i like to put a layer of sand in roofing instead of insulation. it's fireproof and insulates better. plus it's free. how much weight can ceiling board handle? I find about 15 inches poured into the roof works fine so far. Saves me about $1600 each house built
first sand is very heavy and will probably exceed the loading on the roof and walls the extra reinforcing you would need to make the house SAFE would far outway any savings
