Should fence posts be set in concrete or gravel in Metro Vancouver's wet soil conditions?

Fence posts in Metro Vancouver should be set in concrete with a gravel drainage base underneath — this combination provides the structural stability needed for our wet climate while preventing water from pooling around the post base, which is the leading cause of premature rot in our region.

The gravel-and-concrete method is the gold standard for fence post installation in Metro Vancouver's marine climate. Start with a post hole that's 2.5-3 times the width of your post and deep enough for one-third of the total post length to be below grade (minimum 24 inches for a 6-foot fence). Place 4-6 inches of coarse drainage gravel at the bottom of the hole, then set your post on this gravel bed. The gravel creates a drainage layer that allows water to move away from the post base rather than sitting in contact with the wood. Fill the remainder of the hole with concrete, sloping the top surface away from the post to shed rainwater.

Why concrete alone isn't enough in Vancouver's wet conditions: Our region receives over 1,200mm of annual rainfall, with 70% falling between October and March. When posts are set directly in concrete without gravel drainage, water inevitably finds its way down alongside the post and becomes trapped at the concrete-soil interface. This creates a perpetually wet environment around the post base — exactly the conditions that cause cedar and pressure-treated posts to rot. Even naturally rot-resistant Western Red Cedar will deteriorate rapidly when constantly exposed to standing moisture.

Gravel-only installation works in drier climates but isn't recommended for Metro Vancouver's conditions. While gravel provides excellent drainage, it doesn't offer sufficient lateral stability for fence panels that act as wind sails during our winter storms. North Shore properties and elevated areas experience outflow winds that can reach 80-100 km/h, creating tremendous force on solid privacy fences. Posts set only in gravel will gradually work loose and lean, especially in our soft, saturated winter soils.

Proper concrete selection matters significantly in our wet climate. Use high-quality concrete mix designed for fence posts — typically a fast-setting formula that cures properly even in cool, damp conditions. Avoid setting posts in concrete during heavy rain, as excess water weakens the cure and reduces long-term stability. The concrete should extend slightly above grade and be sloped away from the post to direct surface water away from the wood.

Additional Metro Vancouver considerations include using galvanized post anchors or brackets in areas with particularly wet soil conditions, applying end-cut preservative to any cut surfaces on cedar or pressure-treated posts, and considering 6x6 posts instead of 4x4s for gates and wind-exposed locations. The larger posts provide more surface area for concrete contact and greater resistance to lateral forces.

Professional installation is strongly recommended for proper post setting, as mistakes are extremely costly to correct. Improperly set posts will lean, requiring complete removal of concrete footings and reinstallation. The specialized equipment needed for consistent hole depth, post alignment, and concrete placement makes this a job where the cost of professional installation is typically justified by the long-term performance of your fence.

Need help finding a fence contractor experienced with Metro Vancouver soil conditions? Vancouver Fence Builders can match you with local professionals who understand the specific installation requirements for our wet climate.