Garage slab floor heaving

I see this all the time, attached garage, newish homes, slab is heaving in the center and cracked, I have been calling this out because I was saying water is getting between the driveway and the slab, freezing and heaving the slab. Usually there is about a one inch open gap between driveway and slab all the way to the bottom of both, but on this home, the gap was still filled with that fiber stuff they put between the two slabs and it is still (apparently) heaving. so my question is, have I been telling em wrong all this time? Is there something I am missing? Any concrete finishers out there?

That fibre stuff is an expansion joint. It’s designed to isolate the garage “apron” from the driveway slab which is generally unreinforced.
Can’t say about the heaving issue. The minor cracks are common. The gap @ right side, lower garage door also appears to be part of the initial placement of the concrete rather than heaving.
I don’t see a problem here…?

Improper soil compaction or expansive soil conditions then car drives on it equals heaving

A gap under the door seal is a very bad idea in snow country.

Sure would be if we had more information to go on. I don’t see a crack in the slab or how a car driving into a garage slab would cause the concrete to heave upwards. Expansive soil yes if we had more information.
I also don’t see a gap at the left though it may exist as well.

There was no gap on the other side. Plenty of snow and wind here, so the gap will let cold and snow in. There is a ‘bonus’ room over top of the garage, the occupants complained about the upper floor being cold even though the thermostat was set high (about 75 F).
I think I will go with ‘possible improper soil compaction’ on this one.

You do not need to speculate in your report.

Call out the defect and recommend repair.

A different door seal may solve the problem.

The hairline crack isn’t even something i would remark on.


Has anyone taken a steel t- rod used for locating soft soil along plumbing lines and tapped it on the concrete slabs listening and feeling for voids?. Most garage floors here old and new have voids.

Like Mike L stated, it’s best not to speculate. The slab is probably experiencing frost heaving. The water wicks through the gravel that’s under the slab opening of the door, and gets below the frost pour. The door opening area is also the coldest part of the slab, so if you have moisture in the gravel under the slab and it freezes, you will heave up the front edge of the slab every time. This is all assumed speculation.

It’s probably best just to report that the slab is heaving, and move on without speculation.

My guess is it is not heaving at the center but settling at the outer edges instead. When you pack the sand under the slab the area that is the hardest to pack is around the edges. If the guys get lazy the edges do not pack properly. This is obviously just a wag.

Bad pour.

Agreed. Could be heaving, but water would have to get pretty far back into the garage. Poor compaction causing bearing walls to settle to some degree is common. That crack is right next to two re-entrant corners which are high-stress areas, and next to a control joint where the concrete is thinner. Both conditions promote cracking, so you’d be likely to see a crack there even if there was no heaving.