For owners planning a pool in a prime home
How Much Does an Indoor Swimming Pool Cost?
Sviatoslav JerdetchiiCEO & Founder of Craftex. Updated , 7 min read
The short answer
Our 2026 indications put an indoor swimming pool from £67,500 inside an existing house and from £85,500 as a basement pool in London. A basement pool with a spa, steam room and sauna starts from £225,000, ex VAT and fees.
- Where the pool goes sets the cost more than its size: a room in the house, a garden building, an extension or a new basement.
- The pool hall and its air handling often cost as much as the pool itself.
- A basement adds excavation, underpinning, waterproofing and ducted dehumidification.
- Fix the design, the plant and the programme before you sign, and keep a contingency of 5% to 10%.
An indoor swimming pool costs from £67,500 inside an existing house and from £85,500 as a basement pool in London, on our 2026 indications. A basement pool with a spa, steam room and sauna starts from £225,000, ex VAT and fees.
Where the pool goes matters more than how long it is. The pool hall, its air and the plant room often cost as much as the water itself. This guide sets out our figures, what moves them and how to keep the budget fixed.
We handle indoor swimming pool construction for prime homes in London and the Home Counties, with the house around the pool. We refurbished the pool at Francis Holland School in 16 weeks, with the school open throughout.
Got a site or drawings? Discuss your project and we reply the same working day.
What an indoor swimming pool costs in 2026
Four settings cover most indoor pools: a room inside the house, a garden pool building, a new pool hall extension or a basement. Each starts from a different figure, because each asks different work of the structure.
| Type of indoor pool | Our 2026 indication | What sets the figure |
|---|---|---|
| Pool inside the existing house (garage, wing or ground-floor room) | From £67,500 | Floor structure, air ducting through the house, finishes |
| Garden pool building | From £75,600 | Size, glazing, height limits, services run from the house |
| New pool hall extension | From £81,000 | Shell, glazing, insulation, roof, planning |
| Basement pool in London | From £85,500 | Excavation, underpinning, waterproofing, ducted air |
| Basement pool with spa, steam room and sauna | From £225,000 | The spa suite, its plant and its finishes |
| Complete pool hall, luxury specification | £345,000 to £501,750 | Size, complexity and the materials chosen |
These are our 2026 indications, construction only, ex VAT and fees. Your fixed figure comes after a survey and the design.
Where a prime London house usually lands
A pool in a prime London house rarely stops at the first row. Stone, mosaic, deck-level edges and a spa suite move it towards the bottom rows. We take on prime home builds from £100,000, so we price the whole room and the house around it, not only the tank.
Not sure which row fits your house? Send us your drawings and the address, and we will tell you what drives your figure.
Cost by pool size, depth and tank type
The pool is priced per square metre of water, and the building around it per square metre of floor. Depth, the tank and the finishes set where you land in each range.
| Element | Our 2026 rate |
|---|---|
| Pool: tank, edges and finishes, per m² of water | £1,350 to £2,700 |
| Pool building, per m² of floor | £720 to £1,800 |
| Air handling, per m³ of pool hall | £157.50 to £225 |
| Pool cover | £900 to £14,400 |
| Glass mosaic or natural stone, extra | £3,600 to £13,500 |
What moves the pool figure
- Size and depth. More water means more structure, more excavation and more heat to keep in.
- Tank type. Concrete or stainless steel: the choice changes the structure, the finishes and the programme.
- The edge. A deck-level overflow edge looks calmer than a skimmer, but needs a balance tank and more plant.
- Finishes. Glass mosaic and natural stone cost more than standard tiles, and take longer to lay.
A worked example at our rates
Take a 10 m × 4 m pool in a 12 m × 5 m pool hall, 2.4 m high, with an automatic safety cover.
| Item | Sum | Our 2026 figure |
|---|---|---|
| Pool building | 69 m² × £1,080 | £74,520 |
| Pool | 40 m² × £1,350 | £54,000 |
| Automatic safety cover | £10,800 | |
| Air handling | 144 m³ × £157.50 | £22,680 |
| Total | £162,000 |
That total is construction only, ex VAT and fees. Finishes, lighting and a spa suite sit on top.
Have a pool size in mind? Put it in your brief when you discuss your project.
The pool hall, plant and dehumidification
A heated pool puts water into the air every hour it is warm. Without the right air handling you get condensation, mould and corrosion in the room and the house around it.
So the air system is a large part of the cost, and the part owners most often under-budget.
| System | Our 2026 rate | Where it fits |
|---|---|---|
| Wall-mounted dehumidifier | £6,750 to £13,500 | A small, simple pool room |
| Ducted air handling unit | £14,400 to £32,400 | Most pools inside a house or a basement |
| Full pool hall air conditioning | From £45,000 | A pool hall joined to a wider spa or living space |
The plant room needs space and a way in
The plant room holds the filters, pumps, heating, dosing and air handling. It needs floor space, ventilation, drainage and a route wide enough to replace a unit later. A plant room with no access route is costly to put right after handover.
Our indoor swimming pool construction team designs the tank, the plant and the air together with the room. The pool specialists work under our contract, so one team answers for all of it. One team delivered the Medusa spa in Knightsbridge, four floors in 17 weeks.
Why a basement pool costs more
A basement pool adds the cost of a new basement to the cost of a pool. That means excavation, underpinning of your walls and often the party walls, propping, waterproofing and spoil removal.
The tank sits below the basement floor, so the dig goes deeper still. Our basement indication includes ducted dehumidification, because the air has nowhere else to go.
Planning and the borough
The Planning Portal says that excavating to create a new basement is likely to need planning permission. Converting an existing basement is unlikely to. Some London boroughs have their own basement policy on depth, extent and construction method.
Our guide to basement conversion cost in London covers underpinning, party walls and borough policies in detail.
Planning a pool under the house? Send us the address and the drawings, and our architects will look at the structure first.
Running costs each year
Running costs depend on the size of the pool, how warm you keep it, how often you swim and the plant chosen. Ask for them at the design stage, because the plant decides most of them.
These are the lines to expect each year.
- Electricity. Heating the water, running the filtration pumps, the air handling and the lighting.
- Water treatment. Chemicals or the consumables for the treatment system chosen.
- Servicing. An annual service of the plant, the air handling unit and the cover.
- Water. Topping up what evaporates and what backwashing uses.
What brings them down
- A cover. It keeps heat in the water and moisture out of the air when the pool is not in use.
- The right air system. Heat recovery in the air handling unit reuses warmth that would otherwise be vented.
- Insulation. Insulating the tank and the pool hall cuts the heat the plant has to replace.
- Variable-speed pumps. They use less power than pumps that run flat out all day.
A cover, heat recovery and insulation cost more at the build. They pay back every year the pool is heated.
Want the plant chosen for lower bills from day one? Discuss your project before the design is fixed.
Keeping the budget fixed
Most indoor pool overruns come from three things: the ground, late design changes, and the pool, the builder and the services under three contracts. Each one is avoidable before you sign.
We advise a contingency of 5% to 10% of the construction cost, depending on complexity. Any change is agreed in writing and priced before the work is done.
Planning a pool building in the garden
A pool or pool building in the garden can be permitted development under Class E. The limits include an eaves height of 2.5 m and a height of 2.5 m within 2 m of the boundary. Together with other outbuildings, it may cover no more than half the land around the house.
Inside the grounds of a listed building it is not permitted.
A glazed pool hall often goes past those limits, so check before you design. Our architects can review your scheme against them: send us your drawings.
Pool and spa projects we have delivered
We refurbished the swimming pool at Francis Holland School in London in 16 weeks. The school stayed open, and the 1,250 m² facility was ready for the new term.
We also designed and built the four-floor Medusa spa in Knightsbridge in 17 weeks. A pool in a house brings both together: wet-room engineering, and finishes that must stay perfect.
For the gym that often sits next to the pool, read our guide to home gym design.
I and my husband are very satisfied with Craftex's service and customer support. We bought a house in Hampstead and wanted to redesign and renovate it. On our initial free consultation with Sviat, we found out that we actually can do loft conversion and rear extension and add value to the property straight away. We worked with the Craftex design team to bring our vision to life and deliver planning approvals. At that time guys started stripping out to save time on the construction programme as we wanted to move in ASAP. We worked with very experienced project director Konstantin who was responsible for all aspects of project delivery from design to construction with a very good eye on details and customer care. We saved a lot of money by having professional advice from the start. Project management and quality at Craftex are at the highest level. Many thanks to Craftex Team.
How we price an indoor pool
We do not publish a fixed price for a pool, because every house and site differs. Our architects draw it and an RICS-qualified quantity surveyor on our team prices it as it is drawn. Pool specialists and spa suppliers work under our contract. About 60% of the labour on our sites is our own.
Got a house, a site or a set of drawings? Discuss your project and we will reply the same working day.
Five checks before you sign for an indoor pool
- A survey of the structure and the ground before the design starts
- The tank, plant room and air system designed together with the room
- A water test of the tank before any tile or stone goes on
- One contract for the pool, the plant, the air and the room
- A fixed programme and a contingency of 5% to 10%
