I’ve built and designed a fully functional weight lifting gym sitting at the bottoms of my garden. It’s party piece is it’s internal two level setup! You walk ins at ground level where you’re welcomed by the weight machines and you can step downstairs into the heart of the gym, the free weight area! This is set 1 meter below ground level giving 4 meters of internal head room, whilst sticking to the 2.5m permitted development rules.
Clad in western red cedar and protected with Cuprinol ultimate wood. This was designed and build by myself and friends (gym a partner) and dad. No external help.