Quote Originally Posted by REP View Post
I have a steel staircase that goes up the side of the house. The first landing is the Kitchen door. I want to be able to walk out the door and two steps up onto the patio. I don't want water to go through to the cars below. So a membrane will be needed.
My concern is what type of Material for the floor Steel or wood. What will hold the load of people ,tables. And all the other stuff that goes with a patio.I'm thinking of a 20x20. For this size span Would I have to have support Columns down the center between the two parked cars? for support. I would rather not if I can get by with out them.

REP
It is possible to free-span a structure of this nature, however you'll definitely want to consult with an architect/engineer to draw up the plans and do the load calculations for you. They will also be able to include code requirements for your jurisdiction.