What's the cost difference between having posts set in concrete versus compacted gravel in BC?

Setting fence posts in concrete costs $8 to $12 per post hole, while compacted gravel alone costs $5 to $8 per post hole — a difference of roughly $3 to $5 per post, or $75 to $125 total on a typical 25-post residential fence. That modest cost difference is not the real consideration, though. The real question is which method performs better in BC's wet climate, and the answer is more nuanced than most homeowners expect.

Concrete is the standard in Metro Vancouver and across most of BC for good reason. A properly set concrete footing anchors the post rigidly, resists lateral movement from wind load, and prevents the post from heaving in the seasonal wet-dry cycles that affect BC's clay-heavy soils. For a 6-foot privacy fence in a typical Metro Vancouver yard, each post hole should be 10 to 12 inches in diameter and 24 to 30 inches deep, with 4 to 6 inches of drainage gravel at the bottom, the post centred and plumbed, and concrete filling the hole from the gravel up to 1 to 2 inches below grade level. Two bags of premix concrete (roughly 60 pounds each) per post is standard. The concrete cures in 24 to 48 hours, during which the posts should be braced to prevent movement.

The critical detail that many people miss is the gravel drainage bed under the concrete. In Metro Vancouver's wet climate, this 4 to 6-inch layer of drainage gravel beneath each post is arguably more important than the concrete itself. Without it, water collects at the base of the post where it meets the concrete and has nowhere to drain. The post sits in standing water, and even pressure-treated or cedar posts will rot at this contact point within 5 to 8 years. The gravel allows water to percolate away from the post base, extending post life by years. A concrete footing without a gravel base is actually worse than gravel alone in Metro Vancouver because the concrete creates a bowl that traps water.

Compacted gravel alone (no concrete) is an alternative method where the post is set in the hole, surrounded entirely by gravel that is compacted in layers using a tamping bar. Advocates of this method point out that gravel drains freely around the entire post length, eliminating the water-trapping issue of concrete, and that gravel allows the post to be more easily replaced when it eventually does need to be swapped out. There is merit to both points.

However, gravel-only post setting has significant drawbacks in Metro Vancouver's conditions. First, it provides substantially less lateral rigidity than concrete. A 6-foot solid privacy fence acts as a wind sail, and Metro Vancouver experiences strong winter storms with gusts exceeding 80 km/h — particularly on the North Shore, in elevated areas, and near the waterfront. Posts set in gravel alone are more likely to shift and lean under repeated wind loading. Second, BC's clay soils swell when wet and shrink when dry, creating seasonal movement that can shift gravel-set posts over time. Third, gravel compaction requires skill and patience — each 4 to 6-inch layer must be thoroughly tamped before adding the next — and many installers rush this step, resulting in poor anchoring.

The best practice for BC — and what most experienced Metro Vancouver fence contractors use — is the combination approach: gravel drainage bed at the bottom of the hole, the post set on the gravel, and concrete poured above the gravel. This gives you the best of both methods: the drainage benefit of gravel at the critical post base, and the structural rigidity of concrete for the rest of the post depth. This is the method recommended by most lumber yards and fence material suppliers in the Lower Mainland.

Where gravel-only actually makes sense in BC includes temporary fences that will be moved within 2 to 5 years, fence posts in areas with excellent natural drainage (sandy soil, raised beds), and situations where you anticipate needing to replace individual posts periodically and want easy extraction. Some contractors also use gravel-only for chain-link fence posts with smaller diameters, where the fabric tension provides additional lateral stability.

Where concrete is essential includes all 6-foot or taller solid privacy fences, gate posts (which endure constant lateral force from gate operation), corner and end posts (which have no opposing panel to balance lateral forces), any fence in a wind-exposed location, and any fence on a slope where gravity adds downhill pressure to the posts.

The $75 to $125 extra for concrete on a full residential fence is a trivial amount compared to the $3,000 to $5,000 cost of correcting leaning posts and rebuilding failed sections a few years later. In Metro Vancouver's wet, windy climate, concrete with gravel drainage is the right answer for the vast majority of residential fence installations. Need to discuss your specific situation with an experienced fence contractor? Vancouver Fence Builders offers free matching with local professionals.

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