How to fix a settled garage floor

[FinallyAGarage]

I will soon be closing on a house with a 3-car garage, appx 25x30. The driveway has sunk an inch or so at the garage, creating a negative grade. The garage floor itself does not feel uneven but has a small crack running half its length and has obviously settled to the point that a structural jack post is loose and the upper structure of the house has sagged. Water drains to the centerline of this floor. I'd like to level the floor with type N morter and install porcelain tile, but want to make sure there won't be future movement. Structural engineer says the negative driveway grade isn't helping by moving water underneath the garage slab. He also mentioned builders of these homes weren't always attentive to soil structure specifically under the garage floor.

So raising the driveway is first on my move-in list. I've called three places. The poly lift place asserts superiority of foam to slurry, which checks out if erosion were an issue. I had assumed foam compresses over time; it's unclear to me whether it does. The other option I suppose is to remove & replace the whole floor. I can only imagine what that will cost. I am looking for a permanent fix so I can lay tile, re-jack the house up, and forget about it. Do you think lifting the driveway and maybe the garage floor will do it?

 

[AC-WC]

My garage had very uneven floors, 2 1/2 car multiple 4X4 pads with limited mesh (all at the bottom). We had a gravel drive and were putting in all concrete. Wanted to tie in the driveway to the garage floor so we wouldn't have the shifting in the winter. Had the garage floor leveled, they drill holes and then pump in some kind of solution. That was 10 yrs ago and still no issues. I would do it again. That's a lot of expense to rip out and re-pour. You're looking at $8-10k for that not including removal.

 

[The Cobbler]

I would say it's pretty hard, and actually impossible to tell from looking at pictures on the internet if a fix is a fix or what.
if the soil has stopped settling, you should be fine with jacking. if it's still settling, well, then it will continue .
I would think that jack post should have been on a footing, so it was bearing on solid ground, and then if the floor settled, the post would stay where it is.
I would look at pouring a footing for the post to rest on and level up as required . then address jacking or filling the concrete for your tile install

 

[Armorpoxy]

We have had clients get excellent results with foam raising by a professional, and no reports of them sinking.