Dealing with Slab Cracks??????

[steve61]

I'm trying to figure out how to best deal with this.

I've got a 50 year old house slab on grade in So. Calif. I'm in the process of gutting and remodeling the entire house. After pulling up all the carpet I have a couple of problems:

1) Slab itself has lots of dips and peaks. I suspect that within a given room or area I probably have in some areas up to 5/8 or 3/4" elevation variation. Not horrible, but enough you can feel it.

2) Got slab cracks running around. I think most of this was the result of initial setting of the soil a long time ago, as it seems pretty stable as I've been watching over several months. (long before post tension type slabs)

So, my preference is to cover the floor throughout the house with some kind of stone or ceramic tile. But I'm scared to death of laying it on top of this surface and I may just put down hardwood as something lower risk (but I really want stone).

So, my inital thought was to use SLC on this to get it evened out. I may do that (anyway even for the hardwood to give me a more uniform surface). But the cracks and seperations worrying me. Again nothing you would consider structural but mainly kind of ugly (also interestingly enough, all my termite damage came from access through the cracks, even though it was far from a water source).

So assuming the slab isn't heaving around, is SLC safe to put over the cracks? Anything I can do to the slab itself to stablize it such as jack hammering out perpendicular to the bad cracks and dropping in rebar accross the cracks?

I guess could laydown 1/4" or 1/2" CBU, but I'd rather not raise the surface level.

Any thoughts appreciated..
Steve...

[ceramictec]

if it were my floor I would SLC it and cover it with Ditra.

maybe others have a different way, but I think it would be a good way to handle both problems.

[sandbagger]

Steve - well, you already know if you've got any vertical displacement tile is a no-go. Your slab sounds a lot like my 30-yr old AZ slab. Mostly I used a membrane over the cracks, but one room was a little more severe. Wife was worried so we had a foundation guy take a look. He didn't think the problem was severe, but did recommend "stitching" with carbon fiber, and said I could do it myself. I did some research and found something called Torque-Lock that I liked better and am currently in the process of installing. It's prolly overkill, but my other half feels better so it's OK.

[Davestone]

I would think the Torque Lock would just cause the slab to crack at the rods if there was any great movement,especially as narrow as they are,but i could be wrong.I would say being in Calif. with the previous slab movement i would pass on a stone install myself.

[ceramictec]

silly thing I did when I was just in the trade (1990) was to hammer nails (concrete nails) into the cracks every 2'.
back then I didn't know or understand crack suppression so I did this after a super told me about it.
never had the tile crack. I'm sure the crack couldn't close, it could probably open further.
glad I learner about sheet membranes.

[cx]

Never used anything like that Torque Lock, Art, but I gotta agree with Stoner on this one. Just gotta believe if that slab takes a mind to move a little bit again it's just gonna crack again where it's doweled into the slab.

I've seen lots and lots of repairs with the high-dollar epoxy stuff that's advertised as "stronger than the concrete," too, and, of course, it is stronger than the concrete in tensile strength. So when the slab moves a little again, it just pops a new crack right next to the epoxy repair.

But installing something that makes you spouse happy gotta be considered a really good repair on at least one level.

Whatever you elect to do to flatten/level that slab, Steve, I think I'd wanna give a serious look at NobleSeal CIS installed with their special pookey if I were set on having tile on that floor.

My opinion; worth price charged.

[Trask]

I know a builder that did a "homeade stich" job with rebar and epoxy. about a ft. on either side of the crack.He never got around to tiling the slab as I told him "why don't you give it a season" and see how that works..it did a heck of a job too.It held the crack tight where he repaied it. But the next summer it cracked almost exactly 20' away..

[steve61]

Thanks guys for the good thoughts, gonna have to think about this one for a while. I think if I attempt stone/tile using a membrane of some type is the way to go after leveling with SLC.

As far as stitching the crack I guess I heard about what I expected. Sure I can probably use one of the products or methods, but if the slab wants to move, its going to find someplace to crack.

[sandbagger]

Nothing will prevent a slab from cracking if there is enough movement, and the people who do this type of repair work or sell the materials (like Torque-Lock) make that perfectly clear. As pointed out, cracks can happen adjacent to the repair area if there is enough stress (the repair is now the strong point, not the weakest).

Sorry if I gave the impression otherwise. I'm just giving information on possible alternatives - you really need expert advice if you want to get into this kind of thing. That's how I learned about it - from an expert. Or you can throw down a pad and carpet and live with it.

But these methods can work under the right circumstances and are finding some success in road repair, among other things. Here's a little history if you care to indulge.

http://www.iowaconcretepaving.org/AC...ons/sr903p.pdf