Hair line transverse crack in concrete garage floor in brand new home

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My home is 6 months old and when sweeping the garage this morning I noticed a transverse hair line crack in the concrete, that has appeared virtually over night. This is my last and final home to be built. (retired) I am concerned that I may have a problem in the future. How should this be repaired and what has caused this to happen? I live in coastal Georgia in a low lying, clay dominant area. We had a lot of rain this past year. My home was built under a contractor/home owner contract. Do I need to call my builder for repairs? Thanks in advance for any advice, help or guidance.
  24 answers
  • Jim B Jim B on Dec 17, 2013
    Hi Linda, I am a retired contractor, immediately call your General Contractor. They are responsible for home warranty of work for 1 year. Should you call your homeowners Insurance, or anyone else, I don't know. If contractor seems to be slow in responding you probably should call an attorney.
  • Linda Burns Linda Burns on Dec 17, 2013
    Thank you Jim. He has always responded quickly. Should the entire garage slab been taken up or just the crack repaired? I want to make sure it is done the right way.
  • Linda Burns Linda Burns on Dec 17, 2013
    Spoke with the builder. Being told that it is the expansion line and it is not unusual for concrete to do that. That it is normal and he has one in his garage also. He said that it would never get any bigger or change. That all concrete cracks. Is any of this correct or do I need to contact an attorney?
  • LandlightS LandlightS on Dec 17, 2013
    It would be helpful if you posted picture of the "crack". If it not a perfect straight line "crack" then I would say he is full of it. You may want to ask the city/county building inspector to stop by and take a look, or have a Concrete Contractor give you his opinion. Have a Merry Christmas in your new home.
  • Debbie Harris Debbie Harris on Dec 17, 2013
    If the crack appeared over night it is NOT an expansion joint. Expansion joints are built into the slab before construction. And sorry to say that you can't just take up your garage slab and do it over. The entire slab is poured before the house is built. It sounds like you might want to talk to either an architect or another contractor to get a written opinion. Sounds like your builder missed some steps to say the least. You might need to hire an attorney!
    • Spheramid Enterprises Spheramid Enterprises on Dec 18, 2013
      @Debbie Harris Garages are not on the same level as a home slab, by law they must be lower. Exp.joints only are used on very large slabs and most often on hiways , CONTROL joints are sawn in still "green" concrete or cut in with a joint tool while wet. I hate all this mis info here by psuedo professionals, this is not helping the education of homeowners, it is fueling legal action over what from this vantage point is a very minor issue. Questions to ask are, was a fiber used in the mix, what was the slump, was there reinforcing wire used? A plasticizer, was there a freeze after the pour? No one can call this shot with accuracy unless these points are hashed out. A photo would possibly help, but even then , without more info, calling a BI or Atty is pure "shoot first, then aim" sorry, but that is the truth.
  • Spheramid Enterprises Spheramid Enterprises on Dec 18, 2013
    Not uncommon at all. I'd not worry a bit about it. I would watch and see if it gets larger...but really, concrete shrinks, concrete cracks. If it did it in a place other than a provided joint, it is just that it chose to. Hairline, no big deal, liftage, or upheaval or sink..worry. WIDE open, worry. But hairline is nothing.
  • Jay Ladwig Jay Ladwig on Dec 18, 2013
    Three guarantees about concrete: It is heavy, it is hard, and it will crack eventually, sometimes sooner then later. Concrete shrinks as it cures, and can take months for a slab to cure to more then 80% of final cure strength. All builders hate to see a crack in concrete, but it happens, and if reinforcement was used in the slab, then you probably don't have an issue. Now, if the slab has a noticeable lift on the crack line, then that is another issue entirely. Experts should refer to the American Concrete Institute and verified sources for further information: http://www.bing.com/search?q=ACI+cracks+in+concrete&qs=n&form=QBRE&pq=aci+cracks+in+concrete&sc=8-8&sp=-1&sk=&cvid=5cff8d12d26c467fbc9cd56741ddb753
  • Bob Kovacs Bob Kovacs on Dec 18, 2013
    Two guarantees in life- the sun will rise in the East, and concrete will crack. You said it was a "hairline" crack, which is absolutely no cause for alarm. If the crack continues to get wider, or if there's a difference in elevation between the parts of the slab on either side of the crack, then it's something that may need to be addressed.
  • Robert Shaw Robert Shaw on Dec 18, 2013
    I'd be more shocked to not see some hairline cracking in nearly every slab, concrete cracks, it's what it does. As has been said if there is lifting of the slab then that is a different story.
  • Hairline cracks are just a reality of concrete and a natural occurrence. You could replace the slab 5 times and get cracks every time. Key word is "hairline". Just look at all the cracks in concrete bridges that literally have tons of rebar to hold them together.
    • See 1 previous
    • @ @Spheramid Enterprises It wasn't a hairline crack in the concrete issue Duane. There's hundreds of thousands of bridges in this country and you pick a disaster. There's also thousands of concrete slabs that get replaced with major cracks and upheaving. The point was that every single concrete bridge has hairline cracks, and they're heavily reinforced.
  • Thomas Bader Thomas Bader on Dec 18, 2013
    I've heard the 3 part concrete warranty to be a little different; 1) It will get hard 2) IT WILL CRACK 3) No one is going to steal it.
  • Terry's Flooring Terry's Flooring on Dec 18, 2013
    Don't let it bother you ..
  • Linda Burns Linda Burns on Dec 18, 2013
    Wow, I had no idea that this wouldn't be a cut/dry question and answer. I have attached a pic of the crack. I have also attached a pic of the footers the day before the pour. I was here every single day (lived up the road) and took pictures of the entire building process from land clearing to painting, every single day of the entire house. The slab is a step down from the home and the concrete poured was with fibers. It was poured April 24th in Southeast Georgia and it was plenty hot at that time. We have received a lot of rain since that time and the past few days have been cold. I think the combo is what has caused this crack. It is not unlevel and you have to really look for it. I just want to know, in Southeast Georgia weather, is this normal or is it a problem?
  • Linda Burns Linda Burns on Dec 18, 2013
    I am just as confused what to do as when I asked this question in the beginning.
  • Mark Parlee Mark Parlee on Dec 18, 2013
    Linda, You are looking for a cut and dried answer where none exists. It all depends. The photo you posted of the crack does not show anything to be concerned about. Watch it over time and if is grows to 3/16" wide or you get a level change from one side to the other of the crack then you call the builder for correction
  • Linda, This is large post, it should remove some of your confusion. The homeowner will question why his concrete is cracking and did they receive a shoddy job. When installed properly, concrete is one of the most durable and long lasting products you can use around your home. But it is important that concrete contractors follow well-established guidelines with respect to concrete placement. Durable, high strength, and crack resistant concrete does not happen by accident. Why do I have Concrete Cracks? Reason # 1 - Excess water in the mix Concrete does not require much water to achieve maximum strength. But a wide majority of concrete used in residential work has too much water added to the concrete on the job site. This water is added to make the concrete easier to install. This excess water also greatly reduces the strength of the concrete. Shrinkage is a main cause of cracking. As concrete hardens and dries it shrinks. This is due to the evaporation of excess mixing water. The wetter or soupier the concrete mix, the greater the shrinkage will be. Concrete slabs can shrink as much as 1/2 inch per 100 feet. This shrinkage causes forces in the concrete which literally pull the slab apart. Cracks are the end result of these forces. Why do I need to cure concrete? Reason # 2 Curing serves two main purposes. It retains moisture in the slab so that the concrete continues to gain strength It delays drying shrinkage until the concrete is strong enough to resist shrinkage cracking. Properly curing concrete improves strength, durability, water tightness, and wear resistance. Shrinkage cracks are common in most slabs we have installed flooring on, they are easy to fix, we use a cementitious patch to level and sand the surface. Your garage floor is not so easy. The crack repair treatment will show on the surface as a repair. The alternatives, Tear out and replace slab, live with the crack, (probably will not get any worse), install a conventional flooring product, apply a concrete stain and leave the crack as is or you could use a microtopping to create a new wear layer. A moving crack will have a surface height difference and are harder to repair and not reappear.
  • Jill Jill on Dec 19, 2013
    Call the contractor NOW. Most home build warranties only last for so long. If you let it go, you might have a problem down the line that you forgot to take care of. The contractor needs to inspect it and deal with it promptly. Do not let him brush it off. A foundation in a new home or garage should not crack. Having one do so is a big problem. And while some areas might eventually get small cracks, if this one should grow or spread into the home it's not good. Sometimes they will come in and have to stabilize the ground underneath by pumping cement into and under the foundation, a very expensive fix. As the home settles more, it could cause the home to be unstable. This problem could also be put on a title later down the line making a home unsellable and if your homeowners insurance finds out, it could also make your home uninsureable.
  • Bob Kovacs Bob Kovacs on Dec 20, 2013
    Geez, Jill- like to scare people much? It's a hairline crack with no vertical displacement- there's nothing to "brush off", and to say that "a foundation in a new home or garage should not crack" is a completely false statement". I didn't see a single control joint in the pics of the slab, so it's going to crack where it wants to (control joints are put in to "control" where the inevitable cracking will occur- hence the name). That crack is not something to be concerned with at this time, does not require pressure grouting, and will not be required to be listed on a title. Good lord....
  • Terry's Flooring Terry's Flooring on Dec 20, 2013
    I agree with Bob , on this one ...You know everything looks good on paper and life isn't always fair , but it's not something to get up tight about ..Jill , has your house falling in , in a few years ..Lol..Don't listen to her ..
  • Linda A Linda A on Dec 26, 2013
    You said you are retired? Listen, I have had a crack in the slab of my garage for over 10 years, my house hasn't fallen in and I highly doubt it will in MY LIFE TIME, how long are you planning on living?
  • Carolyn Vermillion Carolyn Vermillion on Jan 23, 2014
    5 months ago we paid a small fortune to correct another contractors mistakes and level the concrete floor in the garage- It is level now but has.small long cracks in it already. Happy its level at least and I wont find my husband rolling into the neighbors yard when he is on his creeper working on his car.
  • Don Gillette Don Gillette on May 20, 2015
    I just noticed a crack identical to yours today - in my 14 year old house. I immediately went outside and checked the bricks on the exterior for any crack and found none, so I'm not concerned. garage floors are normally poured INSIDE your foundation so they're not integral to the structure of the house. It's no big deal. If it bothers you (like mine bothers me) do what I'm going to do--paint the floor with a 1-part Epoxy Concrete paint from Home Depot. $40 a gallon, 2 gallons is more than enough for a standard 2-car garage, you'll have an easy-to-clean, easy-to-maintain, virtually stain-proof floor out there and it'll never bother you again.
  • Christian Mac Christian Mac on Jul 23, 2015
    Hi Linda, yes they are unsightly but unfortunately all large area concrete surfaces will crack at some point, its just part of the drying out process, most people don't notice them as there are floor coverings in place apart from the garage, so these cracks are likely to be in other parts of the house also. As long as there is no, or just minimal change in the surface height from one side of the crack to the other, you've nothing to worry about and often, if an attempt is made to repair it the end result only highlights the fact there was a crack there. i've been a registered Builder for more than 20 years and have pretty much seen it all before.
  • Charles Williamson Charles Williamson on Aug 14, 2018

    If it is less than 1 year old, it is still under the warenty.

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