Why combine training and sauna in one module
A gym session followed by 15 minutes of Finnish sauna doesn’t just feel good — it accelerates recovery (lower DOMS, better sleep), and on cold UK winter evenings it turns a 30-minute workout into a proper wellness ritual. Doing it in one container module beats two separate buildings on cost, footprint and planning.
For our Train & Recover package, we put a 35–45 m² Gym Box module into a single unit: 25–30 m² training zone + 6–8 m² Finnish sauna + small changing nook.
Layout — what fits
6×5 m module (30 m² total):
- Training: 20 m² with rack, bench, dumbbells, cardio
- Sauna: 6 m² for 2–3 people
- Vestibule with bench + hooks
7×5 m module (35 m² total):
- Training: 24 m² with full rack + cable + treadmill
- Sauna: 7 m² for 3–4 people
- Shower compartment (cold plunge optional)
Above 35 m² we move into Building Regulations territory (Part L thermal, Part B fire) — but doable, often worth it for households with 2+ users.
Sauna specifications
Standard package includes:
- Harvia Vega 6kW electric heater (commercial-grade, 50,000+ hours)
- Spruce or alder benches (low-resin, less aroma)
- Vapour barrier + foil layer behind cladding
- Internal LED lighting (sauna-rated IP65)
- Thermostat 30–110°C with timer
Wood-fired variants available (Harvia M3) for off-grid installations — adds £900 in setup, removes electrical heater (~9–12 kW load).
Costs
| Item | Cost (£) |
|---|---|
| Module 6×5 with internal partitions | £24,000 |
| Sauna fit-out (heater, benches, stones, controls) | £4,200 |
| Vestibule + cold plunge nook | £1,800 |
| Delivery + installation | included |
| Total turnkey | £30,000–£32,000 +VAT |
Compared to separate gym (£20k) + separate garden sauna (£12k) + groundworks for two buildings: combined module saves roughly £4,000–£6,000 and one round of planning.
Operating costs (UK climate)
Sauna: 6kW heater, 30-min heat-up, 45-min session = 1.5kWh per use. At UK domestic rate of £0.27/kWh = £0.40 per session.
Training zone heating (winter): 1–2 kWh per session at £0.27 = £0.30–£0.55.
Total: ~£1 per training + sauna session. Compared to David Lloyd or Virgin Active membership at £80–£120/month — break-even at ~80 sessions/year.
What about humidity in the training zone?
This is the most-asked question. Answer: complete separation. Sauna has its own vapour barrier, dedicated extraction fan (running on a delay timer after each use), and the wall between zones is a foam-insulated panel with EPDM gasket. Zero moisture transfer to training side — verified on our reference installations in Surrey and the Cotswolds.
Planning permission
The full module sits under Permitted Development Class E in most UK gardens (single storey, ≤2.5 m eaves, ≤4 m apex, ≤50% garden coverage). The sauna inside is treated as an outbuilding fitting — no separate consent needed.
Listed buildings, conservation areas, AONBs and Article 4 areas — full planning may be needed. We supply the design pack for a Lawful Development Certificate application (~£103, 8 weeks) for peace of mind.
What’s next
Free consultation → — we’ll spec your exact requirements, design a 3D layout and quote within 24 hours. Delivery across the UK.
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