The family and the challenge
The Kowalski family live in Wieliczka, a town just outside Kraków in southern Poland. Piotr is 45, Marta is 43, and their two teenagers are Kacper (17) and Zosia (15). Four people — four completely different approaches to training.
Piotr — ex-amateur CrossFitter, now focused on strength. Training four days a week: squat, deadlift, press. Marta — cardio and Pilates, weekly yoga, two general fitness sessions. Kacper — football player with a supplementary strength programme focused on legs and core. Zosia — dancer, functional exercises, treadmill.
One gym membership? Nowhere near enough. Four memberships? At £50/month each, that’s £200/month — £2,400 a year. And you still have the scheduling clashes, the commute, and the Saturday morning queue for the cable machine.
The case for their own space was obvious. The question was whether one module could genuinely serve all four.
Why the Premium model?
The Gym Box 11×3 is our flagship — 11 × 3 m of external footprint, 33 m² of usable floor area. The Premium version differs from Standard in three meaningful ways:
1. Enhanced acoustic insulation — additional acoustic layer in the side walls and floor. Loud music at 9 pm doesn’t reach the neighbours.
2. Smart Home package — lighting, air conditioning and electric blinds all integrated and app-controlled. You can set a “morning training” scene: temperature 18°C, warm light, quiet — triggered automatically at 6:30.
3. Higher specification finish — wall panels with twice the lacquer hardness, sports PVC flooring in the cardio zone (instead of standard rubber), stainless steel skirting boards throughout.
Space layout
33 m² divided into two zones with no physical partition — flooring and lighting create the natural boundary:
Strength zone (approx. 20 m²): Rear wall area. 25 mm dark rubber flooring, built for heavy iron.
Cardio and functional zone (approx. 13 m²): Front of the module, facing the panoramic window. Sports PVC flooring — better cushioning for running and movement work. Natural light through the full-width glazing.
Equipment — a complete training studio
Strength zone
➜ 4-station Functional Rig — modular steel frame with attachment points for cables, pull-up bars, TRX and battle ropes. Occupies a 4 m wall run, can be used by 2–3 people simultaneously ➜ 4-post power rack — dedicated for Piotr’s compound lifts. 20 kg Olympic barbell + 400 kg plate set ➜ Rubber-coated dumbbells 2–50 kg — 2 kg increments to 30 kg, 5 kg increments above. Double tiered rack ➜ Kettlebells — 6 weights: 8, 12, 16, 20, 24, 32 kg. Wall-mounted storage rack ➜ 2 benches — flat press bench (Piotr) + adjustable FID (Kacper and dumbbell work) ➜ Olympic lifting mats 50 mm — under the rack and deadlift area
Cardio and functional zone
➜ 2 commercial electric treadmills — orthopaedic cushioning, commercial spec. Piotr and Zosia can run simultaneously ➜ Spinning bike — power meter and Zwift connectivity. Used by Marta and Kacper ➜ TRX — 2 sets — mounted to the Functional Rig. Marta and Zosia use them daily ➜ Medicine balls — 4, 6, 8, 10 kg. Wall-mounted rack ➜ Coordination ladder + agility cones — for Kacper’s football conditioning ➜ Yoga mats — 2 × thick 6 mm mats, rolled storage at the wall
Audio: Sonos system
Piotr trains to heavy metal. Marta prefers calm background music. Zosia’s on pop. Kacper’s on hip-hop. The solution: two Sonos Era 100 ceiling speakers zoned independently. Each person controls their own zone from their phone — no conflict, no compromises.
Services
➜ 5 kW split air conditioning — heating and cooling, optimal air distribution for an active 33 m² ➜ Electric underfloor heating in the cardio zone ➜ LED lighting with colour temperature and brightness control (Smart Home) ➜ Electric blinds on the panoramic window ➜ 8 × 230V sockets + 4 × USB sockets ➜ Mechanical ventilation with heat recovery — with four people training simultaneously, air exchange is not optional
The ROI case
The family were previously spending £200/month on memberships. That’s £2,400 per year — and that’s before fuel, parking and the cumulative hours of commuting.
At a total project cost of £19,800: ➜ Break-even point: just over 8 years on membership fees alone ➜ The gym is operational immediately — no monthly outgoings from day one ➜ The structure adds a permanent amenity to the property
For a UK property context, a quality outbuilding used as a gym adds measurable value to a home — particularly in markets where home gym space has become a genuine selling point post-2020.
Timeline
11 weeks — the longest build in this class, but justified. The Premium module is made to order; the Smart Home package required additional electrical installation work; and the concrete slab for a 33 m² structure needs 28 days’ curing time.
The family ordered in May and took delivery in August — just before the children went back to school.
What the client says
“Each of us trains differently and at different times. Piotr is in there at 6 in the morning, I go at midday, the kids after school. The gym is in use almost all day — and nobody gets in anyone’s way. The Sonos setup was inspired — everyone has their own music. The whole project came in at just under £20,000 and I genuinely think it’s one of the best investments we’ve made. Better value than the garage conversion we were considering.”
Related case studies
➜ Garden Container Gym near Warsaw — Gym Box 11×3 designed around aesthetics and year-round usability ➜ Container Gym in Gdańsk — Gym Box 9×3 with marine-grade specification for a coastal climate
Useful resources
➜ Container Gyms — Full Range — all Gym Box sizes, specs and options ➜ How Much Does a Container Gym Cost in the UK? — detailed cost guide including Premium specification