Cracking Concrete Floor

Sounds like the soil was not compacted before the house was built.

You need to have is looked over by a foundation pro, ever increasing problems show that the problem is biger than just what is showing. Are you built on top of a Landfill or other soft surface? A sink hole (anyplace) or artesion water problem at the bottom of a hill can do similar damage.

I wish to thank you for your reply to my problem. We will be taking him to court.

Landslide,

It seems clear that you need repair work and in my experience epoxy paint will not return your garage floor to anything acceptable, ie cover up 1/4" cracks.

I would suggest that the first thing you do is find the root cause. Is the water you mentioned coming out of cracks in the concrete? Do the cracks stop at the foundation wall? Are you familiar with the nature of the soil your home is constructed on? Is there any other foundation damage?

Yes we have problems with the whole foundation wall. We will be taking him to court. Thank You

Poor compaction coupled with poor sub-base drainage seem to be the problems also you have do not appear to have a Damp Poof Membrane under the concrete as well which wouldn't be a major problem in a garage if it wasn't for the drainage issue.

Two main options are:

Either replace the floor with new, ensuring your ground is solidly compacted and free draining the best way to do this is to excavate 12" is usually enough so that you get down to undisturbed ground and refill with aggregate and then the last 4" with sand each layer should be vibratory plate compacted. If you don't' remove the existing soil you need to ensure that is well compacted, jumping jack style compactor is usually best for this. Then at least lay down a vapor barrier of 10 mil (millions of an inch plastic) and lay Welded Wire Fabric 6Ga Min (This is to reduce the effect of tensile loads on the concrete and to stop cracks pulling apart) this should be in the top 2/3 of up form the base of the concrete. I do not think there is any need for control joints unless you have any floor drains or centre columns that are likely to cause unsightly cracking during shrinkage when curing. You will need a footing drain of gravel and perforated pipe to take away ground water and make sure your roof drains and gutter flow run away from the building.

Concrete should also be allowed to cure properly to gain full strength a 3-7 day wet cure (covering plastic or burlap/hesian and keeping wet) this also helps to prevent shrinkage cracks. Shrinkage cracks occur because the concrete needs to release stress caused by contraction due to moisture loss when curing items such as columns and drains will cause stress concentrations so control joints are cut around the (you will nomaly see a rotated square formed around such item and each corner a cut will run to the edge of the concrete, this can be tooled when wet or cut with saw prefrable before cracking starst from the base. These type of cracks cannot be stopped fully in a large in situ pouring, so we use control joints to make the cracks appear where we want them to. This type of cracking is increased in hot weather but is not the root cause of your problem.

The second option is to use a Hilti Crack Injection epoxy http://www.us.hilti.com/holus/modules/prcat/prca_navigation.jsp?OID=-12192 to try to prevent the cracking from opening any more (on a non structural floor you could actually hit the floor with a hammer at the end of the cracks to ensure they have propagated fully and have thus stopped cracking).The floor could then be painted or screeded with an epoxy floor screed or leveling compound (such as quicklevel). Epoxy paint would do, but you should inject the cracks with the proper crack injection epoxy and you may need to feather in the subsided sections to the main pieces. Again you need the same drainage arrangement.

Remember to fix the drainage issues in either case.

There are a few things that also need to be considered:

Has the floor stopped subsiding or will continue to.

What is the rest of the drainage like around the building (are existing drains blocked or does it flood during time of high rains)? Do you have gutters with down pipes that take the water away from the buildings footings? Are the gutters blocked? (These are all problems I have seen causing damp around building footings and floors).

Is the water seepage a winter occurrence?

Was the concrete floor reinforced with welded wire fabric/rebar's or is there nothing in the concrete at all? The reinforcing helps to prevent cracks from pulling apart.

What are your footings like for the walls of the garage (is there subsidence)? This is just to tell if it is a problem with the floors alone. Or is the garage a thickened edged slab constructions (footings incorparated into the slab/floor)?

Note if you just fix one item alone the other problems of water seepage may still occur or the cracked concrete sections may become loose and move under loading, it is best to do it properly. It would also help to know what the rest of your house construction is like; is that also concrete floors? And I take it from your post you have no problems there.

I want to thank you for your input. We do need to replace th floor and do drainage work. We will see what is under the concrete.

If you dig up , you will find a soaked slurry. Water sipped in and liquified the soil. This liquified mass allowed the cenre point of the 3-car garage slab to go down maximum at centre.I am sure -you will find the floor sunk maximum at middle.Reason is above.

Now if you sue the Concreting Contractor:

The Excavation guy will tell the court that his excavation was according to code. The contractor will tell you that he did it acording to the plans drawn up by the architect, so its not his problem as long as the plans were according to code. The architect will tell you that YOU did not get a soil sample done and so its not HIS fault. So, good luck with that.( Courtesy#28) . Is it worth going to Court?

So as everybody said--Water is the culprit.

In#7 I gave you 2 directions to go. May I repeat SAME?

42 POSTS -ONLY FOR A SUNK (hence Cracked)GARAGE FLOOR!!!

Who did this job? Sue him for bad workmanship. Any concrete contractor knows the proper steps to do and this guy obviously did not follow them.

http://www.bobvila.com/BVTV/HomeAgain/Video-0816-03-2.html

http://www.construction-resource.com/forum/archive/index.php/f-10.html

I agree with aurizon. You should not have to deal with this on a new floor, and epoxy coating is most definitely not an appropriate fix. Sue for bad workmanship, and then have the floor redone by a competent contractor.

Thank you for your input.

In the UK, building projects are subject to review at intervals by local authorities, who inspect the design and construction as work proceeds. In a recent building project on weak soils, a structural engineering firm was consulted to determine the strength of the soil at depths to -16m (well into the local water table, as the site is adjacent to a river), and the foundations for the building. They then designed a reinforced concrete "raft" foundation to allow for the soil strength and the intended weight of the building on top. The design also had to cope with the construction date and method of the original building attached to it (brick under-walls on modest brick foundations with a timber frame on top, dating from 1843) and the revised method of the extended building (2006). The structural engineering firm's report, calculations and correspondence are available to the owner of the building and the local authority, and the local authority's inspection team have reviewed the project at intervals during construction, providing key milestones for the inspection process at which points the builder could then proceed to the next step of construction. This procedure establishes a high level of confidence in the buidling structure and allows a high level of redress in the unlikely event of a structural fault becoming evident over time. As an aside it also establishes a high level of confidence in the structure upon the property being sold to another prospective owner, and the documentation needs to be kept secure until that time and transferred with the buildings upon change of ownership.

Check the contractor's warranty situation in respect of the concrete that has failed and try to establish a way forwards without using a court as a first step. Most reputable contractors will want to put things right to avoid weakening their reputation.

If that fails, and before making application through the courts for redress and a contribution towards the costs of repair, check that the appropriate design and inspection documentation is to hand in this case. To proceed without it may be unwise.

Also, check the building is insured for subsidence repair and that the contents are insured against the building collapsing upon them.

Thank you for your input about my problem. It seems that the contractor poured the slab not on any compacted soil. We live in Cape Cod Massachusetts and it was put on only a sand base.

I thank you for your input.

once the cracks go all the way through and the concrete between the cracks became different in hight, that means the soul under the concrete floor was not packed well. the only perfict solution is to open the cracks wider then insert steel mesh in the cracks and fill the gaps wiht high cement concrete

#1 said it all. You have now 2 directions to go:

1. Fill fresh Concrete and make level---maybe will not crack visibly for a couple of years!Cars will need parking elsewhere for 2 nights.
2. Dig up the floor, Compact very tight, pour Reinforced Concrete which will sink as 1 slab after many years.

Read what "Guest" 02/12/07 has to say, he is spot on !!!!.

Do the job properly in the first place & you don't have these problems. Is the slab laid in conjunction with the wall foundations or footings or a slab laid in between ? if the wall foundations are sinking you have got more problems that just a slab cracking !, under-pinning etc. could cost a mint.

Who laid the slab ? the concretors should provide a warranty on their work if it was sub-contracted, hit them up to properly replace it, I assume the slab was screeded flat when laid, run a string line across it to see if is rising up or sinking down, trapped water under a slab can create a hydraulic pressure enough to lift an in-ground concrete swimming pool up out of the ground !

I'd rip it out & start again, patch it up & it'll never be right, have a serious look at where the water is comming from & fix that 100% first.

Brien.

We don'nt know how it was prepared. We were not there. We will have to replace the floor. By doing this, we will know how bad the situation is. Thank you for your comments.

bE CAREFUL OF THE INFO PROVIDED BY THE "guest" 10 MIL VISQUEEN (PLASTIC) IS NOT 10 MILLIONTHS OF AN INCH,............ IT IS 10 THOUSANDTHS OF AN INCH

Thank you for the correction. I would have hated for Landslide to have got hung up at the first hurdle.

You have a bad drainage detail outside the garage that is feeding water to the base material beneath the floor slab. You will have to find this poor drainage detail, and correct it so that NO WATER can reach the perimeter of your foundation system. The water is reaching the base fill and swelling it upward, or 'heaving' the floor slab. This is causing the classic 'heaving dome' in the middle of the floor and the fractures emanating from it. After you have corrected the drainage issue that MUST BE THERE, you will have to remove and replace the base fill AND the floor slab. I am a licensed, professional structural engineer and do this for a living. I am telling you the truth about your problem.

I'm sure we have a drainage problem. This garage is a separate building. This was poured on one of the hottest days of the year. The contractor said he did everything posible to keep the concrete from cracking. We do not beleive him. Thank you

This is clearly the result of improper preparation. Poor compacting of the soil, perhaps not enough stone, or maybe even not the correct rebar or correct rebar spacing, maybe not even any rebar. Knowing this is a floor of a garage the concrete should have been reinforced with rebar spaced according to the design specifications. The rebar helps to reinforce the concrete when loaded. Ask the builder if the concrete was rebar reinforced, and if he doesn't know, the floor can be X-rayed to see if there is rebar. You may have some recourse with the builder or the subcontractor if the floor was not properly constructed.

Good Luck

Hi , I dont know from which part of world U R ? But in my contry i . e In India it happens regularly , as we have big difference in temperature during various seasons as well during summer between day and night , due to this concrete floors get cracked ,

But in your case I think the problem is related to native soil , as you have mentioned about water , there might be a problem of water loging due to high level of under ground water ,and dueto pressure of under ground water the concrete might get cracked ,as during my studies I have seen a loaded under ground fuel tank at a textile mill in Nadiad town in state of gujarat ,India ,had came out of ground during monsoon due to under ground water pressure.

or the soil of your garrage might be a Black cotton soil , Black cotton soil has kaoline clay in it which has a negatively charged particles , when this negatively charged particles come in contact with water it reacts and due to this the clay particles swells as aresult pressure generates in it ,due to the pressure it has a tendency to rip the structure abou it , In India in south gujarat , I have seen the entire house or a masonary structure having cracked built on Black cotton soil ,

So please get tested your home soil first , Regarding applying apoxy or any synthetic material might help U temporarily .

As a contractor I assume that the crack radiating out from the middle made the middle higher than the foundation edges, the perimeter foundation may be sinking! This is bad - the concrete foundation is usually done by a different subcontractor than the floor. In addition if you are in a freeze area the perimeter foundation may not be deep enough and you are getting heaving which raises the perimeter foundation. Also if the water is continuous, you may want to test it for chlorine to see if there is a city water leak under your home or if it is groundwater.

The foundation was poured under the frost line. We don't have any town water near the building. Thank you for your comments.

Typically, settlement in the foundation will leave circumferential cracks as the edges of the slab are pulled downwards. This appears to be an issue with the subgrade, since it functions as a pavement section, a number of problems could be at issue, moisture in the subgrade, weak subgrade materials (insufficient R-value), expansive soils or compaction (overcompaction or undercompaction). as the crack open and more water penetrates, this process will accelerate. You will likely need to remove the floorslab, and pour a new garage floor slab, plan on overexcavating the subgrade, recompacting and moisture conditioning, and placing 6 to 12 inches of a nonexpansive high strength material like class 2 agg base under the concrete section somewhere.

Landslide,

First, what is provided is not professional advice and you should consult with a professional engineer or appropriate professional as dictated by state/local authorities.

With that stated.

Might you attempt to resolve the symptom, you should then look at the cause. This should save a substantial sum of money as the floor should not have to be removed. The question at hand appears to be the water that you mentioned that is coming up into the garage and the "...cracks radiating from the middle..." this would indicate that you have a hydrostatic issue (bulging) and not a settlement issue. The cracks that you describe are typical of said. Removal of the floor and compaction would do nothing to solve the responsible issue, resulting effect is you would have the same problem just with a problem with a new floor and compacted sub-base! Have you or your neighbor(s) altered the surrounding topography (stormwater flow)? Is the garage below grade? We have a client with a 16 car garage below grade. Anyway. Your solution might be to open an area just enough to investigate the sub base/soil/water and install a sump in same, then run for several months to dry out, then run your car or equivalent load over the garage to resettle (as much as possible), then float with epoxy. Voila, solution with less expense!! Again, consult with your local professional.

Hydrostatic (water) is the base problem to start the investigation then move from there. You might hire a lawyer and then find out that his lawyer hires someone like us, just kidding, and finds out that you or your neighbor changed the site conditions that caused the problem. Then you are stuck with the lawyer's bill for yourself and his and as mentioned a new floor and compacted sub-base with same old problems. UGHH!

Just some thoughts. Good Luck.

Disclaimer: this is not provided in any professional capacity and is only provided as a courtesy.

Consult a professional in your state/locality.

Best regards,

Channing

Thank you for your information about the water and cracking problem. It is something that I would not have thought of. But I do not think this is the problem. Thank you again.

These problems should not happen with replacement slab work, unless an unrelated, unusual water event occured, unrelated to slab work, such as high ground water around the foundation.

It sounds as though you may have (3) problems:

1) Water is getting under the slab, possibly the foundation also. Advise from a waterproofing contractor/consultant is needed.

2) The ground is wet and unstable, you need to determine why, advise from a civil engineer on the stability of the soils & drainage is needed.

3) The concrete has failed because the ground is unstable. The concrete work should be investigated by a structural engineer. He would provide advise (is the building safe?), then design repair or replacement methods.

Research well to find good people to advise you. I previously was a general contractor now working for a large A/E firm as a design consultant. From experience, it is rare to find anyone who personally is an expert in all of the above. A good engineer/ contractor will not have a problem admitting that. Contractors would not be expert at all of the above, although some exceptions may exist.

You need experts in each field if it is going to court. After you get the repair figured out, & can assign fault, attempt to allow the party at fault to pay for repairs before you go to court, it will save all parties money.

Thank you for your input/

Perhaps someone already mentioned EXPANSIVE SOILS. That sounds like your problem. These soils have high clay content and will expand substantially when wet. The expansion pressure will easily shatter concrete slabs, and can lift and crack foundations. Local codes always address this issue where such soils are common. Perhaps your garage was done without a soils report, or perhaps expansive fill was imported by mistake. Nonexpansive fill can be placed and compacted when the slab is reconstructed. The foundations are a more difficult problem. You'll need an engineer on that.

I assume you are not in a cold climate?

A and E firms, Soils reports, Local Authorities and X-rays. You had better turn the garage into a dwelling. These are all well meaning, but what is the cost of the garage compared to these and how does it effect the value of your property (is it a worth while investment to go over the top), I am sure you have already considered that. Either you replace or patch the floor and install sufficient drainage. The first reply's were most sensible ones, for a basic run of the mill on grade garage these are not needed, unless you are building a more complicated below grade one with upper levels etc. If you have no problems with the water table elsewhere in that location a few well placed inspection holes will save you a lot of time and give you a good insight into the ground conditions. As usual take everything with a pinch of salt, some good sensible options have been laid out before you.

There usually isn't the soil testing done by a structural engineer in residential projects that is done typically with commercial construction to see if a structural slab is needed. A civil engineer had to do a perc test. First I would also grab a copy of the results to see what kind of water table you have. If there was an architect, this would be his responsibility to ensure proper slab reinforcement. If there was not an architect, it soly rests with the general contractor. You might find your answer just by looking out your back window at what kind of vegetation is growing. Are there wetlands nearby? Take it all into consideration to form an educated conclution by getting all the facts.

Thank you.

No problem. I see you are down the Cape. I would give a call to Ralph Noblin at Noblin and Assoc. in Bridgewater Ma. and use him as an expert witness if or when the time comes. This is exactly their line of work, and Ralph is very knowlegable on the cause and solution.

I want to thank you for that information. We will try to contact him about this problem. One thing that I have noticed about contractors on Cape Cod is that they seem to not care about some of the work that they do. I'm sure that there are many that do very good work, but we seem to be finding all of the bad apples. Thank you again.

Thanks landslide. This is the same guy we use whenever we have any concrete issues. We have been doing business with Ralph for about 10 years.

We tried to contact him, and got no response back.

We live in a cold climate. Thank you.

Here in Gauteng, South Africa we have a dolomite problem and the symptoms described seems to be the same.

What happens is that the calcium compound (rock and soil) firstly dissolves in the water and drains away, leaving a less dense soil which then compacts under gravity. the effect is called a doline. The eventual effect of the dissolving rock and soil is that a sinkhole may form. 80m deep sinkholes was recorded and whole houses disappeared.

The big problem is that cavities (in rock or soil) might exist.

The tricks with dolomite is:

To drain surface and ground water as well as possible.

The soil should be strengthened with layers of soil and concrete. compaction alone will not help.

If there are any caves or dolomite in the vicinity i would advise you to

1 evacuate the house fast or at least stay away from the effected part.

2 Get an engineer to do a investigation.

drill test holes and note underground formations.

Drop a 5 ton weight repeatedly on the surface to collapse cavities.

3 do not try to patch the surface.

4 steel reinforcing will rust away in the dolomite water.

Good luck.

Thank you.

The key to this is the part where you say that water is coming up through. This is a drainage problem. Expanding soil will not suddenly cause water to up through it! It is water pressure in behind that is doing that. Get rid of the water, and the slab should settle right back down where it was put in the first place. Put drainage tiles all around the outside as per code. If that fixes the problem, then epoxy might tide you over for a decade or so.

If you want a new floor...well....

Are the walls attached to the top of the slab, or are there walls with footings? If it is walls with footings, it won't be that expensive to jackhammer out the floor and put in a new floor over the brand new 5/8 crush and drainage tile. If it is "slab on grade", you have the same problem, but it is a lot harder to fix! (lifting the building, that sort of thing!) (I have done both in my time. Its not as bad as it sounds.) Normally a slab is 4 to 6 inches thick in the centre, with a rim 16 to 18 inches thick. Less rim is weak, and more rim causes "frost heave" problems.

My workshop is built on a slab. Because of a slope in the soil, the back was much more than 16 inches...closer to 3 feet actually. (frost around here is 4 feet). Slabs must be well above the frost line so that they can shift and heave evenly. Mine developed some cracking due to being too deep into the ground on the back. I dug it out, and it is all good now. Cracks all closed up. I could epoxy if I thought the cracks were too ugly. (But my problem was frost, not drainage.)

It is counter intuitive, but it is what the code demanded. Guess they know what they are doing!

I have seen a couple of cases of bad workmanship end up in court. The results were mixed. It is hard to prove...expensive to file, and often not really cost effective. If you are definetly on the side of the angels, it might be worth the trouble. But the concrete guy will tell you he delivered good concrete,and its not HIS problem. The Excavation guy will tell the court that his excavation was according to code. The contractor will tell you that he did it acording to the plans drawn up by the architect, so its not his problem as long as the plans were according to code. The architect will tell you that YOU did not get a soil sample done and so its not HIS fault. So, good luck with that! You will have to find a written statement somewhere that the contractor was responsible for the drainage, and you must pay for an engineer's report that the drainage was faulty. Assuming of course that it WAS faulty. I do feel oblliged to mention that my daddy used to tell the story of his neighbours's cow. The two neighbours disputed the ownership of the cow and the lawyer milked it.

Hope this helps. A trench all aound the outside to drain off any water is probably cheaper than a lawyer. And you have to dig the darned trench anyhow! This might just fix the problem like it did with me.

Oh, and the advise to get in the professional who is familiar with the soils in your area...best advise on this thread!

The first logical thing to check is the concrete prep, formula, pour, finish and cure...by the contractor. More outlandish explanations already mentioned are possible...but why haven't they affected the foundation/house/lawn/etc etc.?

I note that concrete pour would have been extensive for a 3-bay garage. Apart from improper drainage (gravel) and vapor block beneath the pour--and improper rebar setting--might also be found that there were no or insufficient expansion joints (at the footings) and control joints in the pour for so large a floor.

But, the good part--no matter what--is that it's a new, soon to be removed and repoured floor...at expense of the original installer!!--who's almost certainly at fault. So use the engineering services not to fix the problem, but to test(ify) what was done wrong. Use a lawyer to fix the problem.

You can find out how much water transference is coming through the concrete surface by doing a Hydrostatic Vapor test. If the vapor is greater than 3 lbs you will need to get that water drainage problem fixed.

When you have the floor replaced and the soil has been properly compacted (after drainage issues are addressed), make sure that the concrete contractor provides enough control cuts and expansion joints to allow the pads to move independantly.

Epoxy floors can help with surface water that may want to go down into the concrete but it wont solve the crack problems. It will hide the cracks but it wont stop them. The concrete MUST cure for a full 28 days before you can put an epoxy on it. To do that before would simply be wasting your money. If your Hydrostatic vapor is between 3-5 lbs, you may not want an epoxy floor. Epoxy sealants typically seal the surface completely. This layer traps the vapor between the surface of the concrete and the epoxy, causing a giant bubble. After the water soaks back into the concrete, you will be left with a bubble full of mineral deposits.

Just registered. I install epoxy floors. I mentioned the hydrostatic vapor because some people think paint is paint and it will ultimately kill a floor if not considered.

Hope things work out with the new floor.

If there is photos,it's better.

but in my opinion,if the floor is built on the soil,the engineer's proposal dosen't work.

The solution to your floor problem would be "Uretek" it is used worldwide.We use deep injection non invasive procedures to repair this type of problem ,also roads, bridges and subsiding foundations etc. Yes older technology would probably call for a new floor and maybe even underpinning. we however pump an expanding polymer in which fills all the voids and displaces the water, and the nice part is you can use your garage immediately and it is probably 50% of the cost of conventional methods.