Concreter › Concrete footings and foundations explained
Concrete footings and foundations explained
Footings spread the load of a wall onto the ground. They are hidden, expensive to fix and often inspected by building control, so it pays to understand them before the digger arrives.
Prices on this page are typical UK ranges and estimates as of November 2026. They vary by region, access, ground and the day you ask. Treat them as a way to spot an odd quote, not as a quote.
What footings and foundations do
A foundation carries the weight of a building and spreads it into the ground so the structure does not move. Footings are the concrete in the trench under a wall. What you need depends on the soil, the load, the depth of frost and nearby trees, which is why there is no single price or depth that fits every job. The UK guide we read for concrete grades lists a foundation mix of C20/25 GEN 3 as typical for strip footings, but the engineer or building control officer sets the specification, not a website.
Common types
- Strip foundations. A continuous trench of concrete under walls. Common for houses, extensions and garden walls.
- Trench-fill. Trench filled with concrete almost to ground level, saving brickwork below ground.
- Pad foundations. Separate blocks of concrete under posts or columns.
- Raft. A thick slab under the whole building, used on weaker ground or for light buildings.
- Piles. Deeper elements for poor ground, designed by an engineer.
Depth, ground and trees
The ground decides a lot. Clay shrinks and swells with moisture, and nearby trees draw water from it. That is why a MyJobQuote contributor suggested speaking to a structural engineer where there is clay subsoil and nearby vegetation. Foundations that are too shallow move; those that are over-built waste money. Where there is any doubt, a site visit by a professional costs far less than underpinning.
Building control
Extensions, new buildings and many structural changes must comply with the Building Regulations, whether or not planning permission is needed. In practice that means a building control body will usually inspect the trench before concrete goes in. Ask your builder whether notice has been given and when the inspection is. Do not pour first and ask later. For garden walls and small outbuildings the rules differ, so check with your council or an approved inspector.
What affects the cost
- Trench length, width and depth, which control how much concrete is needed and how much soil has to go.
- Access for a digger, and whether a concrete pump is needed.
- Ground conditions: water in the trench, tree roots, old drains or made ground.
- Reinforcement bars and any engineer's design.
- Inspections and fees.
We do not give a price per metre here because the published figures we found were not reliable enough to repeat. Instead, ask for a written breakdown of excavation, concrete volume and price per m³, and check the concrete price against typical per m³ figures (about £105 to £170 per m³ for delivered ready-mix, plus a minimum delivery charge, in the guide we read).
Example: how much concrete?
A trench 10 m long, 600 mm wide and 750 mm deep filled to the top holds 4.5 m³ (our arithmetic: 10 × 0.6 × 0.75). A trench-fill foundation might be filled only to part of that depth. Always add a small allowance for uneven trench bottoms.
Smaller jobs
Fence posts and small bases are different. For those use postcrete or a basic mix, and see shed and garage bases. If you are choosing someone for foundations, see questions to ask a concreter. This is general information, not structural or legal advice.
Frequently asked questions
How deep should footings be?
It depends on the soil, load and trees. There is no single answer, so ask your structural engineer or building control officer.
Do I need building control for footings?
For extensions and new buildings, yes, in most cases. Check with your council or an approved inspector before you start.
What concrete is used for foundations?
One UK guide lists C20/25 GEN 3 for foundations, but the designer or building control sets the actual mix.