We're finishing our basement (huge dirt crawlspace) and would like to expand it beyond the house, underneath an existing rotten wood deck that is the only exit at the back of the house to the back yard. We're planning on tearing the deck down and building another on top of the new addition.

I'd like to use something other than wood for the deck and will also need it to support the weight of a 2 person hot tub that we just bought.

Any ideas?

Thanks!