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Tree Law in Ontario
In heavily populated areas like the GTA, disputes between neighbours regarding trees are common. Disputes typically arise when the branches or roots of a tree on one neighbour’s property (neighbour A) begin encroaching onto their neighbour’s property (neighbour B), causing damage to or interfering with the enjoyment of neighbour B’s property.
Trees and Nuisance Law
In Ontario, the government does not regulate the pruning of trees on private property. As a result, determining who will pay to have a tree pruned is a civil matter. In situations where an individual (neighbour A) refuses to prune the parts of their tree that are encroaching onto their neighbour’s (neighbour B) property, the neighbour whose property is being encroached upon has two options. Neighbour B may sue neighbour A for the cost of having the tree pruned, or to force neighbour A to have the tree pruned. This, however, can be a lengthy and time-consuming process and there is no guarantee that neighbour B will win. The other option is the self-help remedy.
In many cases, the fastest and easiest option to resolve a dispute of this nature is the self-help remedy. The self-help remedy allows neighbour B to pay to have the branches that pass the property line pruned. The self-help remedy may be used even where the tree is not causing damage. If the parts of the tree crossing the property line are a nuisance to neighbour B, they may be removed without notifying or seeking permission from neighbour A. Neighbour B must not, however, trespass onto neighbour A’s property to complete the pruning and must avoid pruning past the property line.
As long as a tree is not considered a “boundary tree” it can be pruned by the neighbor on either side of the property line without permission. A boundary tree is one planted on the property line, so that the trunk grows partially on both properties. Such a tree is jointly owned by both neighbors and cannot be pruned or removed without permission from both parties.
Who is obligated to pay?
If a tree on a neighbour’s property is encroaching onto your property and causing damage, the neighbour may be liable for that damage. An individual will generally be liable for the cost of the damage caused by their tree. For example, if neighbour A fails to maintain their tree and it falls onto neighbour B’s property causing damage, neighbour A will generally be liable for that damage.
Neighbour A is under no obligation, however, to pay for trimming parts of the tree that are not on their property, unless those parts of the tree are unhealthy or pose a safety hazard. Property owners have a positive obligation to maintain all trees on their property and to ensure they are not a hazard.
For example; If neighbor A has a tree, and the branches from the tree are encroaching on neighbor B’s property, neighbor B has the right to trim whatever branches have passed the property line without notifying neighbour A. Neighbor B will be responsible for the arrangements and costs associated with the pruning. If, however, the tree is a safety hazard or poses a risk, neighbour A may be liable for the cost of having it removed so as to ensure no damage occurs to surrounding properties.
If you are involved in a dispute with a neighbour involving a tree, the first step is to notify the neighbor that their tree is causing damage to or interfering with your enjoyment of your property. In some cases, the neighbour who owns the tree may be willing to contribute to or cover the cost of pruning the tree. If the owner of the tree is unwilling to cooperate however, they are legally unable to stop you from completing the pruning at your own expense.
What if the Tree Dies?
In some cases, neighbour B’s pruning of the tree’s branches or roots may damage the tree, causing it to die. While liability surrounding property damage is very fact specific, the Court in Koenig v. Goebel  stated that “there is clear authority for the proposition that a property owner is legally entitled without notice to cut those branches and roots of a neighbour’s Border Tree which extend onto his property or air space although such an action may kill the tree.” The Court later cautioned that this does not mean individuals have an absolute right to destroy their neighbour’s border trees should they begin to extend over the property line. An individual who intentionally kills their neighbour’s tree needlessly may face liability as a result. The decision in Koenig v. Goebel was affirmed in 2013 by the Supreme Court of British Columbia in Demenuk v. Dhadwal .