I only brew kits, and I brew in garage and store in shed. The problem with a shed is in the summer it gets too warm and in winter too cold. OK you could use heaters in the winter but in the summer in North Wales the shed really gets too hot, OK to store beer but not to brew beer. I did consider a garden on top of the shed, that would cool it down, but went to garage to brew in instead.
It may seem daft but putting soil on the shed roof with grass or any other plants growing really cools down the shed. This was found out during world war two when they built whole hangers under grass to hide from bombers. Time to think about it is before you build then if required you can build in the support for weight. Other method is a double skin with air gap. Or of course a over hanging tree. But my shed can hit 30 degs in summer so you need some way to cool it for the beer.