My concrete slab has a crack in it- now what?

Okay, Some of you may remember my problems with the concrete contractor not doing their job correctly... Well, I finally have seen tangible results of the crappy job: I noticed a hairline crack in the slab last night! It's about 4 feet long. My guess is it's less than 48 hours old. Now what? Can anyone offer advice on how to deal with it? At this point the drywall has been installed, door and floor will be next, so time is of the essence... Thanks for any and all help!

i think your going to have to live with it mate. or pull it up and do it again :cry: just pick a nice floor covering and cover it up. it is only hair line. got any pics. joey

No pics..but good idea. When I first looked at the crack, it looked like a squiggly pencil line- like I had inadvertently dragged a pencil along the floor...it's that thin. And hopefully it stays that way!

good luck joey.

It may not necessarily be a big deal. Concrete shrinks as it cures, and most of the time a hairline crack with be due to that - they're actually called "shrinkage cracks." That's basically why concrete slabs on grade contain reinforcing steel or mesh - to distribute the stress caused by shrinkage and keep the cracks small. For a slab on grade (sitting on the ground) there's no real structural reason to have reinforcing - strictly to control this minor cracking. How big is this slab? Is it a slab on grade?

Here's the slab: It's been 5 months so maybe I shouldn't worry? Like I said, I JUST noticed the crack- it must be fresh. Shrinkage crack I can take...

RichardM wrote:

It may not necessarily be a big deal. Concrete shrinks as it cures, and most of the time a hairline crack with be due to that - they're actually called "shrinkage cracks." That's basically why concrete slabs on grade contain reinforcing steel or mesh - to distribute the stress caused by shrinkage and keep the cracks small. For a slab on grade (sitting on the ground) there's no real structural reason to have reinforcing - strictly to control this minor cracking. How big is this slab? Is it a slab on grade?

Richard, All of the above is true - BUT - shrinkage cracks only occur during the shrinking stage of the curing process - and that is generally within the first day or 2. A crack that is an extreem hairline might not be noticable until dirt deposits build up in the crack itself. It is physically impossible to have a shrinkage crack turn up 5 months after a pour (that's 150 days +/-) and concrete reaches 100% strength in 54 days (+/-). If a crack has appeared this late in the game it would suggest to me movement in the concrete under loading. Thus a settlement crack as opposed to a shrinkage crack. BUT - depending on load- - that may not be a reallu huge problem - and if you really want it fixed and stucturally sound - you can always get a "structural epoxy crack repair" performed - it's costly - but the repair is stronger than the surrounding concrete that it's repairing. So they are not prone to failure. Rod

Here are some pics of the crack. There's a putty knife in one for scale. I don't know guys- this thing got a little longer and a hair wider since yesterday... The 3 layers of drywall are up on the walls now- so there's a good bit of weight on the slab now...

studio_drums wrote:

Here are some pics of the crack. There's a putty knife in one for scale. I don't know guys- this thing got a little longer and a hair wider since yesterday... The 3 layers of drywall are up on the walls now- so there's a good bit of weight on the slab now...

Drums, I explained that it was a settlement crack - it's going to continue until whatever settling takes place is completed. Rod

Thanks Rod.