My barn was plonked on the ground (no foundations) a few hundred years ago. The part I made into the garage slopes down quite a bit, and also had water running down the deep ancient concrete. I used rubber stable matting which has "dimples" on the underside allowing floodwater to run under the mats. It is a good insulator, and has channels on the upside so oil spills etc run down and are cleaned up easily. It is also quite OK to stand on, lie on etc. Altogether worked out well for my purposes. Good luck with your project. Oliver S.
