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Building a garden gym
A garden gym saves gym fees and travel time, and gets the weights out of the spare room. But a gym asks more of a building than an office does: a stronger floor, more headroom and much better ventilation.
The short answer: plan more floor space and headroom than you think, ask for a reinforced floor if you'll lift heavy weights, and build in good ventilation. Planning rules are the same as for any garden room, which means the 2.5m height limit near a boundary is often the tightest constraint.1
Size and headroom
Measure your equipment and add space to move around it safely. A treadmill or rowing machine needs clear space behind it, and a squat rack needs room to load plates. Headroom catches people out: overhead presses, pull-ups and skipping all need height. If you want a taller room, it needs to sit at least 2m from every boundary to stay within permitted development.1
The floor and base
Heavy equipment and dropped weights put far more load on a floor than a desk ever will. Tell each company exactly what equipment you'll have and ask how the floor and base are rated for it. Rubber gym flooring protects the floor and deadens noise. For the base itself, see our foundations guide.
Ventilation and condensation
Exercise produces a lot of heat and moisture. Without ventilation, a garden gym gets hot quickly and condensation forms on cold surfaces, leading to damp and mould. Opening windows on two sides, an extractor fan, or an air conditioning unit all help. Our insulation guide explains how to stop condensation.
What it costs
The building costs the same as any garden room of that size and specification, typically £1,200 to £2,500 per m² installed.2 Budget separately for flooring, mirrors, ventilation and the equipment. Use the cost calculator for the building.
Noise and neighbours
Music and dropped weights carry, especially in a room close to a fence. Rubber flooring, acoustic insulation and sensible hours go a long way.
Questions people ask
Do I need planning permission for a garden gym?
Not usually. The same permitted development rules apply as for any garden room.1
How big should a garden gym be?
Measure your equipment and add space to use it safely. Many people find 4m x 3m the useful minimum for a few pieces of kit.
Related guides
Sources
- Planning Portal (England), Outbuildings: mini guide. Permitted development limits for outbuildings.
- MyBuilder, Garden room cost price guide, updated 21 October 2026. UK price ranges for garden rooms, foundations, electrics, plumbing and fees.