Hello,
The making of wood racks to me is a very interesting subject. That is because I have been experimenting building them in a variety of ways for some time now. I am always trying to find how to build the strongest rack for the cheapest....or that relates to buying the least amount of lumber !!!! After I build a rack, I always set it up on 6 (8"x16") concrete blocks.....2 on each end and 2 in the middle. My latest style of building a rack is with using (pressure treated) 3@ 10' long 2x4's set up on edge. I make the racks 20" wide, so I cut 2 more pieces of 2x4....17" long and attach them with screws (at each end) between the 2 outside 10' 2x4's. Then screw in from the end pieces to attach the middle 10' piece, it will be cut 3" shorter. Then I cut 2@ 20" pieces and attach them exactly in the middle from end to end, one on top and one on the bottom. That will keep the long pieces from spreading and also gives you an area to place the concrete blocks. Then I attach 2 more 20" pieces to the under side only.....one half way to the end from the center on the left and one on the right. Even though it costs more money, I found that using 3 10' pieces instead of 2, really helps it from bowing down from the weight of the firewood. This was more info than you asked for, but I thought you might be interested. Good luck. If anyone has any other questions about the racks, just send me a private message.
Henry and Wanda