I am tying to figure out how to build a deck on top of a concrete porch (about 12x12). The deck that I want will be larger than the porch by three to five feet, but I do not know how to properly "foot" the joists or other supports on top of the the concrete. I am aware of how to pour traditional footings for the over hanging portion, but what should I do to secure this? Any advise and I'll be very grateful. Thanx in advance.