Brand New Concrete Cracking

11/16/2018 at 10:32:16 AM

Anything at or over a ten by ten linear square foot at 4 inches thick should have control cuts in it. Also it sounds like they didnt have enough fill in the base and its settling and there may not be any wire in there either. If I were to have a mess like this I would remove and replace without a doubt. Find out what strength of concrete mix they used and find out what the code is in your area to help with getting this issue resolved.

11/16/2018 at 10:36:50 AM

The reason for cracking is due to a poor sub base. The Contractor either did not install a sub base or it was poorly compacted which now the material under your concrete is sinking causing the concrete to have no support. Extra saw cuts wont resolve this problem. Once the water gets into the joints and under the slab if it freezes the cracks will heave. In Canada we use minimum 32mpa concrete where there's exposure to frost and thaw. I personally would have the slab replaced and make sure they use a plate tamper for compaction.

11/16/2018 at 1:22:59 PM

Most concrete floors will crack, however if done properly (excavated, weeping tile added, proper fill added and compacted) you should never see water coming in, and cracks should be at a minimum, and perhaps only develop years later. Frost will heave any slab if it was just poured on the ground, you are not in Florida! If you see water coming in that doesn't sound like any drainage was done, and may occur even without cracks since concrete is pourous. If it has not cured yet and is exposed to freezing temperatures, we all know what water does when it freezes - expands.

Good luck!

11/16/2018 at 3:58:25 PM

Absolutely, definatly request for your concrete to be re-done. Should be under guarantee. If contractor is loyal and legal is not reason why they won't do it.

11/16/2018 at 5:02:39 PM

Concrete no matter the age will crack. Just depending if its minor "spider cracking" or structural cracking" due to improper base or compacting of the gravel or moving etc. There shouldn't be water coming up through the cracks though, that sounds like there is a lot of moisture below it or they poured over top of a lot of water... or could be natural hydro static pressure which wouldn't be the end all be all. I always put poly, stone and rigid foam before basement and sometimes depending for garage pours. The cracks look to be minor spider cracks but after 3 weeks is concerning along with the water as well. Bring in another concrete expert and do some more research and ask your concrete contractor what his thoughts are and go from there. All the best.

SteveBuilt Inc.

11/17/2018 at 12:09:02 AM

Any large slab will always have a degree of cracking - it's the nature of concrete. Your photos do not look atypical. I previously worked for New Home Warranty and foundd that homeowners love to complain about any concrete cracking.

Nevertheless there are various things that can be done to minimize cracking, including proper prep, adding a 10 mil re-bar grid and ensuring the proper slump. The Code is weak on requirements for site prep unless the slab is carrying structural loads and is over 24 x 24' in the case of a detached garage.

Other respondents haven't talked about the common practice of cement finishers requesting water be added upon arrival to improve workability and lessen work. Concrete testing may show the strength has been compromised in this way (it's happened to me many times and often I will have testers on site to eliminate this problem). Poly is not required under a garage slab.

You haven't said if the garage is attached or detached or how large it is. Often with both attached and detached garages there will be minimal prep done and the prep in your case may very well have met common industry standards.

It's unlikely you will have any success in requesting the floor to be replaced unless it can be found that there is a Code violation which is unlikely.

You could visit the office of your local building inspector, ask for comment and perhaps ask to be shown the small section of the Code on the subject.