Indoor Swimming Pool Prices in London & the South East

An indoor pool gives you private, year-round swimming whatever the weather. We design and build reinforced concrete indoor pools across London and the South East: garden pool rooms, pools within the house and basement pools beneath period and new-build homes. One team handles the structure, waterproofing, environmental control and finishes, and every pool carries a 10-year structural guarantee.

Indoor pool types

Garden pool rooms: a pool in a purpose-built outbuilding or pavilion. This is often the most cost-effective route and usually falls under permitted development.
Pools within the house: a pool in a rear or side extension or a ground-floor space, linked to the living areas.
Basement pools: pools beneath existing homes, often combined with a gym, spa, steam room or sauna.
Conversions and wellness suites: turning an existing basement, garage or outbuilding into a pool, or combining pool, spa and hot-and-cold therapy in one suite.

Engineering an indoor pool

Structure: a reinforced concrete shell designed with a structural engineer for your ground conditions.
Waterproofing: multi-layer waterproofing to BS 8102, with joints and penetrations detailed and the shell fill-tested before tiling.
Environmental control: dehumidification, heat recovery and air movement sized to the pool and room.
Plant room: filtration, heating and water treatment in an accessible, ventilated plant room.

Indoor swimming pool price guide — London 2026

Outbuilding pool rooms — pool from £45,000 and pool house from £45,000

The most cost-effective route to an indoor pool in London is a purpose-built outbuilding in the garden — often referred to as a pool room or pool pavilion. Under permitted development rules in England, a garden outbuilding placed at least 5 metres from the main house (in most cases) does not require planning permission. These buildings typically include the pool, a shower and changing area, and basic mechanical services. The structure itself can range from a timber-frame clad building to a contemporary glass and steel pavilion.

Typical prices for outbuilding pool rooms:

Basic 8m × 4m liner pool in a modular outbuilding, wall-mounted dehumidifier, manual cover: from £90,000
8m × 4m concrete tiled pool in a quality outbuilding, ducted dehumidification, auto slatted cover: from £125,000
10m × 4.5m tiled pool in a bespoke pool room, full environmental control, LED lighting, automated filtration: from £175,000

The building cost is separate and depends heavily on the specification and style you choose — timber frame and cladding sits at one end; structural steel and glass at the other.

Indoor pools within the main house — from £90,000

Converting an existing basement, ground-floor space or extension into an indoor pool is one of the most technically demanding builds in residential construction. Waterproofing, drainage, ventilation and humidity control all need to be specified to professional standards — the consequences of getting it wrong are severe.

Typical prices:

8m × 4m liner pool in a rear or side extension, dehumidification, basic filtration: from £90,000
10m × 4m tiled pool in a purpose-built extension, full environmental control, auto cover: from £120,000
10m × 5m pool with infinity edge, automated controls, LED feature lighting: from £150,000

Basement and underground pools — from £125,000

London basement pools are a specialist discipline. Most projects involve pools beneath existing properties, accessed via staircase from the ground floor — often combined with a gym, spa suite or wellness area. Structural coordination with a specialist structural engineer is essential, and the programme is longer than for equivalent outbuilding projects.

Typical prices:

8m × 4m basement pool, structural shell, dehumidification, full M&E: from £125,000
10m × 5m basement pool with spa, automated controls, feature lighting: from £175,000
Full basement wellness complex (pool, spa, steam, sauna): from £250,000+

All basement pool prices are subject to a structural survey. We work with approved structural engineers and can manage the full coordination on your behalf.

These are starting prices. The final cost depends on the size, shape and design of your pool, the finishes and equipment you choose, and access to your site. Every quote is itemised line by line.

Real indoor projects and what they cost: a garden building pool in North West London (£120k), a basement pool and spa in Highgate (£125k), a glass box pool house in Hampstead (£225k) and a natural stone basement pool in Regent's Park (£250k).

What's included in an indoor pool build price?

Structural survey and engineering coordination
Pool design and 3D visualisation
Reinforced concrete shell (RCC or shotcrete) — liner on entry-level outbuilding pools
Multi-layer waterproofing to BS8102 standards
Full mosaic or large-format tiling
Coping and pool deck
Complete filtration and plumbing system
Air-source heat pump or gas heating
Environmental control system (humidity, air temperature, air quality)
Dehumidification (wall-mounted or ducted, to specification)
LED underwater and feature lighting
Full electrical installation to NICEIC standards
Automated pool cover (slatted or roller) — manual cover on entry-level outbuilding pools
Control panel and building management integration
Commissioning and full handover documentation
10-year structural guarantee

Environmental control — the most important indoor pool decision

The most common and costly error in indoor pool builds is underspecifying the environmental control system. An indoor pool generates enormous quantities of water vapour, and without adequate dehumidification and air movement, that moisture will condense on walls, windows and structural elements — causing mould, rot, and eventually structural damage.

Wall-mounted dehumidifiers

The entry-level solution for smaller outbuilding pools and pool rooms. Effective for spaces up to approximately 60–70 m², quiet, and relatively simple to install. Cost: £7,500–£15,000 installed. Suitable for basic outbuilding pools where the space does not need to be fully air-conditioned.

Ducted dehumidification systems

The preferred solution for larger pool rooms, integrated indoor pools and all basement installations. A packaged air handling unit delivers treated, dehumidified air via ductwork throughout the pool space, with full control of temperature, humidity and fresh air exchange. Cost: £16,000–£36,000 installed depending on capacity. This is the specification we recommend for any indoor pool that will be used regularly.

Full pool hall air conditioning

For pools in fully conditioned buildings — typically prime residential projects in central London — an integrated air conditioning and dehumidification system provides year-round climate control across both the pool hall and adjacent spaces. Cost: £50,000+. Required for basement pools integrated with a wider wellness complex.

Pool covers for indoor pools

An automatic pool cover is not optional for an indoor pool — it is essential. A cover dramatically reduces evaporation (and therefore humidity loading on your dehumidification system), retains heat overnight, and improves safety. The cover pays for itself in reduced heating and dehumidification costs within a few years.

Manual thermal cover on roller: £800–£1,500
Automatic slatted polycarbonate cover, recessed housing: £12,000–£25,000
Automatic safety with concealed cassette housing: £15,000–£30,000

Indoor pool running costs

For a heated 8m × 4m indoor pool used daily in London:

Electricity (heat pump, filtration, dehumidification, lighting): £2,500–£5,000 per year
Pool chemicals: £400–£700 per year
Annual service and maintenance: £400–£800 per year
Total: approximately £3,300–£6,500 per year

A quality automatic cover and modern variable-speed pump will reduce this significantly. We include detailed running cost estimates in every indoor pool proposal.

Planning permission for indoor pools

Outbuilding pool rooms under 2.50 metres in height, placed more than 5 metres from the main house, and not covering more than half the garden area generally fall under permitted development in England. Pools within the main dwelling (basement or extension) may require a planning application depending on whether they involve a change to the building envelope. We advise on your specific situation at the survey stage.

Indoor pools require careful planning. We offer a free initial consultation to discuss your site, your specification and your budget — with no obligation to proceed. Call 020 8058 0871 or send us an enquiry online.

Indoor pool price FAQs

How much does an indoor swimming pool cost in London?

An indoor pool in a garden outbuilding starts from about £45,000 for the pool plus £45,000 for the building. A pool inside the main house starts from £90,000, and a basement pool starts from £125,000. Every quote is itemised, including heating, ventilation and dehumidification.

Why does an indoor pool cost more than an outdoor pool?

Most of the extra cost is environmental control. An indoor pool needs dehumidification, ventilation and heating sized for the pool room, plus vapour control and finishes that will not break down in high humidity.

How do you stop condensation and damp in an indoor pool room?

We size ducted dehumidification for the room and design the ventilation and vapour control with the building. For basement pools we add BS 8102 waterproofing so moisture stays where it should.

Do I need planning permission for an indoor pool?

It depends on where the pool goes. A garden outbuilding can often be built under permitted development rules, while extensions and basement pools may need planning consent. We advise on this at the first consultation.

How long does an indoor pool take to build?

Indoor and basement pools take longer than a typical 8 to 16 week outdoor build, because the room, plant and ventilation are built alongside the pool. You get a detailed timeline before work starts.

What guarantee do you give on an indoor pool?

Every concrete pool we build carries a 10-year structural guarantee.

How are payments staged?

Payments are spread across the build in stages. The number and timing of stages depend on the length and size of your project, and we agree the schedule with you before any work starts.

What is the cheapest way to have an indoor pool?

A pool in a garden building is usually the lowest-cost route, from about £45,000 for the pool plus £45,000 for the building. It often falls under permitted development, so no planning application is needed.

How much does it cost to run an indoor pool?

A heated 8m × 4m indoor pool used daily costs about £3,300 to £6,500 a year, most of it electricity for heating and dehumidification. An automatic cover and a variable-speed pump reduce this.

How much does dehumidification cost for an indoor pool?

Wall-mounted units cost £7,500 to £15,000 installed and suit smaller pool rooms. Ducted systems cost £16,000 to £36,000 and are what we recommend for any pool used regularly.