UPDATED. I want to build a shed for storage but want to have option to maybe convert to an office or studio with bathroom. I am looking at a tuff shed prremier pro studio 10x12 like photo. I am wondering what type of foundarion i need to install. I was at first thinking at minimum a gravel base if storage shes only to keep my budget low. However want to miminuze rework and allow for upgrades. I heard if u do concrete I need have the plumbing and electrical set before pouring. I read an alternative is to do concrete pier so it's more flexibility to add plumbing and electrical in future upgrades. Is that correct? Do the blocks need a full gravel base also? And can I use the metal ones? what should I expect cost. I live in SF bay area CA