Asked on Feb 27, 2012

Getting someone to diagnose Garage floor cracking.

by Ray
My garage floor has recently developed some significant cracks and I would like a professional to diagnose the problem and options to resolve it. I am wondering what profession is best to call? A concrete company, home inspector, or some type of engineer, or some other choice? Thanks for your help.
  18 answers
  • Ray, when you say "significant" cracking... can you post some pics please. A general rule of thumb is if 2 nickels, placed side by side, can fit into the crack. If so, its structural. If you have lippage, where one side of the crack is higher than the other, you may have a void under the floor or worse, we have seen where contractors have placed organic matter in the garage and subsequently laid concrete over it. Over time, as the matter decays, the floor drops... As a start, please post a couple of pics and if you can, place a ruler on the floor so we can see the extent of the cracking... thanks!
  • Ray Ray on Feb 27, 2012
    A couple of pics are attached. The cracks are long, but I don't see lippage and they are generally about the width of 1 nickel at most or less. The house was built in 1980, and I hope to put it on the market to sell it by year end. I'm interested in knowing it isn't something that a home inspector would say was serious, and is it better to leave them as they are, or are there inexpensive ways to improve the look? Thanks for your reply.
  • 3po3 3po3 on Feb 27, 2012
    If you are looking to sell soon, I would recommend getting an inspector through your house, including this, so you don't have any surprises. It's a tough real estate market, and the last thing you need is to have a buyer back out at the last minute because of a problem you could have easily fixed.
  • If the floor is still level on both sides of the crack, then what you have is shrinkage. Does the crack develop on a corner area? Very common spot as that is the weakest point on the floor. In any case these cracks appear to be worn on the edges which indicates that they have been there for a period of time. Cracks develop in cement for several reasons. One being the mix. In some cases more then one truck is used to pour the floor as one truck may not have enough cement in it. This results in each mix being a bit different with moisture content. As the floor begins to dry it does so at different rates from one pour the the other. This drying causes the cement to shrink pulling apart each pour until a crack develops. Another reason for crack is bowing of floor due to improper sub slab prep. meaning some areas were not properly compacted. This results in settlement of the slab in various points causing it to crack as seen in photo. The only thing I would first do is to take a large board such as a 2x4 and bump its end on the cement floor. If the floor sounds hollow, you may want to consider having someone pump a cement slurry into holes they drill into the floor to help support it. If it sound solid as you move around the floor bumping the board onto it, then you can simply forget about crack, or use cement crack filler and fill the cracks so no water gets into the floor area allowing freeze damage in colder winter months.
  • Ray Ray on Feb 28, 2012
    Thanks for the help. All of the reply posts were helpful. So far, all indications are that it isn't serious, except cosmetically. I like the idea of getting an inspector to look at the house before it goes on the market, and I may do it before I do a few other renovations, so that anything found can be addressed at that time. Thanks again.
  • Ray, it sounds as if it could be an old settling crack. One way to know for sure Ray is to super glue a piece of glass across the crack. If it is still settling it will break the glass and you'll know its growing worse. I'm curious as to if there are any cracks in the walls? And if you would like an inspection on the property Lilburn is typically out of our range of service but I think we could make an exception this once. I hope I was able to help.
  • recommend either a conc repr specialist, pro engineer OR any member of atlanta's chapter of intl conc repair institute,,, you don't mention the age of the garage floor - i have noticed very few floors have contraction sawcuts which, in most instances, prevents any random cracks. its possibe under-slab fill is settling & the floor's conc doesn't have the flexural strength to resist cracking. exacerbating the issue is parking on the floor - static (parked) weight is higher than dynamic (rolling) weight. if you want some free advice, there is a method of supporting the floor w/o slabjacking/mudjacking thru the use of polyurethane foam - we recommend prime resins in conyers (ask for terry ) - NO FINANCIAL INTEREST - just send me a note - lilburn's not far from marietta - good luck !
  • If you really need to fill voids under the slab, there is another vendor in the area who offers a similar polyurethane solution. They are in Conyers. Precision Lift Atlanta. Ask for terry harper. Just google or send me a note if you can't find their number... good luck!
  • woody's got a good idea but, in this area, cracks are most likely because the conc contractor placed 1 LARGE slab & did NOT provide contraction joints as is required to prevent random cracking. its also possible under-slab fill has settled either from poor original compaction, organic material, infiltrating water, heavier static loads ( weight ) than originally anticipated - UNFORTUNATELY precision lift is no longer operating ( financial pressures ) & terry is dis-associated. the parent company, PRIME RESINS, is financiall strong & i have dealt w/them over 30yrs. it now appears your best bet will be mudjackers - 1 of which seems actively posting on H/T - amazing may have a # for harper who MAY be operating on his own w/o precision lift OR prime resins resources. again, best wishes !
  • SlabJack Solutions SlabJack Solutions on Mar 05, 2012
    Give us a call anytime!!
  • Sandy Sandy on Aug 28, 2013
    Hi Ray. My garage floor has a serious crack going down the side. You can actually stick two nickels in between and one side is higher than the other. Could this be a structural problem that could cost lots of money?
  • @Sandy There are two basic types of cracks. One is shrinkage the other is settlement. The width of the crack is not as important as the displacement on each side. If the crack has settled down or up on one side more then the other, this can be a concern and then it may not be. When a crack is not even in height this can signal several things. One they did not properly compact the soils under the slab before they poured it. Two they did not provide enough gravel under the slab or poured the cement directly onto the soils below. Three they buried garbage under the slab during the construction phase. Such as wood cut offs tree parts etc. The ground is heaving or shrinking because of the soil type below the cement and your current moisture issues where you live. Heavy rain, or severe drought. Earth movement. Did your area have a earthquake? If the soils settled, which is the most common reason for displacement then the movement you currently have should stabilize and not get much worse. Poor quality back filling is often the cause. The contractors push loose soil around and cover it with gravel without compacting it. When the cement shrinks and pulls apart, normally from a corner the crack develops, if the soil has settled in the mean time one side of the slab drops causing that displacement if the soil has a lot of loam or clay this also can be an issue. As clay gets wet it expands greatly. If the ground was wet when the cement was poured and the soil dried out after, a void has developed and once the slab cracked because of incorrect prep and expansion joints or cold pours it will drop. If the soils were dry and then got wet, the clay would push the cement up. Take a solid wooden handle or even a 2x4 about six foot long. Bang in onto the cement floor. Move around and keep trying this. You should hear the sound change as you move around. This sound change is telling you that the soil below the cement is not supporting the slab in that area. Also telling you that you may have some more cracks or settlement in your future. In all actuality the cement slab is not structural in nature. Its not suppose to support anything its designed to freely float up and down. Control joints prevent any cracks from going any which way and proper prep of the ground before the pour prevents abnormal settlement. If you look around the edges where the cement abuts the walls, you will see the original level of the cement from when it was poured to today. If you want to fix this the best method is of course remove and do it again. However there is a method called mud jacking. This is where they drill holes into the slab and under pressure push a slurry of cement and soil under the slab and through hydrologic action they can push the slab back up to the original point and at the same time fill any voids that have been created over the years. There are dozens of reasons however why slabs sink. Without knowing anything about your home such as area where you live, types of soils, water levels, quality of construction, size of slab its impossible to determine exactly why this has occurred in the first place.
  • Sandy Sandy on Aug 28, 2013
    Thank you so much for taking the time to answer my question. The home was built in 1972 and located in Leonard, Michigan. I made an offer on this home without getting someone out to look at the garage. I close on the home this Friday. I feel a little bit better about closing. Thank you!
    • @Sandy Good luck with the home. One thing you can do is to check the crack. If its really worn on the edges that is a sign that this crack is older. Newer ones both on floors and basement walls tend to have sharp edges that have not yet worn down. Also look for lots of debris in the cracks. More so on walls, but that again is a sign that the crack is older. If your wondering if its still moving or not a trick is to glue a small microscope type glass across the opening. Using hot glue fasten it to both sides of the crack. If its still moving, the glass will soon crack, indicating that some movement is still taking place. If over a few months nothing changes, then you can be pretty much assured that it was a one time thing and most likely will not move much more if at all in the future.
  • CHalstead CHalstead on May 08, 2015
    I am looking at buying a house and went to view the same one 3 times. The sellers want to sell desperatly and I am in love with the house. One MAJOR concern: The garage floor is cracked down the outside wall all the way to the back, about half inch gap and the floor is separated from the walls on the opposite side where the basement is. Should I be concerned that this house has a foundation problem? The seller did not disclose this in the purchase agreement, and I have not made an offer yet. Should I???
  • StFrancis StFrancis on May 30, 2015
    I own a home in California that is only two years old and it has this same problem - extensive cracking in the garage floor, which makes me wonder what is going on throughout the foundation of the home, which is built on a slab. The builder says it is not a problem, but I would like to have someone check it while it is still under warranty. Who should I call?
  • Suzanne Suzanne on Jul 23, 2015
    I have heard on the radio that there are products that can be pumped under the concrete to "lift" it back into position - not sure if that would work on the entire side of a garage tho.
  • Grace Lopez Grace Lopez on Mar 23, 2023

    Every morning there is a small tennis ball size moist area on

    concrete Flòor board inside garage wall then it dries up by evening we had a company come out to see if we had mold or moisture on walls we do not it seems like this moisture seeps in from somewhere in floor structure who can we call to come out and check.

  • Mogie Mogie on Apr 03, 2023

    Cement floors crack it can be from settling of the home over time. Cracks of a greater width than 0.3 mm may present structural durability issues. If a crack on a concrete floor or slab widens sufficient to present a tripping hazard, it is considered serious and requiring repair.