With a garden gym, the height of the ceiling is an important consideration This gym (with separate shed space) has a vaulted ceiling which makes for a light and airy place in which to work out. If you are planning a garden gym but are concerned that the ceiling height will be too low, fear not. Permitted Development rights allow for pitched roofs on garden buildings to be up to 3.5m at ridge height. As you can see, this results in a generous ceiling height internally. Our client's in Cassiobury, Watford, opted for a vaulted ceiling but if you prefer a flat roof design, you can also use strategically placed rooflights to increase the ceiling height over exercise equipment as needed.