My wife wants me to build a deck off the back of our house and we are on a slab. There currently is a 10 x 10 concrete patio that I would build over top and the deck would be approximately 18 x 12. My question has more to do with choosing joists for the deck. I currently have approx 5 1/2" from the concrete patio to the bottom of the patio door. This raises a couple of red flags in my mind and am trying to figure out my options.
My initial idea would be to use 2x4s for joists and have lots of supports (block supports on top of the patio and concrete anchored posts in the area around the patio.
My other question is I would rather not have critters living under the deck. Could I fill in between the joist with drainage gravel before I lay the deck boards?
Thanks for the help