I am making my coop out of pallets. I am using some old bricks to get the level of the floor right before going up with the walls. Do I have to scrape the grass off and get to dirt? I can't seem to get the pallets that will be the floor level. I assume scrape the grass off and then maybe partialy dig some bricks into the ground to adjust downward if I need to go down less than a brick width? What if I need to go up less than a brick width...what to use for shims?