“Every tree whose trunk is growing on the boundary between adjoining lands is the common property of the owners of the adjoining lands.” Ontario Forestry Act (Section 10.2.)
If you live in Ontario and have a tree on your property and its trunk extends across your property-line, then according to the Ontario Forestry Act you have a boundary tree. The tree is therefore “common property.” The important issue: it is the “trunk” which must extend across the property line. The roots and canopies of trees can also cross property lines, but in this case, it is the trunk that is key. In 2013, the Ontario Superior Court provided a legal definition of a tree’s trunk. It is everything between the following two points:
1) from the root-collar to 2) where the first branch appears.
Note: the root-collar is where the roots begin. These may be above ground as well as underground and therefore may not be fully visible. If any part of the tree’s trunk from root collar to first branch—whether it is visible or not—crosses the property line, then it is a boundary tree. A tree’s trunk does not have to cross the property line at any particular point—it just has to cross at any point between the root collar and first branch.
Photos of boundary trees are also available here and can help you discern whether or not your tree is a boundary tree.
The 2013 legal definition of a shared tree is not based on a percentage. Even if 99% of the tree’s trunk grows on one side of a property line, the 1% growing on the other side of the property line still means the tree is a boundary tree and is therefore co-owned.
If a tree grows close to the property line and a property-owner wants to protect or cut it down, he or she should have a professional survey done to clearly establish where the trunk is in relation to the property line. This is not always something that is obvious or visible. It is a potentially expensive legal mistake to claim that the base of a tree (as it appears to the naked eye at ground level) is the determining factor. Once again: it is important to remember that if ANY part of the tree’s trunk crosses the property line it is co-owned.
Hi Hilary,
Gross was sentenced to a fine of $5000 by the JP. However, there is an automatic “victim surcharge” of 25% tacked on by the Province of Ontario so the total amount owing is $6250. Also please correct the maximum fine amount on the welcome page. Cheers.
Scott
Nice site, thank you. Do you know the outcome of the civil suit against Gross and his contractors?
Hi. Thank you for this blog, it’s very helpful. I have a shared willow tree on our shared beach ( shore land) with my neighbour. The tree is protecting the beach from erosion. My neighbour is constructing a shoreline protection, concrete blocks retaining wall, and he asked me if he can take down the tree. I told him that if the tree is mine I wanna keep it. Now he injured the tree and I’m working on getting a surveyor to have a Survey for the shore land. What’s the regulation for shared shore land and trees? Thanks
I am not aware of any special regulations regarding shoreline…but I am not a property expert. Your surveyor may have more information on this. Good luck!
I have a poplar tree in my backyard which is healthy but happens to be leaning towards my rear neighbours house. I do not want to cut down the tree or pay for it to be removed (my neighbour thinks it is my tree but after measuring it looks to be a boundary tree). I am concerned if the tree falls on her house, whose responsibility or insurance will be responsible for the incurred costs and damages? I also cannot find out who I should be contacting to determine if this tree needs to be cut and if I am responsible to pay for it. Who would clarify that the tree is mine or if it is a boundary tree? Thanks.
As far as determining the health and viability of the tree, and options to prevent it from falling, I would suggest hiring a certified arborist and have them come and prepare a report.
The best way to determine a boundary tree is to have a line survey done (by a certified surveyor) and ask them to plot where the tree’s trunk is in relation to the property line. (This is less expensive than a full survey of your property.) If you have an existing survey, then a surveyor can determine whether or not the tree’s trunk crosses the boundary line (but make sure that you are using the legal definition of a tree’s trunk and not just measuring at ground level).
Boundary Trees 
Hi Hilary,
Gross was sentenced to a fine of $5000 by the JP. However, there is an automatic “victim surcharge” of 25% tacked on by the Province of Ontario so the total amount owing is $6250. Also please correct the maximum fine amount on the welcome page. Cheers.
Scott
Nice site, thank you. Do you know the outcome of the civil suit against Gross and his contractors?
Hi. Thank you for this blog, it’s very helpful. I have a shared willow tree on our shared beach ( shore land) with my neighbour. The tree is protecting the beach from erosion. My neighbour is constructing a shoreline protection, concrete blocks retaining wall, and he asked me if he can take down the tree. I told him that if the tree is mine I wanna keep it. Now he injured the tree and I’m working on getting a surveyor to have a Survey for the shore land. What’s the regulation for shared shore land and trees? Thanks
I am not aware of any special regulations regarding shoreline…but I am not a property expert. Your surveyor may have more information on this. Good luck!
I have a poplar tree in my backyard which is healthy but happens to be leaning towards my rear neighbours house. I do not want to cut down the tree or pay for it to be removed (my neighbour thinks it is my tree but after measuring it looks to be a boundary tree). I am concerned if the tree falls on her house, whose responsibility or insurance will be responsible for the incurred costs and damages? I also cannot find out who I should be contacting to determine if this tree needs to be cut and if I am responsible to pay for it. Who would clarify that the tree is mine or if it is a boundary tree? Thanks.
As far as determining the health and viability of the tree, and options to prevent it from falling, I would suggest hiring a certified arborist and have them come and prepare a report.
The best way to determine a boundary tree is to have a line survey done (by a certified surveyor) and ask them to plot where the tree’s trunk is in relation to the property line. (This is less expensive than a full survey of your property.) If you have an existing survey, then a surveyor can determine whether or not the tree’s trunk crosses the boundary line (but make sure that you are using the legal definition of a tree’s trunk and not just measuring at ground level).