Hello Everyone and Happy New Year
Apologies for a long post, but this only way to explain the problem, which is similar to the one discussed here so I decided to ask for your opinions.
Friend of mine has a similar problem and I am trying to help him getting right people to get the job done.
His house is built on slab on grade, no basement or crawl space. I believe floating slab. On the perimeter of the house slab cracked, disconnected form the foundation and sagged 1-3 inches, depending on the area. Slopes are no longer than 5’, usually less than that. Structural engineer has seen it, couple of foundation guys too. They all concluded that foundation is fine, as of course it is much deeper than the slab and is not sagging.
All of the guys presented couple solutions each. Appropriate thing to do is to jack the slab out, compact grade, insulate it (current one is not insulated) and pour the new one. However, there is a haunch in the slab, and there are walls above it (and not only above it) which support construction so contractor would have to build columns and so. In addition, there is a beautiful bathroom remodeled couple years ago and it would be nice if it could stay (part of slab was redone underneath it). Friend realizes that all of this is doable, however to do it right it would cost relatively a lot of money.
All contractors also mentioned about band-aid solution. Just level the slab and see what happens. There are some indicators that sagging has stopped (it was leveled once and did not sag any more). Leveling concrete should be way cheaper than redoing everything. Friend of mine realizes that it would be a gamble, but is fine with it. A few neighbors did it and the problem did not come back.
So now we get to the root of the question – how to level that slab. Please look at the pictures. They show how much it sagged. This is a maximum, most of the slops are no longer than 4-5 feet (center of the slab is ok, just 2-5 feet around perimeter sagged). Another issue is that slab is covered with tiles cutback residue which most likely contains asbestos. The owner would like to do something like ardex feather finish or similar compound (gypcrete looks ok too, not sure about the cost...), but it says not to exceed ½” of application thickness. We need more in some places. Anyone has any idea how to tackle that problem and more importantly what materials to use in order to achieve described effect? Should some materials be layered? Also, as ceilings are low, we would like to minimize height addition to the existing slab, just to cover residue and level where is sagged. On the top of leveled slab friend would install vapor barrier, and floating engineered hardwood floor, clickable one so easy to remove if needed.
Any help is greatly appreciated.