I have a raised, concrete patio that measures about 25 x 15 feet. It's quite old about 35 yrs. On the west side (length) it is attached to the house as is the south side. The north end and east end are open to the yard. There is no railing on these 2 sides. The support posts for the awning are attached to the patio. The back door is located in the southwest corner. It is finally beginning to show some wear mostly in the way of cracking. We have had one crack that appears rather deep and over the past several yrs it has gotten larger, now expanding the entire 15 feet (east/west). Over time, one half of the patio has risen (or the other side has sunk) making either side of the crack uneven. The west side of the patio up against the house seems to have also sunken a bit, enough for water to puddle there after a hard rain.Right now we have indoor/outdoor carpeting on it. My question is, is it possible to build a deck over top of the patio, obviously at least a few inches above it, not resting on it. We would have to bury the deck posts in the ground not attached to the concrete patio as it appears to be unstable. We would also have to be sure not to elevate the deck too much or the back door would not clear it. This raised patio was built over top of a ground level slab type patio.