Local costs · London · September 2026
How much does an extension cost in Bromley?
A mid-range 25 m² single-storey extension in Bromley costs about £86,000 to £105,000 including VAT, or £3,400 to £4,200 per m² at London prices. Bromley’s own published charge for building control on a 10 to 40 m² extension is £1,008 (full plans, including VAT): 20% above the typical council (£840). With a measured survey, building regulations drawings, a structural engineer, Bromley’s own building control charge and a 15% contingency, plan for £104,000 to £131,000.
Work out your project in Bromley
Loading the calculator…
Typical prices in Bromley
| Project | Building work | Budget to plan for |
|---|---|---|
| Single-storey extension, 25 m² | £86,000 to £105,000 | £104,000 to £131,000 |
| Double-storey extension, 40 m² | £123,000 to £156,000 | £147,000 to £190,000 |
| Dormer loft conversion, 30 m² | £63,500 to £78,500 | £77,500 to £99,500 |
| Kitchen, medium | £10,600 to £18,800 | £12,200 to £21,500 |
| Bathroom refit | £7,300 to £10,900 | £8,300 to £12,500 |
Building prices in London run about 35% above the UK average outside London. Kitchens and bathrooms vary less from place to place than extensions and lofts.
Building control fees in Bromley
| Work | Charge |
|---|---|
| Extension up to 10 m² (full plans) | £720 |
| Extension 10 to 40 m² (full plans) | £1,008 |
| Larger extension, 40 to 60 m² (full plans) | £1,224 |
| Extension 10 to 40 m² (building notice) | £1,008 |
| Loft conversion up to 40 m² | £1,224 |
| Garage conversion | £648 |
Bromley’s own published charge for building control on a 10 to 40 m² extension is £1,008 (full plans, including VAT): 20% above the typical council (£840). Source: Bromley’s building control charges. The charges apply from 13 October 2025. Bromley publishes its charges without VAT, so we added VAT at 20%.
Private building control firms (registered building control approvers) set their own prices and are often competitive, so it is worth asking one or two for a quote as well. See how Bromley compares with every council we checked.
Notes on Bromley’s schedule
Bromley publishes its own schedule.
Planning
If your extension needs planning permission, a householder application in England costs £548. Many single-storey rear extensions are permitted development and need no application, and a lawful development certificate (£274) confirms it in writing.
Other councils in London
Building control for a 10 to 40 m² extension:
- Havering: £859
- Harrow: £993.83
- Richmond upon Thames: £1,069
- Wandsworth: £1,104
- Hillingdon: £1,122
- Redbridge: £1,320
- Southwark: £1,472.75
- Islington: £1,584
- Camden: £1,875.55
Questions people ask
How much does an extension cost in Bromley?
A mid-range 25 m² single-storey extension in Bromley costs about £86,000 to £105,000 including VAT for the building work, or £3,400 to £4,200 per m², based on London prices reviewed in September 2026. With a measured survey, design, a structural engineer, Bromley’s own building control charge and a 15% contingency, plan for £104,000 to £131,000.
How much is building control in Bromley?
Bromley’s own published charge for full plans approval of a 10 to 40 m² extension is £1,008 (including VAT). The charges apply from 13 October 2025.
How much does a loft conversion cost in Bromley?
A mid-range 30 m² dormer loft conversion in Bromley costs about £63,500 to £78,500 including VAT for the building work, and about £77,500 to £99,500 with fees, Bromley’s own building control charge and a 15% contingency.
Before you get quotes
- How to compare builders’ quotes line by line
- Plan your whole budget, including the costs people forget
- When quotes arrive, check each one against the typical range for your area
Work in Bromley? Firm listings on Estiquote’s map of checked local firms open soon: see what you’ll need. Listing will be free while we build the map, with at least 30 days’ notice before any charge.