Mrs.N, I have been trying to find the best way to store my lumber for over 30 years, and I am still trying. Bill I wish my lumber was as neat as yours. I did build a shelf similar to what your pic is for my small plywood, and it works well. I then I built a stationary cabinet (not on wheels) similar to Rogers, but with slots for my larger sheets of plywood, and I store my rough cut lumber on a set of shelves I bought from a hardware store going out of business. I always thought about building a set of racks that hang down from the ceiling to free up some of my wall space, but never have. The one fault I have is I cannot seem to throw any wood away, so my shelves that looked neat when I started, become a mess. I hope this helps you out.
Mark