What do building control fees cost for an extension?
For a typical house extension in England you’ll pay building control roughly £700 to £1,300 including VAT in 2026. There’s no national figure — every council sets its own scale — and it’s a completely separate charge from your planning application fee.
The short version
Building control is the safety check on your extension: foundations, beams, insulation, fire escape, drainage. Almost every extension needs it, including the ones that are permitted development and need no planning permission at all. The fee for that check isn’t set by central government, so it varies from one authority to the next. What stays roughly constant is the ballpark: a single-storey rear extension usually lands somewhere between £700 and £1,100 including VAT, and larger or two-storey work runs higher.
The thing worth understanding early is that the charge isn’t one payment. With a full plans application it splits in two — a plan charge when you submit your drawings, and an inspection charge when the first site visit happens. Add them together and you have the total. Choose the building notice route instead and you usually pay a single combined fee up front. Either way the money is separate from the £548 you might pay for planning, and separate again from your builder, your drawings and any structural engineer.
Building control charges for an extension, England 2026
| Type of work | Typical total (inc VAT) | How it’s usually charged |
|---|---|---|
| Single-storey extension under 10m² | £700–£850 | Plan charge on application + inspection charge at first visit |
| Extension or loft conversion 10–40m² | £850–£1,100 | Plan charge + inspection charge |
| Extension 40–60m² | £1,050–£1,300 | Plan charge + inspection charge |
| Larger or higher-value builds | £1,200–£2,600+ | Some councils charge on the estimated cost of the work, in bands |
| Regularisation (work already built) | from ~£400 | Single charge, and it’s VAT-exempt |
Figures drawn from published 2025/26 local authority building control charge schedules (Folkestone & Hythe, Sussex Building Control, Havering) and cross-checked across several English councils. Charges are set by each authority under The Building (Local Authority Charges) Regulations 2010, so your council’s exact figure will differ. All include VAT at 20% except regularisation, which is VAT-exempt.
Full plans or a building notice — and why it changes the cost
There are two ways to get building control approval, and the fee is broadly similar either way. What differs is when you pay and how much risk you carry.
A full plans application means you submit drawings and the council checks them before work starts. You pay a plan charge on submission and an inspection charge later, and in return you get a formal approval you can build against — your builder is quoting on details that have already passed. A building notice lets you start sooner with no drawings checked in advance; inspectors visit as the work goes up. It suits small, simple jobs, but if an inspector disagrees with something already built, the cost of putting it right falls on you. For most extensions of any size, full plans is the calmer choice and the small extra effort pays for itself.
Council or a private inspector?
You don’t have to use your local council. Private firms can do building control too, and for a straightforward extension their quote is often close to the council’s. Since the Building Safety Act 2022 took effect — from 6 April 2024, with a short grace period to 6 July 2024 — these firms are called Registered Building Control Approvers and every one has to be registered with the Building Safety Regulator. If you’re quoted by a private inspector, it’s worth a ten-second check that they’re on the register before you sign anything.
One practical wrinkle: if a private inspector stops work for any reason and the job reverts to the council, some authorities charge a reversion fee — commonly 120% of the equivalent building notice charge, and that one isn’t subject to VAT. It’s rare, but it’s the sort of line in a fee schedule that surprises people, so it’s worth knowing it exists.
What the fee doesn’t cover
Building control checks the work; it doesn’t design it. The charge here is only the inspection fee. Your drawings, a structural engineer’s calculations for any beams or foundations, and a party wall surveyor if you’re building near a boundary are all separate and usually cost more than building control itself.
Building control is also not the same as planning permission — different process, different fee, different question. Planning asks whether you may build the thing; building control asks whether it’s built safely. See what a planning application costs for an extension, and what building control actually checks and why it matters when you sell. For the cost of the build itself — the number that dwarfs every fee on this page — there’s a full breakdown of what an extension costs by size and type on our sister site BestBuilders.
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