I am thinking of building a grow room in crawlspace under house. I have an area 10'x10'x6'. Obviously the floor is just dirt with plastic right now. I am thinking of building a grow room within the crawl space with 2x4 framed walls well insulated on the exterior and covering the walls on the inside with some Orca grow film. I don't know if I should frame a floor with lumber or if I can just use a sand or gravel base for the floor? What do you think?