Hey all. I am still in the planning stages for the duck house and I am seriously considering the DLM. Obviously if I choose this route I will have to make the house taller to accommodate the layers of material I use. What is the best substrate to do this with? Straw, shavings, a mixture? I assume you would put this on a bare dirt floor to help with the natural composting of the material? Does anyone out there with ducks employ this system and how do you do it? Any drawbacks? P.S. The welshies are ordered for pick up in mid April. 4 ducks, 1 drake. Getting excited. Thanks, Chris.