Neighbour's Tree Roots Damaging My Foundation or Sewer Line in Ontario

A slow drain, a damp basement, a new crack in the foundation wall or a heaving walkway can all lead you to a large tree next door. Roots are hard to see and the damage often builds quietly over years, which makes it difficult to know who is responsible and what to do.

This article walks through the practical questions: whether the tree owner may be liable, what evidence helps, whether you can cut roots and how to approach your neighbour. It explains how things generally work, but the outcome depends on your facts, so treat it as a starting point before speaking to a lawyer.

Is the tree owner liable?

How this applies depends on your situation, so it is worth confirming with a lawyer.

Several questions tend to come up. Did you tell the neighbour about the problem, and when? Was the tree healthy or showing obvious trouble? Was the damage to your home caused mainly by the roots, or by something else, such as old pipes, soil conditions or poor drainage? An honest answer to the last one is important, because a neighbour or their insurer will ask it.

Your own home insurance may or may not respond to root damage, since policies differ on gradual damage and on sewer lines. Read your policy and ask your insurer before assuming either way.

Evidence that helps

Root cases often depend on proof of cause and timing. Collecting evidence early, before repairs destroy the physical record, can make a real difference.

• Dated photos and video of the cracks, the tree, the roots if exposed and the surrounding yard.
• A plumber's camera inspection of the sewer line, with a written report and, if possible, footage showing roots in the pipe.
• A written opinion from a structural or foundation engineer about the cause of the damage.
• An arborist's report on the tree's species, size, health and the likely root spread.
• Repair quotes and invoices, kept together with the dates of work.
• A record of every conversation or message with your neighbour about the tree.
• A survey or other proof of where the boundary and the trunk sit, if there is any doubt.

Before repairs begin, ask your professionals to document the damage and, where practical, to keep removed material. Tell your neighbour and your insurer if you are about to do work that will destroy evidence.

Can you cut the roots yourself?

It is tempting to cut roots that cross onto your side, but it is worth slowing down. Heavy cutting can weaken or kill a mature tree, and a tree that fails afterwards can create a worse and more expensive problem. Your neighbour may then say you caused the harm. Cutting may also remove evidence you need.

What you are entitled to do, and the limits, depend on the facts and on where the tree and the roots actually are. Some municipalities have their own rules about trees, so check with yours before any cutting. A lawyer can advise you about your rights in your situation, and an arborist can tell you what pruning a tree can tolerate.

If a root has lifted or cracked a fence on the shared line, the Line Fences Act may help where you and your neighbour cannot agree on repair, because it applies to fences on a shared boundary line in most of Ontario. A municipality can exempt itself by by-law, so check whether the Act applies where you live.

Sorting out the boundary and the sewer line

Two practical questions often get tangled with root damage. The first is where the property line is. If you and your neighbour disagree, a fence-viewers' arbitration will not settle it, because that process does not decide where the boundary is and owners must resolve it themselves. A professional survey is the usual route.

The second is whose pipe it is. How a sewer line is divided between you and the municipality depends on your situation, so ask your municipality or a plumber which section serves your home before you assume a root intrusion is a private matter between you and your neighbour.

What to do next

• Stop and document before repairing anything permanent.
• Get a plumber's, engineer's or arborist's written opinion on the cause.
• Contact your insurer to ask whether the loss is covered and what they require.
• Write to your neighbour calmly, describing the problem and enclosing a few photos, and keep a copy.
• Do not cut major roots until you have advice on the tree and your rights.
• If your neighbour refuses to engage or the cost is significant, speak with a lawyer about your options.

Frequently asked questions