Fence Wind Load Calculator

Most fence panel failures are caused by inadequate post foundations. A standard 1.83m × 1.83m solid panel experiences forces of roughly 1.7-3 kN across typical UK exposure zones (and up to ~5-6 kN in extreme coastal gusts). Posts set only 300-400mm deep in loose soil cannot resist these forces. Proper 600mm+ embedment in concrete collars of at least 300mm diameter is essential for wind resistance.

These are indicative net design pressures on a solid fence (cp,net × qp from BS EN 1991-1-4 + UK NA, cp,net ≈ 1.2). In sheltered urban areas, design for about 0.5 kN/m². Suburban locations with some shelter use about 0.6 kN/m². Exposed rural sites need about 0.75 kN/m², and very-exposed (coastal/hilltop) locations about 0.9 kN/m² — the latter matches the BS 1722-12 palisade design loading. Via the dynamic-pressure relation (qp = 0.613 × v²) these correspond to gust speeds of roughly 64-86 mph. Always err on the side of caution and confirm with a full Eurocode assessment for tall or engineered fences.

For a standard 1.83m fence panel in moderate exposure, posts should be at least 600mm deep in 300mm diameter concrete collars. For exposed sites, increase to 750mm deep with 350mm collars. Very exposed coastal sites may need 900mm+ embedment. The safety factor should be at least 1.5 — meaning the resisting force is 50% greater than the applied force.

Yes, significantly. Permeable fences let wind pass through, reducing the force on posts. A solid close board fence takes 100% of the wind load. As indicative trade estimates this tool applies about 60% loading to hit-and-miss and about 30% to trellis (these are porosity/shelter estimates rather than a single Eurocode factor — BS EN 1991-1-4 only tabulates net pressure coefficients down to a solidity ratio of 0.8). In very exposed locations, slatted or hit-and-miss designs are a sound way to cut wind forces.

For standard domestic fencing, a concrete collar of 300mm diameter is typical. For tall fences (over 1.5m) in moderate exposure, use 350mm. Exposed sites should use 400mm or larger collars. The concrete should be C20 mix (1:2:4) and must fully surround the post. Dome the top of the concrete to shed water away from the post.