How Deep Should Fence Posts Go?

One homeowner noticed, as their retaining wall was going in, that most of the posts were at the wrong depth. By then, the job was already well underway.

Post depth is one of those things you can't see once the job is finished. But it decides how long your fence or wall will last.

Why depth matters

• Strength: shallow posts can lean or fall in strong winds.
• Retaining walls: posts hold back tonnes of soil. Too shallow, and the wall can move or fail.
• Soil: sandy or reactive soils often need deeper footings.
• Height: taller fences and walls need deeper posts.

There's no single number that suits every job. The right depth depends on the height, the soil, the product and, for retaining walls, any engineering requirements.

How to spot problems early

1. Ask your contractor how deep the posts will go, before work starts.
2. Watch the first few holes being dug if you can.
3. Ask questions straight away if something looks off. It's far easier to fix before the concrete sets.

How we do it

We set post depth based on your site, not guesswork, and we check it before anything gets covered up.

Want it done right underground too? Call us on 07 2141 7748 or request a free quote.