Who is responsible for repairing a retaining wall between two properties?

Generally, if the retaining wall is located entirely on your side of the property line, you are responsible for the cost of its upkeep. That said, there may be other factors in play. 

Right to lateral support

In BC, there’s a general rule of law that says a landowner has the right to have their land be supported by their neighbour’s land, and their neighbour has a duty to maintain that support. The common law calls this the right to lateral support. 

In this case, since the retaining wall is on your property and is holding up your neighbour’s land, you may have a legal obligation to maintain that lateral support. However, there’s an important caveat here. The right to lateral support only applies to land in its “natural state.”

Determining whether land is in its natural state isn’t always straightforward. For example, if your neighbour filled the land above the retaining wall with loose soil, the law may not consider it to be in its natural state. If you and your neighbour can’t agree on whether the land adjacent to the wall is in its natural state, consider getting an opinion from a landscaper or engineer.

If your neighbour damaged the retaining wall

Here’s a second caveat. If your neighbour directly or indirectly caused the damage to the wall, they may be liable to pay for repairs under the law of nuisance. A nuisance occurs when there is an unreasonable interference with the use and enjoyment of someone else’s property. 

Consider this example. An uphill neighbour piled snow to an unreasonable height on the edge of their property, which on melting, flowed onto the downhill neighbour’s property, damaging their retaining wall and property. The court found the uphill neighbour was responsible for the damage under the principle of nuisance (as well as negligence). 

For more on your rights and options, check out this guidance on fences and neighbours.