Basement gyms in St John’s Wood.
Chelsea · SW3 · Chelsea townhouse, opened up and fitted outCompleted work, photograph
A gym below a St John’s Wood villa, with room for a spa. Westminster sets the rules, not Camden.
What a St John’s Wood gym has to solve.
- NW8
- Detached and semi-detached villas
- Half the garden
- The most a basement may cover
- Open book
- Our own surveyor prices every job
NU Projects is a design and build company in Fulham SW6, founded in 2010. We handle basement gyms and spa rooms in St John’s Wood NW8. A basement runs £450 to £780 a sq ft, construction only. Call 020 7731 6841, and a budget estimate typically follows within seven days.
Here the houses are villas, detached or semi-detached, with proper lawns. A home gym need not be a cramped box. There is space for a lifting hall, a studio and a sauna together.
Westminster counts one storey down from the lowest original floor. The gym can stretch under half the lawn. A margin stays clear along the boundary. A large site with good access may argue for more.
Space lets us split the floor into zones. Each zone gets its own walls, air and lighting. Mature trees can need deep soil above the roof. The roof slab is set to suit.
Our gym is in a Chelsea townhouse, and our steam room is in Kensington. In each case one team designs the room, prices it and builds it.
What the council allows in St John’s Wood.
- Council
- City of Westminster, not Camden. It sets the limits for each gym here.
- Floor area
- Policy 50 gives one storey. On a large site with access, a bigger gym may be argued.
- Boundary
- Half the garden at most. A planted strip stays free all round.
- Trees
- Roof slab depth is set by the planting above. Trees may need up to 1.5 metres of soil.
- Plant
- A spa floor needs its own plant room.
Source: Westminster’s City Plan, January 2026 edition, Policy 50. Read on 2 October 2026. Policies change, so we read them again for your address.
What a basement gym costs in St John’s Wood.
£450 to £780a sq ft, construction only. Our basement band.
£180k to £300kConverting an existing basement. A project total, from our 2026 cost guide.
£500k to £900k+Digging a new basement. A project total, from our 2026 cost guide.
These are two kinds of figure. The band is a rate per square foot, construction only.
The cost guide figures are whole project totals.
Fees, party wall costs, contingency and VAT sit outside them.
What St John’s Wood owners ask about gyms.
In St John’s Wood
- Every service in Hampstead and St John’s Wood
- Basement construction in St John’s Wood
- Luxury refurbishment in St John’s Wood
- Loft conversion in St John’s Wood
- Basement swimming pools in St John’s Wood
- Basement cinema rooms in St John’s Wood
- Basement golf simulator rooms in St John’s Wood
Gyms nearby
- Basement gyms across London
- Basement gyms in Chelsea
- Basement gyms in Kensington
- Basement gyms in South Kensington
- Basement gyms in Holland Park
- Basement gyms in Notting Hill
- Basement gyms in Knightsbridge
- Basement gyms in Belgravia
- Basement gyms in Mayfair
- Basement gyms in Hampstead
- Basement gyms in Fulham
- Marylebone, Bayswater and Maida Vale
- Islington, Highgate and Primrose Hill
Further reading, from the journal
How big can a St John’s Wood basement gym be?
Up to half the lawn at most.
A strip stays clear along the boundary.
Trees also shape the footprint.
Is St John’s Wood in Camden for basement gym rules?
No.
It sits in Westminster.
Camden’s rules apply to Hampstead, to the north.
Can a St John’s Wood villa fit a gym, studio and sauna?
Often yes.
A wide plot allows several zones on one floor.
Each zone has its own walls and air.
Do garden trees limit a St John’s Wood basement gym?
They can.
Deep soil above the roof may be needed.
We plan slab and planting together.
What does a St John’s Wood basement gym cost?
Our basement band is £450 to £780 a sq ft, construction only.
We price the house itself.
Tell us about your home in St John’s Wood.
Your name and one way to reply are enough. It goes straight to the studio.
- Already have an architect or designer? We build to their design. Working with your designer
- An NDA on request, and your home is never published without your consent. How we work in confidence