So my coop is almost finished and I've decided I should use sand and sweet PDZ in the coop. Problem is i've heard you should have atleast 3 inches of it but I feel like it will all fall out the doors and stuff because the only thing around the bottom is a 2x4 so there is only a 1.5 inch lip to keep the sand in. Now I can put boards around everything else but what about the pop doors? If I add a board it will make them alot smaller and they are only 12x12 right now. What should I do? or would it be ok just to not put anything up infront of the pop doors?