Party Wall Agreements and Shared Walls in Ontario Semis

If you own a semi-detached or row home, a wall may be shared with your neighbour. When that wall cracks, leaks or needs rebuilding, the question of who must repair it and who pays can become heated.

This article explains how people usually approach these disputes and which legal tools may be available. It does not set out a single rule that decides who pays, because that turns on your documents and the facts.

What a party wall dispute is about

A party wall, or shared wall, is a wall that serves two properties. Disputes typically involve cracking, water getting in, a neighbour cutting into the wall for renovations, or a disagreement over who should pay to repair or rebuild it.

Ontario has no single rule, among the rules covered here, that settles every shared-wall dispute. The answer often depends on what your title documents and any written agreements with your neighbour say.

Start with your documents

• Your deed and the property's registered documents, which may mention shared walls or repair duties.
• Any written agreement made with your neighbour or earlier owners.
• Your survey, if you have one.
• Your home insurance policy, which may respond to some damage depending on its wording.
• Photos, repair quotes and emails showing the problem and when it began.

A lawyer can read these with you and tell you what they likely mean. If there is no agreement, putting one in writing now is often the most practical fix.

Fences are different from walls

If the shared structure is a boundary fence rather than a house wall, there is a specific process. An owner who wants a boundary fence built or repaired may give the municipal clerk notice, in the prescribed form, asking fence-viewers to arbitrate. The award may be appealed to the referee within fifteen days of receiving it. Except for s. 20, the Line Fences Act does not apply to land covered by certain municipal fence by-laws. Do not assume that process also covers a house wall.

Legal routes when talks fail

Private nuisance is an act that indirectly causes physical injury to land, or substantially interferes with its use or enjoyment, where the injury or interference is unreasonable in light of all the surrounding circumstances. It looks at the effect on your property rights, not at whether the other person was careless. Damage to a shared wall from a neighbour's work could be argued this way, depending on the facts.

• A judge of the Superior Court of Justice may grant an interlocutory injunction or mandatory order where it appears just or convenient to do so.
• A court that can grant an injunction may award damages in addition to or in substitution for it.
• The Small Claims Court hears money claims up to $50,000, exclusive of interest and costs.

If you only want a declaration, such as where a boundary lies, there is no limitation period for a proceeding seeking only that declaration with no consequential relief. Otherwise the basic limitation period is two years from the day the claim was discovered, and no proceeding may be started after the 15th anniversary of the act or omission.

What to do next

• Stop and document the problem before repairs change the evidence.
• Talk to your neighbour calmly and propose a written plan for repair and cost-sharing.
• Contact your insurer about coverage.
• Check with your municipality about building permits for wall work.
• Get a contractor's or engineer's opinion on the cause and repair.
• See a lawyer before the two-year period runs out, or sooner if work is under way.

Frequently asked questions