Hi all,

Kind of a random question but I'm betting y'all can offer some good ideas. I'm having issues with my concrete garage floor cracking. I've been in the house for six years and for about the last three or four the garage floor has been steadily developing cracks. It's getting worse and worse as time goes on. My guess is there is ground movement happening but I have almost no knowledge in this area and don't see why this would be happening. Anyone have any ideas about what could be causing this? I'm not even sure who to call to have it looked at? Maybe a structural engineer...?

Any input/advice would be most appreciated!

Thanks,
Jimmy

Did whoever laid the concrete, leave room for expansion ? Doesn't sound like it to me.

If there are wells in the area withdrawing faster than the recharge rate, they can cause the ground to settle as well.

Cracking as in deep fault line looking cracks, or surface chipping and spalling?

if the former, you may have foundation problems.   Do you notice doors sticking, sheetrock cracks, etc?

If the latter, it may be road salt dripping off your vehicles breaking down the surface of the concrete.

It's the former, deep-looking cracks. I do have issues with drywall cracks and sticking doors, but the foundation walls in the basement look pretty good. My neighbour did have some foundation repair work done however.

I just had an engineer come out to my place yesterday.  I have cracks opening up in the garage floor, and up stairs, lots of cracks around iwndows and doors.

House has settled about 3-4 inches on average along one side.  Only upside is the house is a rasied ranch, so the settling has only affect one half of it.

Gonna cost about $15,000 to fix it with a bunch of steel piers sunk down to bedrock and some mudjacking.  

I'm now trying to decide if it's worth it and/or how hard the bank will laugh when I go to fill out loan papers for it.  

I'm sure will be seeing more and more of this as developors have to put neighborhoods on increasingly worse soils as all the good spots have already been taken.

Basement?  What's a basement?

We don't have those in south Texas, but we are more than familiar with foundation issues. Sounds like you are going to get familiar with them, too.

Good luck!

Who did you have out to look at your foundation?

mines garage doing it too.  and my driveway... has a cave of unknown size under it, i stood out there during a pouring down rainstorm, and watch untold number of gallons of water flow out of my rain gutter down a hole right next to the edge of my driveway.  and the water was not coming out from the bottom or up from anywhere else.

when i get my driveway replaced i cant wait to see what im dealing with there!  i hope its under the driveway only, and hasnt opened up under my garage!

If you're in the KC area, I can come look at it. I can tell you now, though, that the answer is going to lie in one of two, two-word phrases: "expansive soil" or "uncontrolled fill."

 

Yuppers.

Very common in my particular neighborhood. A lot of cheap housing built after WW2. Poor fill/compaction was used and my garage slab is only 2" thick in some areas.

Yup. There are ways to fix it, but as usual some of the suggestions in this post are simply wildly incorrect.

There are 2 types of concrete. The kind that is cracked, and the kind that is going to crack at some point.

Thx but I'm on the other side of the state near STL. Who should I look up in the yellow pages or internet to have this looked at... foundation contractor maybe?

Don't get too excited about that. Chances are it's a sub-base issue with settling fill under the slab.

Most people don't realize that skimping on the prep work before you pour is one of the worst things you can do to concrete. Use good material (processed gravel) and compact the heck out of it.

QFT

Whenever I'm asked about a guarantee, I always say my work is 100% guaranteed to crack at some point.

Concrete contractor. Look for someone skilled in mud jacking-helicoil work. many times, sunken slabs can be raised and saved, many times, they are too far gone.

Make sure you have a contractor that understands the fill beneath the slab but most modern builds are light years ahead of the way they used to do it. When people say "they don't build

them like they used to," I say thank God.

If you live in a municipality in which a permit must be pulled, you will be looking at pre-pour inspection. Pouring and screeding concrete is easy. It's the grading/compacting and from building

where the skill lies.

Love it.


Can you guys roll with 3000 psi in CT? 3000 psi is GTG in IL.

One and two family residential dwellings, yes. That's it. However I stopped using it almost ten years ago and just pour with 3,500psi on everything. It sets and finishes a little better.

I'm going to pour my driveway this year with 3500 I believe. Little cracking but tons of spalling. To me, spalling is the result of incompetence or trying to be a cheap skate. It pisses me off.

Dang it I was going to say that

Well, if you call a foundation contractor, you're going to end up with a bid to replace the concrete floor.

 

Around here, most ready-mix plants have "city" mixes that various municipalities specify for sidewalks, curbs and driveways. It's nominally a 3000 psi mix, but I can't recall the last time I saw a 7-day break under 3500 psi. 28-day breaks routinely go over 4200 psi. I've seen lean mix go over 3000 psi.





 

Do post-tension slabs prevent this issue?

What's a good way to look up a residential structural engineer? I don't know anyone personally and my search is returning a lot of non-residential engineers. Also would be nice to find someone with a good better biz bureau rating.

Meaningless for engineers.

 

Post-tensioning can help avoid shrinkage cracks, but generally don't help you in the event of settlement or other sub-surface issues.

 

Contact your local zoning/permitting office  talk to an inspector they should have a list.

I am a geotechnical Technologist and a manager for a Ready Mix supplier up here in northern Canada.

I took interest in reading this thread as I deal with this issue on an ongoing basis.  A couple things to mentions is all concrete cracks.  No if, ands, or buts about it.  Can get away from it.  How you handle it determines what it does.  As well, there is structural cracking and surficial cracking or surface issues.

What is being described with the op sounds like it might be a structural issue.  You need to distinguish between the two issues and go from there.  Structural issues should be fixed all the time in my opinion while surface issues can be addressed if time and money allow or if the desire is there to fix the issue.  Most structural issue are caused by poor prep work most of the time from what I have seen.  Occasionally contractors really mess something up structurally but most times it is poor compaction of engineered soils under a slab or not removing enough expansive clays or building on deleterious soils such as topsoil.

Most surface issues are caused by environmental issues such as too cold or too hot or windy during the pouring process.  As well, poor treatment of the concrete by over slumping thereby reducing the water/cement ratio or ordering the wrong design mix for the wrong purpose.  Most surface issues can be lived with however unsightly and a deal can be struck for monies returned for some portion of the project payment.

A couple things people need to know.  When choosing a contractor, especially on flatwork, ask to check references that are a couple years old.  Some times work defects do not show until year two or three.  Ask the contractor or readymix supplier what mix design they recommend for the climate you live in or the code required for your area.  It is different in all locations.  All outside flatwork that is going to be subjected to freeze thaw cycles needs air in it.  Generally air contents of at least 5% are required for all outside flatwork in a freeze thaw area.  All concrete needs to be told where to crack.    Cutting of concrete should happen as soon as the concrete will allow  you to cut it without unraveling.  Cracking naturally occurs as soon as the concrete starts to hydrate and set up so creating a weak spot in it will direct the cracking to the cut which will make it more attractive to the eye.

A couple more things.  Concrete is delicate in the plastic state.  Take care of it from excessive rain, heat and cold, and wind.  Don't let your contractor bless the top surface of the concrete.  Leave that for the pope!  Stronger concrete doesn't mean more durable.  Make sure you take care of your concrete every year by sealing it.

The company I work for subs a engineer but I have to do the core drilling in the locations they want. I usually diamond drill a 4" hole center of the crack.

They look weather it is cracking from rusting reinforcing steel and location of said steel in pour,  also check the make-up of sub soils and settlement of soils

I have taken classes with this engineer neil o. anderson

I do swimming pool repairs just to let you know

I am not excited about that, or being wrong about my guess. i really have no clue on problems with concrete floor's.  Skimping on preparations on anything will always bring shitty results.

Here in OH our contractors use a 4000 psi or a 4500 psi concrete for driveways.  Our 3000 psi and 3500 psi are reserved for footer and foundation walls only.

I used a 4500 psi for my driveway 6" thick and my father in law parks his tractor trailer on it.  Been 3 years and still no major issues besides normal wear and tear due to salt usage and plowing.