How much does an architect cost for an extension in the UK?
An architect costs £1,200 to £9,000 in the UK, typically around £3,500 for an extension. Prices reviewed June 2026.
Architect fees for a home project are charged either as a fixed fee for the drawings or as a percentage of the build cost for a full service. What you pay depends on how much of the project they run.
Price your architect
Adjust for your job and area to get a range. Nothing is sent anywhere.
Architect cost breakdown
Typical architect costs, by option:
| Service | Typical UK cost |
|---|---|
| Planning drawings only | £1,200 to £2,500 |
| Planning + building regs drawings | £2,500 to £5,000 |
| Full service, design to completion | £4,000 to £9,000 |
| + Measured survey or 3D visuals | add £300 to £900 |
| + Structural engineer's calculations | add £500 to £1,200 |
What's included in the price?
Typical architect prices include:
- Design and drawings for the project
- Drawings for planning permission or building regulations
- Advice on layout, light and materials
- Submitting the planning application where agreed
What changes the price?
The things that move architect prices most:
Drawings only versus a full design-to-completion service
A fixed fee versus a percentage of the build cost
An architect versus an architectural designer or technician
The size and complexity of the project
Does where you live change the cost?
In London, an architect typically costs around £4,600 for an extension, about 30% above the UK average of £3,500. In the North, Scotland and Wales the guide figure is nearer £3,200.
| Region | From | Typical | Up to |
|---|---|---|---|
| Midlands / East (UK average) | £1,200 | £3,500 | £9,000 |
| London | £1,600 | £4,600 | £11,500 |
| South East / South West | £1,400 | £4,000 | £10,500 |
| North / Scotland / Wales | £1,100 | £3,200 | £8,300 |
Guide prices for an extension, scaled with the same regional multipliers as the calculator. Not quotes.
London and the South East run well above the national figures on professional fees.
Common questions
An architect costs roughly £1,200 to £9,000 for a home extension in the UK, typically around £3,500. Planning drawings alone are £1,200 to £2,500, planning plus building regulations drawings £2,500 to £5,000, and a full service from design through to overseeing the build £4,000 to £9,000, or often 8 to 15 percent of the build cost.
Two ways are common. A fixed fee covers a defined package, such as the drawings for planning and building regulations. A percentage of the build cost, usually 8 to 15 percent, covers a full service that runs from design through to inspecting the build. Smaller pieces of work are sometimes charged by the hour. Always get the fee proposal to state which it is and what stages are covered.
Not legally. For a straightforward rear extension, an architectural designer or technician can produce the drawings for planning and building regulations for £1,200 to £3,000, which is often all you need. A full RIBA architect adds design skill and can manage the whole project, which earns its higher fee on complex, unusual or planning-sensitive builds.
For a simple, box-shaped extension, good drawings from a designer may be enough. An architect is worth the higher fee when the site is awkward, the design is ambitious, you are in a conservation area, or you want someone to manage the builders and inspect the work. Match the professional to the ambition of the project rather than paying for a service you do not need.
It depends on the package. A drawings-only fee covers the plans for planning permission and, if included, building regulations. A full service adds detailed design, help choosing and pricing a builder, and site inspections during the build. Architects work in stages, so the fee proposal should spell out exactly which stages are included and which are extra.
Usually the architect prepares and submits the planning application, but the council's application fee is separate and paid by you. Structural engineer's calculations are normally a separate cost of £500 to £1,200 on top, as is the building control charge. When comparing quotes, check what is inside the architect's fee and what you will pay for separately, so you compare like for like.
These are independent guide prices based on typical UK jobs in 2026. Your actual cost depends on your property, spec, access and where you live. Always get at least three written quotes before committing.