We work out of a 7x16 enclosed cargo trailer that houses almost everything we need for most jobs.
I have a small storage shed (that I "rent" from a customer), about 10x12 where I store extra ladders, scaffolding, ladder jacks, screw jacks, any special order materials for an upcoming job, as well as misc. leftover supplies such as gun nails, joist hangers, tar paper, shingles, coil stock, etc.
I'm uncertain if I am confusing your "shop" for storage. Do you plan on working out of this shed?