My home is on a slab and we have a huge deck. As soon as you walk out of house on the rear is the deck and the first portion fo this deck is covered. We are looking to turn this area into a sun room. My issue is that because we live on a slab, the deck is build right at ground level. The joist underneath are 2x10's and they touch the ground. Not to mentioned that water runs through here. What is the best way to insulate under this portion of the deck?

Thank you!