Thread: Cracks in Townhouse Garage Slab

Hi all! We found a townhouse we really like and want to make an offer. Unfortunately we saw some worrisome cracks in the garage slab. The garage is under most of the house, so we're suspecting foundation issues. One of the cracks is pretty wide and long and goes across from one wall to the other (the thick line in the diagram below) and some are just hairline cracks, but the one at the entrance goes over the small step and outside. The pictures I took are only of the big crack. We checked also the townhouse for cracks in the drywall, but there are none to be seen. There's no way of telling if they were fixed and painted recently, but it could be. The house was built in 2008, so it is pretty new. We are planning on bringing in a structural inspector if we're putting an offer, but would appreciate your opinion on this before going all the trouble with the contract and then breaking the whole deal if there are structural problems. Pictures and diagrams are below. Thank you!

diagram.jpg
pic1.jpg
pic2.jpg
pic3.jpg

common cracks, seal and monitor. that is not FOUNDATION, that is 6" of concrete poured on the inside of the foundation walls and only has to support your cars. All slabs crack, some more than others due to poor installation practices. ask your broker to show you a few other units in the same complex and see what they look like. if they can't get you in, go take a walk on the weekend to meet your new neighbors, I think you will find they are more than willing to tell you about the condo and the complex. also I would say that meeting who you will be living next to is way more important than the thought you have been giving to those common cracks. good luck!!!

How old is the unit

Not that that gives much value to the crack. I feel garage floor cracks are an important issue but it may be the building did settle and stopped. That is an open crack and it should not be. The metal in the slab should have kept the crack from opening.

After saying that it truely could be not much to consider as far as not purchasing the property. What does matter is what does the rest of the unit look like. Are there drywall cracks, doors out of square, obvious dips or rises in the floor? Is it a brick exterior and are there cracks in it? I always advise my clients to at the very least have some foundation folks come in for a second opinion. Their software will show them exactly what is going on as far as total movement. They can and you inspector should have noted possible grading and drainage issues.

For as cheap as it is, have a second opinion. If it is nothing move on in. If it is something you can add an addendum for repair. If it needs repair and the repairs are done move on in. If it needs repairs and it is minimal and they do not want to fix it then way it out and see if it is something you can live with repairing.

Originally Posted by Ted Menelly

How old is the unit
The metal in the slab should have kept the crack from opening.

What metal, MESH?
Around here, no one puts re-bar in a garage slab.

The only thing mesh does is become a pain in the butt when it comes time to demo the slab.

That looks like a typical settlement crack that may or may not continue. Most garage floors settle because the contractors fail to properly compact the soil when back-filling the footings/foundation. The worse case is to remove the slab, re-fill and properly compact to 95% and re-pour the slab.

Non structural. Shrinkage cracks developed as concrete cured. Likely due to concrete drying to quickly after being poured.

Clean and caulk crack if you wish.

Thank you for your answers. To answer some of your questions: the unit was built in 2008, there are no other visible drywall cracks in the house and the doors seem pretty good, they do not stick. We already talked to people in the neighborhood and seen two other units, none have any cracks like these... I will definitely call a structural guy, if you have a recommendation in Northern Virginia it would be great! Thank you.

I agree with Raymond. It's rare that I get concerned over garage floor cracking. I'm pretty sure that one thing is a given - the structural engineer will appreciate taking your money.

Originally Posted by gchope2k6

Thank you for your answers. To answer some of your questions: the unit was built in 2008, there are no other visible drywall cracks in the house and the doors seem pretty good, they do not stick. We already talked to people in the neighborhood and seen two other units, none have any cracks like these... I will definitely call a structural guy, if you have a recommendation in Northern Virginia it would be great! Thank you.

Just hire a contractor that can hydraulically re-level the slab, and seal the crack. (They drill small holes and pump a cementitious slurry under the slab, causing it to re-level and close the crack). Should run a couple of hundred. Cracked garage floors are common.

I agree with most others - I see these several times a week and don't get too concerned. As others mention, the garage slab is not structural. It's really just a floor covering to park your car on so you're not on gravel. Go check out a new construction build and you'll notice the garage slab and driveway are pretty much the last concrete poured..... after the house is built and standing.

The only time I would worry is if there is differential settlement (one side more than 1/8" or so higher than the other). Most/many builders put cracks in the concrete on purpose at pre-determined places to manage where the cracks go so they are somewhat symmetrical. The one you're looking at may even be such a beast.

Originally Posted by gchope2k6

Hi all! We found a townhouse we really like and want to make an offer. Unfortunately we saw some worrisome cracks in the garage slab. The garage is under most of the house, so we're suspecting foundation issues. One of the cracks is pretty wide and long and goes across from one wall to the other (the thick line in the diagram below) and some are just hairline cracks, but the one at the entrance goes over the small step and outside. The pictures I took are only of the big crack. We checked also the townhouse for cracks in the drywall, but there are none to be seen. There's no way of telling if they were fixed and painted recently, but it could be. The house was built in 2008, so it is pretty new. We are planning on bringing in a structural inspector if we're putting an offer, but would appreciate your opinion on this before going all the trouble with the contract and then breaking the whole deal if there are structural problems. Pictures and diagrams are below. Thank you!

diagram.jpg
pic1.jpg
pic2.jpg
pic3.jpg

Lots of different opinions here. I am a forensic structural engineer and am asked frequently to comment on such cracks. Cracks in garages seem to be more common than cracks in the remainder of the foundation. The normal crack I see is from the overhead door to the back of the garage, about centered. The left-to-right crack described here is unusual.
The question of the type of foundation is still not answered. If this is a floating floor, then this is not a foundation problem. If the floor is monlithic with the grade beam/footing, then it can be a foundation problem. Addressing it as if it is a foundation: If this is a stand-alone foundation, this type of crack can occur due to shrinkage of concrete and the soils underneath reaching equilibrium in clay soils, where the soils will moisturize and swell. The soils bear against the grade beams and stretch the foundation, causing cracks. This type of crack normally breaks the foundation into two more square pieces, as in this case. Addressing it as if is is just flooring: No concern for the foundation, but this could become worse over time.
In all cases, rebar reinforcement should in found in this slab. In smaller slab sections, such as in properly laid out driveways with no slab dimension exceeding 10 feet, welded wire reinforcement is adequate. Garage slabs at 20+' x 20+' need rebar, the WWF will simply break as the concrete moves.
The structural engineer you may hire should check for reinforcement and the type of reinforcement by using a cheap metal detector, the type of reinforcement is determined by the interval of steel found.
I have found that filling concrete cracks always calls more attention to them, and if the crack moves the seal is compromised. Only seal if necessary, e.g. water ingress.
Concrete curing cracks do not extend the width of a foundation. The subject crack is not a curing crack. Curing cracks are hairline and wander.
Hydraulically or underpinning repair to the slab will not close the crack, it is meant to level flatwork.
Overall, the sense of the responders is that cracks in concrete are no big deal, do not necessarily show foundation movement nor indicators of larger problems. That is what I find also.

Originally Posted by gchope2k6

Hi all! We found a townhouse we really like and want to make an offer. Unfortunately we saw some worrisome cracks in the garage slab. The garage is under most of the house, so we're suspecting foundation issues. One of the cracks is pretty wide and long and goes across from one wall to the other (the thick line in the diagram below) and some are just hairline cracks, but the one at the entrance goes over the small step and outside. The pictures I took are only of the big crack. We checked also the townhouse for cracks in the drywall, but there are none to be seen. There's no way of telling if they were fixed and painted recently, but it could be. The house was built in 2008, so it is pretty new. We are planning on bringing in a structural inspector if we're putting an offer, but would appreciate your opinion on this before going all the trouble with the contract and then breaking the whole deal if there are structural problems. Pictures and diagrams are below. Thank you!

diagram.jpg
pic1.jpg
pic2.jpg
pic3.jpg

Since the answers you are receiving are all over the map I thought I would add my 2 cents. I am a HI and a SE. Part of the reason you get many different answers is that inspectors are from all over the country and construction practices and other conditions vary widely. The Forensic Engineer from Texas say there should be rebar in the slab. He probably deals with shrink/swell clays. I'm from PA and we do not have that condition. You probably do not either. You would never find rebar in a tract home slab in PA (at least in my area).

It is hard to say from the photo, but it does not look like that slab has settled any significant amount. If this is a one car garage then the slab is about twice as long as it is wide and a shrinkage crack would be likely at that location.

Someone said the crack should be tight. They often are not. If there is welded wire mesh in the slab and it is in the top 1/3 of the thickness then the crack would likely be pretty small. Every slab I have opened up has had the mesh at the bottom. I hear this from many other engineers. Common practice is to pour the concrete over the mesh and then try to pull it up with a hook (while standing on it).

Someone mentioned slab jacking-pumping concrete under the slab for a couple hundred dollars. In some areas this is common practice and maybe in Indiana you could get it done for a couple hundred dollars. Its a couple thousand dollars in my area. This is sometimes done when there are voids below the slab or if the slab settled. When this happens pumping concrete onto improperly compacted fill usually causes more settlement. Engineers do not generally consider this a permanent fix. Settlement of a slab is usually pretty apparent, especially if you look at the edges of the slab-you can see marks on the walls where the slab had been. Jumping on the slab or sounding it with a hammer, steel bar, chain. piece of wood can detect voids. You will hear a hollow sound instead of a dull thud. In my area most garage slabs are poured adjacent to basements and the fill adjacent to the basement wall is usually not well compacted. I see lots of settlement and voids.

Garage slabs are usually not structural (referring to my area), but I have seen a few cased where columns or walls are bearing on slabs that do not have footings below. I wrote an article for the Journal of Light Construction outlining I such case. Those repairs can get quite expensive.

Bottom line in you case is if the slab has not moved much and there are not voids below it, it is probably not a big deal, but inspected a slab from two photos and a diagram is something I would not do.

Another point. when an inspector says to seal and monitor a crack what does that mean. Are you saying its ok, but may not be ok later? If you are pretty sure it is a shrinkage crack, then the seal and monitor comment is probably fine. If you have any doubt as to whether the crack is structural then the seal and monitor comment is poor advice to a client.

I inspect 50 year old homes in this area, have in Mass and in Florida. A large amount of those homes never cracked at all. Some do a little and then there are those that have open 1/8 inch crack and then there are those that the floor has heaved all over the place.

If, and I say If the ground was properly taken care of below that concrete and the proper concrete mix was used for that area/soil/climate etc there should be absolutely no cracks in it. Especially if the perimeter of the home and property were all prepared properly.

If I see cracks in the driveway and the home was a new build I direct my buyers to politely attack heavily until the builder repairs them such as rip the original driveway up and doing it all from the soil up all over again. It will not get better over time. If there are cracks all through it, in a year the driveway is going to be heavily cracked all over the place.

In a garage such as this it may not be a big deal but it is an existing home and homes do move over time to a point. What point is acceptable? You are the buyer and that question needs to be answered by you.