Indoor Swimming Pools in London — Designed, Engineered & Built

An indoor pool lets you swim every day of the year, in complete privacy, whatever the weather. The Swimming Pool Company designs and builds indoor pools across London and the South East, in garden pool rooms, rear extensions, converted outbuildings and basements. Every project is engineered as a whole — structure, waterproofing, air handling and finishes — and backed by a 10-year structural guarantee.

 

Three ways to add an indoor pool to a London home

• Garden pool room or pavilion — the most cost-effective route. A purpose-built outbuilding holds the pool, a shower and a changing area, from timber-clad to contemporary steel and glass. Many fall under permitted development, so planning permission is often not needed.

• Extension or conversion within the house — a pool in a rear or side extension, or a converted ground-floor space, connects directly to the home. Waterproofing, drainage and ventilation must be specified to professional standards from the start.

• Basement pool — the most private option, and the most technically demanding. We coordinate with your structural engineer and specify waterproofing to BS 8102. See Basement Swimming Pools.

 

Why indoor pools need specialist engineering

An uncovered indoor pool can evaporate one to two kilograms of water an hour. Without proper air handling, that moisture condenses on walls, glazing and structure, causing mould, rot and corrosion. Under-specified dehumidification is the most common and costly mistake in indoor pool builds.

We size every system from a proper moisture-load calculation: wall-mounted units for smaller pool rooms, ducted air handling for larger rooms and every basement. Each pool is paired with an automatic cover, which cuts evaporation by around 70–80% when the pool is not in use.

 

Our indoor pool process

• Consultation and feasibility — send us photos of the space and its rough dimensions. We review access, structure and planning, and give you an initial budget range.

• Design and 3D visualisation — pool size, depth, edge detail, lighting, finishes and plant room layout, all modelled before work starts.

• Structure and waterproofing — a reinforced concrete shell with multi-layer waterproofing to BS 8102.

• Mechanical and electrical — filtration, heating, dehumidification and electrical work to NICEIC standards, designed as one system.

• Finishes and handover — mosaic or large-format tiling, coping, lighting, automatic cover and controls, followed by commissioning, water balancing and handover documentation.

 

Indoor pool prices in London (2026)

• Pool room / outbuilding pool — pool from £60,000, building from £24,000

• Pool within the house (extension or conversion) — from £90,000

• Basement pool — from £100,000 (subject to structural survey)

Typical running costs for a heated 8m × 4m indoor pool used daily are £3,300–£6,500 a year. For a full breakdown, see our Indoor Pool Prices guide.

 

Make it a wellness space

An indoor pool is often the centre of a wider wellness area. Alongside the pool we design and build spa and plunge pools, steam rooms, and gym and changing areas. Traditional Finnish saunas and infrared rooms come through our sister company, The Sauna Company.

 

Frequently asked questions

Do I need planning permission for an indoor pool?
A garden pool room often falls under permitted development, provided it stays within the height, position and garden-coverage limits. Pools in extensions or basements may need an application. We advise on your site at survey stage.

Will an indoor pool cause damp in my house?
Not when it is engineered properly. Correct waterproofing, sized dehumidification and an automatic cover keep moisture in the pool room and out of the house.

Can you work with my architect?
Yes. Most of our indoor projects are delivered alongside the client's architect and structural engineer.

 

Start your indoor pool project

Tell us about your property and what you have in mind. Send a few photos of the space and its approximate dimensions, and we'll come back with initial thoughts and a budget range. Call 020 8058 0871 or send us an enquiry online.