Understanding slab foundation split in half

[Milind Shastri]

Hi folks, 

I'm a DIY'er myself and I picked the DIY section so I can learn from the experience of other hand-on folks. I'm trying to understand the approach to recommend to my foundation guy.

I'm working on a BRRR property with a foundation cracked along a straight line. Here's a picture and video explaining it.

It's as bad as this sample image: 

and here's a video of the crack: Video of crack

Wondering if anyone has any ideas of the approach to fix this. I know the foundation guys will be able to lift it up, but I'm trying to understand how to 'join' the cracked parts together so it can make a stable floor and be a reliable rental property.

Thanks!

[Nik Moushon]

@Milind Shastri

You pretty much have only two options here. 

1 - Doing what your foundation guy is suggesting. This is basically jacking up the slab, filling in the voids with grout and then epoxy the the joint once its back in place and the crack is smaller. 

2 - Do the above but instead of epoxy in the crack you saw cut back the slumped slab about 12" from the crack. The drill holes in both sides and epoxy rebar in to tie the slabs together. Then pour new concrete to fill the gap. 

The first option is cheaper but unless your foundation guys can pin-point exactly where the failure occurred you have a change of it happening again. If this is just a small section then its probably not going to happen again but if its the entire length or larger area you have a decent chance of failure again. 

Just an FYI. This is why it is common practice now to have a reinforced slab. So even if there is settling it takes A LOT to actually crack the slab, and near impossible for it to separate without a whole building failure. Obviously older buildings didn't do this.