I have 2x6's attached to my wall (it's a pole barn with 8' between poles) and then use 3/4" ply pieces as seperators to slide along the 2x6's. I'm storing over 800 bd/ft of wood along a 16 ft. wall and it's been a pleasure to deal with. Bins can be as wide or narrow as you want them. The 2x6's are every 24' horizontally starting at 4' height.