A fence that would stand for twenty years inland can be flat on the lawn after one winter in Bude. Atlantic gales come straight off the sea, and the usual rule of thumb for post depth is often not enough here. This guide covers how deep to go, what the ground under Bude does to a footing, and the details that keep a fence upright.
The common guide is to bury about a third of the fence's above-ground height, with 600mm as the working minimum for a 1.8m fence. That means a 2.4m post with 600mm in the ground. In a sheltered garden that is usually fine.
On an exposed plot in Bude, treat 600mm as the bare minimum, not the target. A solid 1.8m panel acts like a sail, and all of that load is levered against the bottom of the post. For anything facing west or south-west, or on higher ground around Upton, Maer Down or Widemouth Bay, 750mm is a sensible depth and 900mm is not excessive. That means ordering 2.7m or 3.0m posts instead of the standard 2.4m.
Depth only works if the ground grips the concrete. Around Bude the ground varies a lot over short distances. Much of the town sits on clay over broken shale and sandstone, which holds a post well once you are through the topsoil. Closer to Summerleaze, Crooklets and the dunes, you can hit loose sand that offers very little resistance.
In sandy or made-up ground, go deeper and wider: 900mm deep with a hole around 350mm across is reasonable. In firm shale you may struggle to dig past 600mm by hand, and a tight hole in solid rock at that depth can outperform a deeper one in soft soil. Wet clay is the other thing to watch, because a hole that fills with water overnight needs draining before concrete goes in.
A hole should be roughly three times the width of the post, so about 300mm across for a 100mm post. Put 100mm of gravel or broken stone in the base so water can drain away from the foot of a timber post, then concrete to just above ground level and slope the top so rain runs off.
Post-mix is fine for most garden fences, but on windy sites a properly mixed concrete, well tamped around the post, gives a denser footing. Leave it to cure for at least 24 to 48 hours before hanging panels, and longer if a gale is forecast.
Deeper posts are half the answer. The other half is giving the wind less to push against. Hit-and-miss, slatted or post-and-rail fencing lets air pass through, which cuts the load on each post considerably compared with a solid closeboard or lap panel.
Closer post spacing helps too. Setting posts at 1.5m centres instead of 1.8m means each one carries less. On the most exposed boundaries, a lower fence with planting behind it often lasts longer than a tall solid one.
Check for buried services first. Water pipes, electric cables and drains often run along boundaries, and many are shallower than you would expect in older Bude properties. A cable locator or a quick look at where meters and manholes sit can save an expensive mistake.
Most garden fences up to 2m high do not need planning permission, but the limit drops to 1m next to a road. Rules can be tighter in conservation areas and for listed buildings, so check with Cornwall Council if you are unsure.
It is the minimum, and fine for a sheltered garden with firm ground. On a plot open to the sea or the prevailing south-westerly wind, 750mm to 900mm is a safer depth.
Concrete posts last longest in salty, wet conditions because they do not rot at ground level. Timber works well if it is UC4 treated, sized generously and set on a gravel base for drainage.
Leaning usually means the footing was too shallow or the ground too soft to hold it. Snapping at ground level points to rot in the timber, often made worse by concrete that trapped water around the post.
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