Another way to do it is using Wiremaid shelving. It comes in various lengths and widths. Attach the back of it to the studs with pipe clamps. An 8' piece, maybe use 4 clamps. Attach the front of it with "adequate" chain attached to ceiling joists. 3 or 4 pieces or as many as you deem necessary. Take a 1/2" or even 1/4" piece of plywood or OSB and lay it on top for a smooth surface. You could have, say, 3 shelves on that wall, all hanging/attached to the chain. Now you have "foldable" shelves. If you want you can fold up the bottom 2 if need arises and use the top shelf
This is what I have in my 10'x12' greenhouse. In the spring all 3 shelves are down and ready for use. And they see a lot of weight. Right now in the late fall I have the 2 bottom ones folded up and seasonal items stored against wall and on the top shelf.
The trick is to attach the shelves in the rear with pipe clamps, so they can be swung up out of the way. If that doesn't matter, then attach them to a horizontal 2x4 in the rear, but using chains in the front is a cheap, simple way for support.
