Reinforced flooring, ventilation, soundproofing and mirror walls, sized to fit your kit, not the other way around.
A garden gym lets you train without a monthly membership or a 20-minute drive. We build them with proper concrete slabs under the floor zone where the rack and platform sit, rubber gym flooring on top, ventilation that actually clears the air, and mirrors on the wall you'd expect them on.
A dropped Olympic barbell from waist height puts roughly 2 tonnes of impact into a 1.2m² area. A standard garden-room floor can't take that repeatedly without damage or sound transmission. So we build our gyms with a reinforced concrete slab zone under the rack and platform area, typically 150mm thick with A252 mesh reinforcement, then a layer of dense rubber gym flooring on top to absorb the bounce and kill the noise.
Ventilation is the detail most garden gym builds get wrong. Training puts significant moisture and heat into a small space; without proper extract, condensation develops on the cold bridges, mould blooms in the corners, and within a year the space smells. We spec quiet mechanical extract with a humidistat trigger, plus either air-con or a deep overhead ceiling fan depending on how seriously you train in summer.
Electrical loads matter more than you'd expect. A treadmill peaks around 2kW; an assault bike with a tablet charging is negligible; a high-end cable machine with an electric weight stack pulls a bit. We run a dedicated circuit sized for the combination of equipment you actually own, and put in one spare 13A circuit for whatever you buy next year.
Slab zones sized for the kit you actually own. No bouncing ceilings.
Extract designed to clear a sweaty session, summer, winter, doesn't matter.
Real mirrors, real flooring, real power. Not a garden shed with a yoga mat.

Yoga, therapy, beauty, music, each built around the acoustic, lighting and hygiene spec you need.

Where footprint and planning allow, fully insulated sleeping spaces with optional shower and WC.

Concrete slab, pad-and-beam or screw pile, specified to the ground you have, not to a one-size-fits-all kit.
Tell us about your project, we'll come back the same working day.