Indoor vs Outdoor Hot Tub: Where Should You Install It?
Outdoors is the simpler install. Indoors works when the room is built for it.
Wherever the tub goes, the same questions need an answer: the floor, the air, the drain, the way in, the electrics and the paperwork. Here they are side by side for the same hot tub, indoors on the left and outdoors on the right.
How heavy a full hot tub is
Every litre of water weighs a kilo, so a tub's filled weight is its empty weight plus its water. The Edge manual asks for a level surface that bears that filled weight with bathers inside.1
For these tubs that is 393 kg empty plus 1,503 litres of water, on a footprint of 2.16 m by 2.16 m. That is about 406 kg under every square metre, before anyone gets in.1
Floor and base
Indoors
A level, solid floor that bears the filled weight is the starting point. On a suspended floor, the Edge manual says to contact a structural engineer or contractor before installing.1
Choose a non-porous floor, because a porous one absorbs moisture and is damaged over time, and plan drainage for splashes and water changes.1
Outdoors
Outdoors, the weight sits on a solid, level surface that takes the filled tub and its bathers. The manual rules out curved, soft or sandy ground and blocks, and asks for a professional to check the position before installation.1
Leave at least half a metre of access around all four sides of the tub for servicing, and keep the electrical compartment door easy to open.1
Steam and air
Draining and refilling
Indoors
Plan the drain before the tub arrives. The Edge manual asks for a drainage system around or under the spa for splashes, overflow and emptying, with particular attention indoors.1
Drainage around the tub should also be enough to wash the surrounding floor down, so the room is easy to keep clean.1
Outdoors
Emptying is straightforward: switch the tub off at the supply, remove the drain cap, fit the connector provided and run the water to a place that drains well and is not liable to flooding.1
Drain every three months if you use the tub up to three times a week, and more often with heavier use.1
Getting it in
Electrics
Indoors
An indoor tub sits where people are wet, so the electrician works to the rules for rooms with a bath or shower: Section 701 of BS 7671.3
A registered competent person installs the supply and completes the BS 7671 installation certificate.4 The Edge tubs run on 230 V with a maximum power of 7.7 kW on a dedicated circuit, so hand over the specification early.1
Outdoors
Outdoors, the IET recommends the swimming pool rules, Section 702 of BS 7671.5 The supply has a 30 mA RCD, and the isolator sits outside zone 1, 2 m from the tub's edge.3
Buried cable runs at least 500 mm deep with route marker tape about 150 mm down.5 The dashed line on the plan marks that 2 m. Our hot tub electrical installation guide covers the wiring in more detail.
Planning permission
Indoors
Building regulations cover the ventilation and thermal performance of a room with a hot tub, the same as for an indoor pool.2
A pool hall or tub room added as an outbuilding is generally permitted development within limits, so check the building itself first.2 Your local building control team confirms what applies.
Outdoors
A hot tub in your garden does not normally need planning permission, because it is classed as an outbuilding.6 Listed buildings and conservation areas are the exception, so ask your local planning authority first.
A tub inside a shed-style building falls under separate planning and building control limits.6
Cost
Indoors
The spend sits in the room: a structural check on a suspended floor, ventilation and a dehumidifier if needed, drainage, a non-porous floor, and a way in for a 393 kg tub. Ask a builder to price them together before you choose the tub.1
Running costs are electricity wherever the tub sits. The Edge tubs are compatible with several heat pumps, and the Outdoor Living team can talk you through them on 01482 212322.1
Outdoors
Outdoors, the spend sits in the garden: a solid, level base, a dedicated electrical supply run to the tub, and a clear route for delivery. Ask installers for written quotes covering all three before you commit.
The electrics are the part to get right: a registered competent person installs and certifies the supply,4 and buried cable follows the IET guidance on depth and route marker tape.5
Two Edge hot tubs to plan around
Both Edge tubs share the 2160 × 2160 × 920 mm footprint drawn on the plan above and the same 1,896 kg filled weight, so one plan suits either. Edge is designed and manufactured by Outdoor Living.
Browse the full hot tub range, or read what to consider when buying a hot tub before you choose.
Edge Kensington Hot Tub£7,999
Lounger layout for up to six people, 60 hydrotherapy jets, touchscreen control, heating up to 40°C and ozone water purification. The dedicated lounger gives one seat to stretch out on, with room for the rest of the family around it.
Edge Knightsbridge Hot Tub£7,999
All-seater layout for up to seven people, with the same 60 jets, touchscreen control, built-in Wi-Fi and ozone water purification. Every place is a full seat, which suits a group sharing the tub.
Quick answers
Open a question to read the answer.
Can you put a hot tub indoors?
Yes. The room needs a floor that carries the filled weight, adequate ventilation for the humidity, a drain, a route in wide enough for the tub, and an electrical supply installed and certified by a registered competent person. On a suspended floor, a structural engineer or contractor checks the structure first.
Do you need planning permission for a hot tub?
A hot tub in your garden does not normally need planning permission, because it is classed as an outbuilding. Listed buildings and conservation areas are the exception, so ask your local planning authority first. Indoors, building regulations cover the ventilation and thermal performance of the room.
How much does a hot tub weigh when it is full?
It depends on the model. The Edge Kensington and Edge Knightsbridge weigh 1,896 kg filled, which is 393 kg empty plus 1,503 litres of water, before anyone gets in. The specification of the tub you choose gives its own filled weight.
Does an indoor hot tub need ventilation?
Yes. A heated tub adds humidity to the room, so the Edge manual asks for adequate ventilation to prevent humidity and keep the motor cool, and says a dehumidifier may be needed. Building regulations cover ventilation for a room that houses a hot tub.
Do you need an electrician to install a hot tub?
Yes. A registered competent person installs and certifies the supply. For a tub in the garden, the IET recommends a 30 mA RCD and an isolator outside zone 1, 2 m from the tub's edge.
How much space do you need around a hot tub?
Leave at least half a metre around each of the four sides, so the electrical compartment door opens freely and the tub can be serviced. Outdoors, allow a site of about 3.2 m square for the 2.16 m Edge tubs.
Sources
- Outdoor Living, Edge Kensington and Edge Knightsbridge hot tub manual, 23 June 2026
- Planning Portal, Swimming pools: indoor pools, hot tub housings and sauna cabins, accessed 7 October 2026
- Institution of Engineering and Technology, Wiring Matters issue 86, Hot tubs, July 2021
- HM Government, Building Regulations Approved Document P: Electrical safety, dwellings, 2013 edition
- Institution of Engineering and Technology, Domestic electrical supplies to hot tubs
- Planning Portal, What permissions do I need to install a hot tub in my garden?, accessed 7 October 2026
Paul Margerison
Managing Director & Founder, Outdoor Living
Where a hot tub goes decides how much work the installation takes, so it is worth settling before you choose the tub. This guide lays the two plans side by side.