I'm just in the process of dismantling part of a commercial workshop. It's made of concrete sections like a domestic garage,but the panels are 8ft high and 2.5ft wide. I'm going to put it on a dwarf wall,so that I end up with a building that's got 10ft headroom (for my vans) and an overall height of just under 4mtrs. Plan size will be 36ft long x 32 ft wide. All this is allowed under 'permitted development' rights. The only proviso is that you don't cover more than 50% of your garden area. Brilliant,eh ??