I want to build a small raised garden bed and then place my prefab coop on the top of it to keep it off the ground. I am using concrete garden blocks for the corners and to hold the wood into the rectangle shape. The coop is 84 by 33…. My question is, how do I measure the wood and allow the room for the blocks…. Do I measure from the center of each block and then cut the wood shorter to total 84”? Don’t want to cut the wood to the wrong size. Thanks.