Building control fees and costs in the UK (2026)
3 min
7
September 2026
Key figures in this guide
One-minute decision
What are you trying to work out?
Use the checker first, then turn the result into a clearer brief before speaking to professionals.
Open the checkerBuilding control for a house extension costs £600 - £1,500 in 2026, usually split between a plan check and site inspections. A loft conversion is £550 - £1,100, and a single structural opening £350 - £650. This is separate from planning permission, and you need it even when planning is not required.
You can use your local authority building control or a private approved inspector. Prices are similar; service and turnaround differ.
Building control fees in 2026
| Work | Typical 2026 fee | Notes |
|---|---|---|
| Single structural opening or beam | £350 - £650 | Often a building notice rather than full plans |
| Single-storey extension up to 40 square metres | £700 - £1,200 | Plan check plus 4 - 6 inspections |
| Extension 40 - 100 square metres | £1,000 - £1,700 | More inspections, more plan checking |
| Two-storey extension | £1,100 - £1,900 | Fire and structural checks on both levels |
| Loft conversion | £550 - £1,100 | Fire escape, stair and floor structure checks |
| Garage conversion | £450 - £850 | Damp, floor build-up and insulation |
| Full rewire (electrical) | Included in electrician certificate | Use a Part P registered electrician instead |
| New windows | Included with FENSA or Certass installer | No separate application needed |
| Regularisation (work already done) | 1.5 - 2 times the normal fee | Plus opening up for inspection |
London boroughs and private inspectors in the South East sit at the top of the ranges. VAT is charged on private inspector fees and on most local authority fees.
Full plans or building notice
- Full plans application: you submit drawings and calculations, they are checked before you start, and you get written approval. Slower, but you find problems on paper rather than on site. Best for extensions and anything structural.
- Building notice: you give 48 hours notice and get inspected as you go. Faster and cheaper for simple work, but no approved drawings to fall back on.
What the inspections cover
- 01Excavation, before foundations are poured
- 02Foundation concrete and damp-proof course
- 03Drains, before covering, plus a water test
- 04Floor and roof structure, steelwork and ties
- 05Insulation and air tightness details
- 06Completion, followed by the completion certificate
What else to budget alongside
- Planning application fee, if permission is needed: £328 for a householder application in England in 2026
- Structural engineer calculations: £750 - £2,500
- SAP or energy calculations for large glazed extensions: £250 - £600
- Air tightness or sound testing where required: £300 - £700
- Party wall surveyor, if applicable: £1,200 - £2,500 per neighbour
Why the completion certificate matters
No certificate means questions on every future sale, and possibly a retrospective indemnity policy or regularisation cost. Do not release the builder final payment before the certificate is issued. Keep it with your electrical and gas certificates, the structural calculations and the warranty paperwork.
Who arranges it
Usually your architect or builder submits the application, but the legal duty sits with you as the homeowner. Confirm in writing who applies, who books inspections, and whose price includes the fee, before work starts.
Put it in your brief
Renovome sets out who is responsible for building control, inspections and certificates in your project brief, so it is not a surprise cost at the end. Create your project brief, then compare professionals near you.
Last reviewed: September 2026
Community posts reflect individual experiences and opinions. They are not a substitute for advice from an appropriately qualified professional.