If you own a semi-detached or row house in Toronto — which describes a significant portion of the city’s housing stock — the party wall is one of the most important things to understand before you renovate.
What Is a Party Wall?
A party wall is the shared wall between your unit and your neighbour’s. In most Toronto semi-detached homes, there’s one party wall running from foundation to roof. In row houses, you have two.
What the Party Wall Agreement Covers
Legally, the party wall structure is jointly owned. Neither owner can do anything that damages or significantly alters the party wall without the other owner’s consent. In Ontario, the Property Law Act and common law govern party wall rights.
Renovation Scenarios That Involve Party Walls
- Opening the wall / removing drywall near party wall: OK as long as you don’t touch the structural/fire assembly of the party wall itself. You can work up to the party wall but not through it.
- Insulating the party wall from your side: Allowed, but check what your neighbour’s wall is made of — adding thermal mass on one side can affect moisture behaviour.
- Adding a beam parallel to party wall: Usually straightforward.
- Adding a beam that bears ON the party wall: Requires neighbour’s consent and possibly a party wall agreement/surveyor.
- Underpinning: If your excavation gets within a certain distance of the party wall footing, you need a party wall surveyor and agreement.
The Practical Advice
Talk to your neighbour before you start any work that could affect the party wall. A conversation upfront is infinitely better than a dispute mid-project.
home.renovation.reviews has threads specifically on party wall situations in Toronto — search “party wall” in the forum.