Can I attach my fence to my neighbour's existing fence posts in British Columbia?

No, you should not attach your fence to your neighbour's existing fence posts without their explicit written permission — doing so could constitute trespass to property and create legal liability under BC law. Even if the posts appear to be on or near the property line, attaching to someone else's fence structure without consent is legally problematic and practically risky.

The core issue is property ownership. If your neighbour installed their fence posts on their property (even if close to the boundary), those posts belong to them. Attaching your fence to their posts without permission is effectively using their property to support your structure. If the posts are on the property line itself, the situation is more nuanced — but even then, you need agreement from your neighbour before modifying or attaching to their fence.

Under the BC Property Law Act, when a fence sits directly on the boundary between two properties, both owners share responsibility for its maintenance. However, this shared responsibility applies to the existing fence — it does not grant either party the right to unilaterally modify the fence or attach additional structures to it. If you want to connect your new fence to an existing boundary fence, you need your neighbour's agreement.

Practical problems with attaching to a neighbour's posts go beyond the legal concerns. Their posts may not be structurally adequate to support the additional load of your fence — a 4x4 post set to hold a 4-foot chain-link fence on one side is not engineered to also support a 6-foot cedar privacy fence on the other side. The additional wind load alone could cause the post to lean or fail, damaging both fences and creating a dispute about who pays for repairs. In Metro Vancouver's wet climate, drilling into existing posts to attach brackets creates moisture entry points that accelerate rot. And if your neighbour ever decides to remove or replace their fence, your fence goes down with it.

The recommended approach is to install your own independent fence posts set 2 to 6 inches inside your property line, parallel to your neighbour's fence. Yes, this creates a small gap between the two fences — but that gap is preferable to the legal and structural risks of attaching to someone else's posts. The gap also provides air circulation between the fences, which reduces moisture trapping and extends the life of both fences in Metro Vancouver's rainy climate. If the gap bothers you aesthetically, you can fill it with a narrow trim board attached only to your posts.

If your neighbour is willing to share a fence, the better approach is to discuss building one new shared fence together rather than attaching to existing posts. Agree in writing on the fence style, materials, height, cost sharing, and maintenance responsibilities. Many Metro Vancouver neighbours successfully split the cost of a "good neighbour" fence (board-on-board style that looks identical from both sides) installed centred on the property line. Having this agreement in writing protects both parties if either property is sold in the future.

For situations where space is extremely tight — common on Vancouver's narrow 33-foot lots where houses are sometimes only 4 to 5 feet apart — talk to your neighbour about replacing the existing fence with a single new shared fence rather than trying to squeeze two parallel fences into a narrow side yard. A single 6-foot cedar privacy fence centred on the property line, with costs shared, gives both homeowners a better result than two fences crammed into a tight space.

Get it in writing. Whether you're sharing a fence or building independently, a simple written agreement between neighbours about fence location, style, and maintenance avoids future disputes. BC law does not require a formal legal agreement for fence arrangements, but having something in writing — even a signed letter — provides clarity if memories differ later or if either property changes hands.

If you're unsure about your property line location relative to your neighbour's existing fence, invest in a boundary survey before installing your own fence. Vancouver Fence Builders can help you find contractors experienced with tight side-yard installations and shared fence situations across Metro Vancouver.

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