Home / Garden room costs
How much does a garden room cost?
A professionally installed garden room typically costs £1,200 to £2,500 per square metre in the UK, before extras like electrics and foundations.1 The extras are where budgets go wrong, so this guide prices those too.
The short answer: expect roughly £8,000 to £15,000 for an installed modular or flat-pack room, £15,000 to £25,000 for a typical garden office, and £30,000 or more for a bespoke room with a bathroom.1
Garden room cost calculator
Enter a size and choose your extras for a realistic price range, including installation. Figures use published UK price ranges, listed under Sources.
Prices by type
| Type | Typical installed price |
|---|---|
| Self-build kit (materials only) | £1,500 to £2,500 |
| Modular or flat-pack, installed | £8,000 to £15,000 |
| Garden office | £15,000 to £25,000 |
| Brick-built | £15,000 to £30,000 |
| Oak frame | £20,000 to £40,000 |
| Bespoke with bathroom | £30,000 to £60,000+ |
Source: MyBuilder price guide, October 2026.1
The extras that catch people out
Headline prices often cover the building only. Ask every company exactly what's included, because the difference between a shell price and a fully finished room can be £5,000 to £15,000.1
| Extra | Typical cost |
|---|---|
| Ground screw base | £30 to £50 per m² |
| Concrete slab base | £80 to £120 per m² |
| Basic electrical supply | £800 to £1,500 |
| Fully wired room | £2,000 to £3,000 |
| Toilet, shower and drainage | £3,000 to £8,000 |
| Underfloor heating | £500 to £1,500 |
| Lawful development certificate | £129 |
| Planning application | £258 |
Source: MyBuilder price guide, October 2026.1
Two costs that don't show up in price lists: getting materials into your garden if there's no side access, and the length of the cable run from your house. A room at the far end of a long garden can need a much longer, more expensive armoured cable.
Why small rooms cost more per square metre
Doors, windows, electrics, the delivery and the installation team cost roughly the same whether the room is small or large. So the price per square metre usually falls as the room gets bigger, and stepping up a size often costs less than you'd expect. Price two sizes before you decide.
Ways to keep the cost down
- Stay within permitted development. A room under 2.5m tall, behind the house, avoids planning fees and delays. Use the planning checker.
- Keep it under 15m², or 1m from the boundary, to avoid building regulations fees.
- Think hard about plumbing. A toilet can add thousands, mostly in drainage.
- Look at ex-display rooms. Companies sell showroom models at a discount.
- Get at least three quotes on the same specification so you're comparing like with like.
Comparing quotes
When the quotes come in, check each one covers the same things: base, delivery, installation, insulation specification, doors and windows, electrics, internal finish, guttering and removal of waste. Ask how long the guarantee is, who provides it, and whether it survives if the company stops trading.
Questions people ask
How much does a 4m x 3m garden room cost?
At typical installed prices of £1,200 to £2,500 per m², a 12m² room costs roughly £14,000 to £30,000 before extras such as electrics and the base. Use the calculator above for your own mix.1
What is the cheapest way to get a garden room?
A self-build kit is cheapest, at around £1,500 to £2,500 for materials, but you'll still need a base, insulation and a registered electrician.1
Is electricity included in garden room prices?
Often not, or only up to the room. The connection from your house can add £800 to £3,000 depending on what you need.1
Related guides
Sources
- MyBuilder, Garden room cost price guide, updated 21 October 2026. UK price ranges for garden rooms, foundations, electrics, plumbing and fees.