I purchased a 15 yr old home a little over a year ago. A previous owner, probably not the last one, had a second story room added where the original deck would have been. The construction was I guess what you would call pole construction. there are three main posts with 48" frost depth footings that hold up a ?ridge beam? or ?rim joist? that holds up the floor. (basically like a deck) the room was built on top of that... everything kosher so far. It apears that they "embelished" the space below on an existing patio slab. Our first winter we noticed nothing, but last year was bad for frost heave here and one corner developed a 1/2 inch hoizontal crack in what I thought was a foundation, but was really just a block placed on top of the patio. and it separated where the patio "connected" to the foundational footing for the post. It has now settled again to its original position with about 1/16 of an inch crack. this happened nowhere else and was only noticed because I went out to grill. There was nothing noticeable inside... no cracks ... nothing.
The walls for the lower portion are actually "hanging" from the floor above, supported I suppose by the posts and the block foundation wall at the yard level. (split entry home... walk out basement) there is a gap between the block that is placed on the patio and the wall. the gap is filled with foam. (I removed drywall to discover this)
Obviously this can pose problems in the future. It didn't our first winter or appearently for at least the last 5... but if it did once it can again.
my question... Is it possible to dig beneath the patio and put in the needed foundational wall around the perimiter of the slab?