By The Sauna Company design team · Published 3 Nov 2026
A bespoke home sauna in the UK is a room designed and built on site to fit your exact space, rather than a flat-pack cabin dropped into it. A fully installed traditional Finnish sauna starts from £9,995, excluding VAT and builders' preparatory work. Ventilation, insulation, heater sizing and timber decide whether it is any good.
Key takeaways
- Most homes can take a sauna. Under-stairs voids, spare WCs, loft bathrooms, garages and garden sheds have all become saunas in our projects.
- Size is modest. Typical residential saunas are 1.2–2.4m wide and 1–2.4m deep; around 2.1m high is the sweet spot for performance and energy use.
- Power depends on type. An infrared sauna can run from a standard 13A socket with no drainage. A traditional sauna needs a suitable electrical supply, which your electrician may need to upgrade.
- Ventilation matters most. A poorly designed sauna is, first and foremost, a poorly ventilated one.
- Fit-out is quick. On site, it is typically completed within five working days once your builder has finished the preparatory work.
What does bespoke actually mean?
A bespoke sauna is built in place. We frame it, insulate it, fit a vapour barrier, clad it and build the benches around the dimensions of your room. An awkward ceiling slope or an off-square wall becomes part of the design instead of a problem. Every project we build is a one-off.
The other half of "bespoke" is the engineering. With every sauna design we provide calculations of air volume, heat loss and heater capacity, ventilation and joinery drawings, electrical schematics and an operation manual. Your builder and electrician can then prepare the space correctly before we arrive.
Which type of home sauna should you choose?
Type
Typical temperature
Good fit when
Installed price (ex VAT)
Infrared sauna (Aqua Spazio Radiata)
40–60°C
Only a 13A socket, no drainage, quick install
From £9,995
Standard Finnish sauna (Aqua Spazio Sana)
75–95°C at the ceiling, 5–15% humidity
You want a classic hot sauna with löyly
From £9,995
Premium Finnish sauna (Aqua Spazio Premio)
75–95°C
Frameless glass, dark interiors, app pre-heat
From £14,995
Hybrid sauna (Aqua Spazio Hybrid)
Traditional heat plus ceiling infrared
You want both, in a room that looks fully traditional
From £14,995
Climate-controlled sauna (Aqua Spazio Saunum)
Even heat top to bottom
Single-bench modern layouts, serious sauna users
From £19,995
All prices are fully installed and exclude VAT and builders' work such as partitions, flooring, drainage and electrical supply upgrades.
With only a 13A socket and no drainage, infrared is usually the answer. If the supply can be upgraded, we normally recommend hybrid or traditional, for proper löyly from water on hot stones. Our infrared vs traditional comparison goes into the trade-offs.
How much space do you need?
Less than most people think. A typical residential sauna is 1.2–2.4m wide and 1–2.4m deep, and about 2.1m high is the best height for performance and energy efficiency. Glass panels make a small sauna feel much larger, while a bigger room simply takes longer to heat.
We have built a two-person sauna in a disused WC in Notting Hill, a sauna under a staircase in Clapham and one in the corner of a converted garage in Bromley. If you think your space is too small or too odd a shape, send us photographs and dimensions before ruling it out.
What power, drainage and ventilation do you need?
Power. Traditional heaters need a dedicated supply sized to the heater; an average family sauna uses a 6kW heater. Electrical work in a home in England falls under Part P of the Building Regulations, so your electrician will handle the supply and certification. Sauna lighting must be sauna-rated and wired by a qualified electrician.
Drainage. Not essential for an infrared or traditional sauna, but useful if you want a shower or cold plunge alongside.
Ventilation. This is where most home saunas fall down. A sealed hot room fills with exhaled CO2 quickly. That, rather than a lack of oxygen, is behind the stuffy, dizzy feeling people describe in badly built saunas.
Our primary design goal is effective removal of excess CO2, followed by air circulation that keeps the difference between the upper and lower layers of air as small as possible. Indoor saunas, especially in basements, need more ventilation planning than outdoor ones. Heater manufacturer Harvia, for example, recommends six air changes per hour in a sauna with an electric heater. Read more in our guide to sauna ventilation and CO2.
How a bespoke home sauna is built: timber frame, FF-PIR insulation, foil vapour barrier, ventilated battens and 14mm cladding, with fresh air in low beside the heater and exhaust out on the opposite wall.
Which timber and benches last?
Cladding thickness. Cladding should be at least 14mm thick, the legal minimum in Finland; thinner boards warp. We use 90mm widths for standard builds, 120mm for premium, hybrid, bio and climate-controlled saunas, and 140mm or 160mm for bespoke work.
Timber choice. Aspen and Alder for infrared and standard Finnish saunas; Thermo Aspen for premium builds. Most of the projects in our case studies are clad in Thermo Aspen.
Benches. 28mm thick as standard. Low-density timber such as Western Red Cedar is preferred, because dense hardwoods like oak, ash and beech feel as hot as steel.
Safety details. Doors open outwards, are never lockable and cannot jam. There are no exposed metal nail heads or screws inside, and knots are avoided because they heat up.
Which heaters and controls work best?
We fit HUUM and HARVIA heaters. The HUUM CLIFF appears in more of our case studies than any other heater. It has a natural stone surface, a slim body with small safety distances, and a large stone capacity (HUUM quotes up to 75kg) for mild, long-lasting steam. It won a Red Dot design award in 2021.
The CLIFF is usually paired with the UKU Glass Wi-Fi controller so you can pre-heat from your phone. HARVIA heaters such as The Wall, Cilindro and Legend cover everything from slim wall units for small rooms to bench-embedded and freestanding column heaters, with XENIO Wi-Fi control.
How does installation work?
- Free initial consultation. Photographs, a sketch or a site visit.
- Concept design, then a 3D visualisation once you approve it.
- Design drawings: layout, mechanical services and joinery.
- Preparatory works by your main contractor (partitions, floor tiling, drainage, electrical supply) to our drawings. We visit periodically to place insulation, ventilation and services.
- Fit-out, typically within five working days. The sauna is heated to temperature and cleaned before handover, and you receive a manual with as-installed drawings.
What did we build in Hampstead?
In Hampstead, a large bathroom was converted into a sauna. We built a timber frame, insulated it and fitted a vapour barrier, then clad the room in Thermo Aspen throughout with a 1+1 bench layout.
A frameless glass door and fixed panel bring light in from the bathroom, and concealed LED lighting keeps the room calm. The heater is a HUUM CLIFF 9kW with a UKU Glass Wi-Fi touch pad.
Frequently asked questions
How much does a home sauna cost in the UK?
Our fully installed infrared saunas (Aqua Spazio Radiata) start at £9,995 and standard Finnish saunas (Aqua Spazio Sana) at £9,995. Premium and hybrid builds start from £14,995, and climate-controlled builds from £19,995. All prices exclude VAT and builders' preparatory work. See our home sauna cost guide.
Do I need planning permission for an indoor sauna?
An indoor sauna built within your home is usually internal building work rather than an extension. The electrical work must still comply with Part P of the Building Regulations. Listed buildings and outdoor structures have their own rules, so check with your local authority if either applies.
How long does a home sauna take to heat up?
An average family sauna with a 6kW heater takes up to an hour to reach temperature. Infrared saunas are quicker, typically 15–20 minutes. Wi-Fi controllers let you start the heater before you get home.
What does a home sauna cost to run?
Heating an average family sauna uses about 6kWh, roughly £1.80 at 30p/kWh, and an hour's sauna at home costs about £3.00 in total. Your actual cost depends on your tariff.
How long does a home sauna take to install?
On site, fit-out is typically completed within five working days once your builder has finished the preparatory work.
Talk to a sauna designer
Book a free design consultation, or email photographs and dimensions of your space
to 020 80580871
for an initial assessment. You can also start from our https://www.saunacompany.co.uk/
Planning one for your own home? See our bespoke home saunas page for options and recent projects, or book a free design consultation and we'll talk through your space.
Sources
- GOV.UK — Approved Document P: electrical safety in dwellings. The statutory guidance behind Part P.
- Planning Portal — Electrics: building regulations for electrical work at home. When home electrical work must comply.
- Harvia — Ventilation in the sauna. Six air changes per hour and vent placement for electric-heater saunas.
- HUUM — Three Red Dot award winners. CLIFF heater, Red Dot award 2021.
- HUUM — CLIFF electric sauna heater. Product details and stone capacity.
Planning a sauna of your own? See how our sauna installation service works, from free design consultation to handover.
