Concrete Slabjacking

Dear Tim;

The garage floor in my friend's garage is sunken in the middle, I estimate about 4" if not more from the height at the perimeter - very much like the diagram I saw on your web site (askthebuilder.com) which shows a depression in a concrete slab.

My question is, will slabjacking raise the center of the slab back to level (or very close to it) or is the slab, which is completely cured after some 14 years, crack or raise in it's present form like a soup bowl ?

Rob

Rob,
A professional slabjacker will tell it to you straight. I have seen them do what I thought was impossible.

I have a simmiler problem. I own a slab home and i cant find anyone that can help me with my problem. I live in dalton mass. and there are no comp. that i can find that do mudjacking, do you know where i could go to get a listing of all the comp. that are in this line of work in the northeast?? thanks for your time/

Brian,
Did you do a search using my site? Google knows you live up there by logging your IP address. They then serve up ads in the above column that are *geographically* matched! That is cool if you ask me. Right now I see ads above for Cincinnati, OH slabjackers.

I had a 1/4 section of my driveway replaced on 1/21 because the one the builder poured 5 years ago did not fade into the color of the rest of the driveway. It was drizzling during the pour and most of the week. The concrete guy put a plastic tarp over it w/bricks to hold it down over wooden slats. It has been a week and the slab look very light grey-not the color of the rest of the driveway. I am worried that it will not. He assures me it will "brown" up after about 5 weeks and fade it like the rest. He says he had the concrete plant to mix it so it does just that. He says it just needs sunlight and time? Is that accureate? He left some concrete in the expansion joints and some spillage onto the other parts of th edriveway as well. He says he will come back and clean it up in about a week (he is on a bigger job right now). Will that time frame cause a problem? I really hate the way it looks.
Thanks

Allegra,
The odds of that new pour matching your existing concrete is 100,000 to 1. That is not what you wanted to hear. The cement must be from the same batch and the sand must be from the same location for concrete and mortar to match.

Hmmmm. What is the average complete cure time for a slab? I am in Texas.

Allegra,
There is no standard answer..... There are simply too many variables and special mixes. I discuss this in many of my past Concrete columns. I suggest you read many of them.

We live in a Sacramento CA spanish two-story with a tile roof built 1929. A two story addition was added many years ago over an outdoor patio slab and joined with the existing structure. The bottom floor is a family room with pavers over the slab and the upper is a bath and 10X10 spare room. I have no idea what sort of foundation support was used, if any. Over the twenty-five plus years we have lived here the addition has settled perhaps 3/4 to an inch at the most remote corner as evidenced by ceiling,floor and exterior cracks and separation. Drainage and the removal of a large camphor tree may also have contributed to the problem. Does this sound like the kind of situation where slab jacking would be beneficial?

Bill,
It sure does to me. But I can tell you that you should get a structural engineer involved in specifying the fix.

I am looking at purchasing a new home, but there has been significant rainfall this year that has washed out dirt under the corners of the back patio and front walkway. Is there an effective way to repair these with common tools? What if i fill it in myself with some bracing and quick set concrete? Do you think that slabjacking is needed? Is there a good way to determine with the slab that ONLY the corners have this problem, or is there a way to see if there is slumping in the middle where i cannot see?

Thanks for your help on this. I dont want to buy a new home with these kind of problems, but my wife LOVES the home. Happy wife, Happy Life!! Right?

Kenny,
I can't answer without more data. Sorry! Install some crushed gravel and see if that helps.

There are homes in this area that have concrete slab foundations that weren't laid with Rebar. The soil is mostly clay and expands and contracts with the seasons. This has led to many people having slab issues, made worse by the lack of Rebar (sinking parts of the slab).

Would the material that is used to inject under the slab to un-sink it provide a good enough base to prevent the cracking from occurring under the concrete slab as caused by the soil expansion/contraction?

I currently live in Mobile Alabama and am on the prowl for a home. I found a home that is 27 squares and ridiculously under priced. After a brief inspection performed by me, noticed the upstairs master bedroom to be a bit unlevel. Now the house is a bit weird. the master has about a two foot overhang (almost like a window box) over most of the house and is supported by 12x12 pillars. (21 ft, 3 pillars with extending supports, almost like a psi sign) so i assumed the pillars were beginning to age. i then went to the bottom floor and noticed it too had a bit of a lean. i have yet to purchase the home, but with all the amenities this home has its almost a shame to let it off the list. Especially if something such as slabjacking could be performed for under 10k. i guess my question is, Would this be too much to jack (the 21 foot run probably 10 feet wide). It does seem to be continually angling and not seeping in at the middle though. And also, is slab jacking priced extremely high?

Thanks,
Anthony

My two car garage has a centerpost that was not underpinned with a load beam when the garage slab was poured. Now after 18 years I am getting a slight sag of 3/4" under that post due to the slab settling an equal amount. While it does not sound like much, it is enough to break the brick across the top of the doors at the top of the column. I was about to have it raised by mudjacking or pressure grouting but a structural engineer said if I did, I stood a good chance of filling the foundation drains around my house and creating a real nightmare. I have called several of the contractors I got quotes from and a couple said that is not an issue while the others say that it could be and that they take no responsibility should that happen. What is your take on all of this?

Thanks,
Vic

In regard to Allegra's concern and different colored concrete, you can get penetrating concrete stain that would make different areas of the driveway consistent. Rustoleum makes a semi-transparent stain, and there are many others on the market. Some folks do very elaborate decorative staining with stensils as well. I have a slab at the front entry that used to have a small higher step on top, and after removal, the area under the step was a different color. I plan to power-wash, and if needed, to etch the surface with acid and stain to achieve a consistent color.

I live in Edmonton, Alberta, Canada and I own a bi level with a some problems. Over the course of the last 6 - 7 months, the front yard has started sinking and bringing my house with it, to the point that I have some cracks in the foundation and the concrete floor in the basement has cracked and started to sink as well. I have had a couple of estimates done for putting in some piles and jacking the house back up, but I am curious to know if slabjacking is a possible solution?

Bill,
We have a cabin that was built on a slab in 1955. Over the years the sand beneath the slab has washed out in some areas causing cracks and a couple corners of the cabin to sink or "settle". My question is, will slabjacking cause the interior drywall to crack or shift when lifted?

I need a paving slab raised

(Long post but I'd like to accurately describe my need) My 2 1/2 car garage floor has sunken tremendously but all the damage is from before we moved into the house four years ago. When buying the house our home inspector said it was normal and not an issue unless it progresses. I'm finally ready to take care of this. The floor is two large slabs (roughly) 10x20 side by side for the cars (with crack width wise) and then two 8x10 at the back end of the garage for a work/storage area. One of the storage area slabs has sunk a lot in the the very back outside corner (near the house), so much so it's sticking up on the opposite corner where it meets the parking floor. The other is fine. One of the parking spaces is running lengthwise along the house's foundation which has a basement. It has sunk 3-5" where it has met the storage slab (the tilted one incidentally). We had a mudjacker quote $1600 to level all four slabs but then got a quote on concrete. The concrete guy mentioned not mudjacking because of the house foundation. I know he's trying to sell me his services but is there an issue with resetting these slabs next to a foundation? Thank you!

I've read your comments about slabjacking sinking concrete driveways. The section of our concrete driveway, abutting the garage, is sinking due to settling soil beneath. The foundation wall under the front of the garage is also the wall to the basement. Is there a danger that slabjacking, while raising the driveway, will also push in against the basement wall? If so, what other alternatives are available?

We have a concreat slab that we have a large porch over it. We noticed that one end of the slab is letting a little water spread back to the house (not a stream but a slow crawl) when it rains hard. The slab does not look uneven but it has to be somewhat to let this happen. Would you water proof the crack between the house and slab so absouletly no water can get between the house and under the slab?

Tim, I have a concrete staircase, poured in 3 sections, with 20 total steps, built into the hillside between my house and the road above. It's my main access to the house, but the hillside has eroded and the staircase has settled and is pitched downward a couple of inches. Dangerous and will only get worse.
After I install trench drains and some retaining walls to prevent further erosion I'd like to raise the cement stairs to level. Access to soil under stairs is easy from the sides, but I fear jacking up the concrete, which is very heavy, will cause cracking, etc. Is slabjacking the way to go here?

My house is built in a subdivision that has many cavarans and sink holes but was built on clay foundation. We have noticed that our concrete slab foundation has several large cracks in it and they have dropped down about 1 1/2 to 2 inches. We have been told that it is due to the clay losing moisture so we have been using a soaker hose to increase the water level in the clay and that has helped some. I was looking into slabjacking but I am concerned whether it is the right thing for us to do and the cost involved. Can you advise us? We live in Upper East Tennessee. Thank you.

What is the difference between slabjacking and mudjacking? A local slabjacker says his is better than mudjacking because his is a concrete mix, and the mudjacker is a slurry of soil which will further compact and erode.

True? Or "sales speak"?