cracks on new concrete slab ?

[fredinstl]

Hello all,

I would appreciate if you could share with me your thoughts, regarding a remodeling I just completed on my 1 story ranch, slab/no basement in St Louis MO: extending a 1 car garage into a 2 car garage.

They got rid of the old slab (on the one car garage) and then poured a new one for the 2 car garage 19' x 19'. After less than a month, it has now 4 cracks (cracks 1 to 3 intersects in middle):

1- from North wall going South of garage: 5' long, from 1/4" to 1/16" wide 2- from West wall going East: 11' long, from 1/8" to 1/16" wide 3- from East wall going West: 12' long, 1/8" to 1/16" wide 4- from Entrance (South) going North: 7' long, 1/32" wide

you can see pictures there:

My contractors talked to the concrete guy and here what he is proposing:

1/ fix the cracks with caulking etc... 2/ wait one year, if it gets worse: redo the whole slab, and if it doesn't get worse: fix the cracks as in 1/

Not sure what my expectations should be ? Should I ask to redo it now ? thanks. Fred

[Big Bob]

I live in st louis. apparently they did this in the all recent rain or they failed to do the base properly. can i ask which concrete company did this to you, for i am need a similar project done. btw: my opinion is to have them tear it up before the framing goes up and redo it. florissant mo

[Big Bob]

Also pics 8, 9, and 10 look deep as well as wide. don't mess with caulking, you'll never be happy

[SteveBell]

All concrete cracks.

A 1/4" crack is unacceptable, in my opinion. Your pictures 8, 9, and 10 show excessive cracking. The others are what I call "hairline", and I wouldn't worry about them. The small ones are expected.

Is there any elevation difference between the sides of the cracks? That would mean trouble.

What kind of reinforcing did he use? I would want post-tensioned cables, but those are rare in some parts of the country. Re-bar is the least thing that should be in there. I've seen people do garage floors with 4" wire mesh, but that's barely good enough for sidewalks, in my opinion.

How thick is the slab?

[cm]

Here in Arizona we have a state run agency called the "registrar of contractors" they have set guidelines on what is acceptable and what is not. Usually very cut and dry rules. Find out who your state agency is and get them involved. Your concrete will not get better, it will get worse and possibly effect the whole project.

cm

[trader4]

I would push hard for replacement now too. Unfortunately, this is one of those things where it's arguable what constitutes acceptable or what an acceptable remedy is. But for it to be this bad after a few weeks, clearly doesn't look good.

Like others have asked, I'd like to know how the base was prepared, how deep it was poured, reinforced, etc. Also, besides their proposed caulking, what exactly did they have to say about why it happened? Did they claim it was normal?

I'd also get the building inspector to look at it and see what he has to say. You do have a permit, right? Another thing that may help would be if you can make a case that to replace it now will be significantly less expensive than replacing it a year from now.

[ransley]

It hasnt even fully dried yet, it will get alot worse over 2-6 months.

[Joe]

Unfortunately, you probably signed a contract that did not specify the concrete mix/type. Locally , we specify '5 1/2 bag' mix or use the strength rating such as you see printed on the bags of Sakcrete and the like at the box stores. A good concrete supplier will also have a range of additives like fiber reinforcement that cost more and are definitely worth every penny. What you have now is pure concrete scrap, destined for the landfill. Sit down with your legal counsel and have him get you out of the mess. Then find a competent concrete contractor and get the quality written into the contract. Good luck.

Joe

[cshenk]

"fredinstl" wrote

These are too big. They messed up somewhere.

This is a normal hairline and not a big issue. YET. If it gets bigger, you have issues.

They shouldnt even be offering other than replacement. 1/4 to 1/8 inch cracks are not normal, expecially not just in the first month.

If you seem 'apologetic' for asking for decent service, they will take you for a ride and not offer yo what you know is your due (a properly poured and reinforced floor). It's nice to be 'nice' but this isnt a time for it.