Neighbour's Tree Roots Damaging Your Property in Ontario

You find a crack in the foundation, a blocked drain or a heaved driveway, and the likely cause is a large tree next door. It is natural to wonder who pays, and whether you can simply cut the roots yourself.

This article explains the main legal ideas that tend to matter in Ontario: nuisance, boundary trees, municipal tree by-laws, where claims can be brought and how long you have. Your own facts will decide how these apply, so a lawyer can confirm your position.

Why roots become a legal issue

Roots travel well beyond the trunk, and they can lift paving, enter old drain lines and shift soil around footings. Proving that a particular tree caused particular damage is often the hardest part. An arborist, plumber or engineer can usually tell you far more about cause than a lawyer can.

Ontario has no single statute written for this problem that we can point you to here. Instead, the usual starting points are the law of nuisance, rules about boundary trees and your municipality's by-laws.

Nuisance: the usual way to frame a claim

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.

Nuisance looks at the effect on your property rights, not at whether the neighbour's conduct was careless. Unlike negligence, it does not characterize the defendant's conduct. That means a neighbour who never knew about the problem could still face a claim, though how a court weighs all the circumstances will depend on your facts.

• Physical damage, such as a cracked foundation or broken drain pipe, is easier to show than a general annoyance.
• Photos, dates, repair quotes and a written opinion on cause all help.
• Your home insurance may respond to some damage, but that depends on the wording of your policy.

When the tree sits on the boundary

Every tree whose trunk is growing on the boundary between adjoining lands is the common property of the owners of the adjoining lands. Injuring or destroying such a tree without the consent of the land owners is an offence under the Forestry Act.

So if the trunk straddles the line, you cannot treat the tree as the neighbour's alone, and you cannot cut it down or damage it on your own. Courts have not always agreed on how this offence applies between co-owners, so get advice before relying on it against a neighbour or assuming it protects you.

Before you cut any roots

Cutting roots can harm or kill a tree. A local municipality may regulate the injuring or destroying of trees by by-law, and a by-law may require a permit to do so. Whether your municipality has such a by-law, and what size of tree it covers, varies, so check with the municipality first.

A tree by-law does not apply to activities of the municipality or its local boards, and a few other activities are exempt, such as certain work by licensed surveyors and electricity utilities. Those exemptions are narrow and will rarely cover a homeowner's own root cutting.

• Find out whether a municipal tree by-law applies and whether a permit is needed.
• Confirm where the trunk sits and who owns the tree.
• Have an arborist assess whether cutting roots will make the tree unstable.
• Do not injure a boundary tree without the owners' consent.
• Tell the neighbour in writing what you plan to do, and keep a copy.

Some people also ask whether they may trim back to the property line. That is a question of general law that depends on the facts, so talk to a lawyer before trimming if the tree is large, valuable or close to the boundary.

Remedies, courts and deadlines

If talking does not work, a claim for money may go to the Small Claims Court, which hears money claims up to $50,000, not counting interest and costs. Larger claims belong in a different court.

If you want the roots or tree dealt with, a Superior Court of Justice judge 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 also award damages in addition to, or instead of, the injunction.

You are presumed to have known on the day the act or omission happened, unless you prove otherwise. Do not assume the clock only starts when the repair bill arrives.

What to do next

• Photograph the damage and the tree, and note the dates.
• Get a written opinion on cause from an arborist, plumber or engineer.
• Notify your insurer if the damage may be covered.
• Check the municipal tree by-law before any cutting.
• Write to the neighbour describing the damage and asking to talk.
• See a lawyer early, because the two-year clock may already be running.

Frequently asked questions