I bought a house where the basement walks out to ground level. On the first floor is a well supported, four foot wide, wrap around deck. On the second floor is a deck that is supported soley by the house and I was told cantilevers out too far. It extends six feet out at the point. I was hoping to build a spiral staircase from the ground up to the second floor deck, with a landing at the first floor deck. Does this sound like a reasonable solution to the support problem?