without a permit, none of these protections exist. The work may meet code, or it may not. There's no inspection record. And the liability for non-compliant work transfers with the property.
What Typically Requires a Permit in Canada
Permit requirements vary by municipality, but the following work categories almost universally require a permit across Canadian jurisdictions:
| Work Type | Why a Permit Is Required | Risk If Unpermitted |
|---|---|---|
| Structural alterations | Affects load-bearing capacity and building integrity | Safety hazard; costly remediation |
| Electrical work | Fire risk from non-compliant wiring | Insurance void; fire liability |
| Plumbing changes | Backflow, leak risk, sewage compliance | Water damage; health risk |
| Basement finishing/suites | Egress, fire separation, ventilation code | Illegal suite; forced removal |
| Additions and decks | Setback compliance, structural loads | Forced removal; title issues |
| HVAC replacement | Combustion safety, efficiency standards | Insurance void; CO risk |
| Window/door enlargement | Structural opening modification | Structural compromise |
Minor cosmetic work — painting, flooring, cabinet replacement — generally doesn't require a permit. But anything that touches structure, mechanical systems, or changes the use of a space almost always does.
How Unpermitted Work Gets Discovered
Buyers often wonder: if work was done without a permit years ago, how would anyone find out? There are several ways it surfaces:
- Home inspection. A good home inspector will flag work that appears non-standard or that deviates from building code in ways consistent with unpermitted execution. They can't certify permit status, but they can raise red flags.
- Permit history check. Many municipalities now publish permit records online. A buyer who pulls the permit history for a property and finds no permits for a clearly finished basement has their answer.
- Insurance underwriting. Insurers sometimes request permit documentation for major renovations as part of the underwriting process. Missing permits can lead to coverage denial or premium loading.
- Refinancing or selling. Lenders and appraisers for subsequent transactions may flag discrepancies between assessed square footage and permitted square footage.
- Neighbour complaint. In some cases, municipalities investigate complaints from neighbours about work that was done without permits.
- Post-purchase permits. A buyer who applies for a permit to do further work on the property may trigger a compliance review that surfaces prior unpermitted work.
How to Check Permit History Before Buying
The best time to check a property's permit history is during your due diligence period — before conditions are removed. Here's how:
- Check the municipal building portal. Most major Canadian municipalities now publish permit records online. Search for the property address and look for permits associated with any visible renovations. Missing permits for finished basement, additions, or mechanical upgrades are red flags.
- Request disclosure from the seller. Ask your agent to request a list of all renovations and associated permit numbers from the seller. In most provinces, sellers are required to disclose known material defects — and a known unpermitted renovation qualifies.
- Use a permit data service. Services like Neighbourly's Building Permits API aggregate permit data across Canadian municipalities, making it possible to get a comprehensive permit history in seconds rather than navigating each municipality's portal separately.
- Have your home inspector specifically flag permit-related concerns. Ask your inspector to note any work that appears to have been done without a permit and to flag deviations from code that suggest non-permitted execution.
- Check if open permits exist. An open permit (one that was issued but never closed because the final inspection was never completed) can be as problematic as no permit at all. It means work was started but never inspected and approved.
What to Do If You Find Unpermitted Work
Discovering unpermitted work during due diligence isn't necessarily a deal-breaker — but it is a negotiating point and a risk that needs to be priced.
Your options include: asking the seller to pull the required permits and complete the inspections before closing (this requires time and cooperation); negotiating a price reduction to cover the estimated cost of remediation; or walking away if the scope of unpermitted work is significant and the seller is unwilling to address it.
What you should not do is proceed without acknowledging the issue. Buying a property with known unpermitted work and doing nothing about it means you own the liability — and if you later try to sell, you'll be in the same position as the seller who just disclosed it to you.