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looking for ideas on leveling a partially sunk slab foundation

6K views 30 replies 17 participants last post by  seba83 
#1 ·
I have a slab that has dropped almost 2 inches on one side of the house. I'm looking for some options on the best way to bring that up to level. Thanks for any help in advance... This apparently has been a problem in this subdivision (built in the 90's)... Many houses in this area have foundations that have dropped..
 
#8 ·
im thinking dependent upon size of area..length xwidth vs amount of decline that a sand mix/mud job would be cheaper and faster..

that grout pumping seems to be used on smaller slabs and I would imagine you would crack the slab probably in multiple places trying to do that to a foundation slab.

it would probably have to be cut and done in sections which seems like a huge job.
 
#12 ·
I have a slab that has dropped almost 2 inches on one side of the house. I'm looking for some options on the best way to bring that up to level. Thanks for any help in advance... This apparently has been a problem in this subdivision (built in the 90's)... Many houses in this area have foundations that have dropped..
I’m confused by your original post:

Has the slab dropped or is this a foundation problem?



If you cannot lift the slab using suction cups, take the slab out, build it up with good clean fill or stone... temper the base and pour the new slab or a sunken section of the slab.
Grout pumping
I’m with Greg on this (I think he was joking about the suction cups) – tear it out and fix it. I’ve seen mud jacking go very bad and I’m not a fan.



Curious as to how you know the sinking has stopped?
Curious to know what makes you think he knows that the sinking has stopped?
 
#13 ·
Sorry for the confusion... I realized my post was a bit ambiguous... This is a 1400 sq' home built on clay dirt... The stem (exterior) wall on one side of the house has sunk about 2 inches... This has caused the slab to crack almost down the center of the house... Breaking out the slab and re-pouring is not a problem, but how about the stem wall... You can see the wall sheet rock pulling away from the ceiling...
 
#15 · (Edited)
Hi John, Yes its a concrete slap... The house has 18" deep contrete stem (exterior) walls with 3 1/2" slab... This foundation is poured on top of clay dirt, which I've come to learn has been a fairly big problem in this area if the dirt hadn't been prepped right... The stem wall (foundation) on one side of the house has sunk about 2"... As a result the slab has cracked almost down the center of the house and you can see the wall sheet rock pulling away from the ceiling in that area. There are other areas of the house that have sunk, but much less (about 1/2 to 1")... It appears the entire foundation (stem walls) has sunk to some degree..
 
#17 ·
In Florida they're using an expansion mix of urethane and concrete? They drill and pump sorta like spray foam and it lifts slab, not sure if they do this inside home, the demonstration was on a driveway.
How are they stabilizing these homes, if even possible. Here they drill and pin with rods.
 
#18 · (Edited)
Helical piers might be a candidate part of the solution.

But depending on where you are in California (maybe "ca" means Canada), talking about solutions might be jumping the gun. Around much of California any contractor doing the sort of work you need will be working with a geo/soils engineer. If your foundation is sinking due to local soil conditions under your house, you may have one set of solutions and expectations. If your foundation is moving because your entire subdivision is moving down-slope, you may have another set of solutions and expectations.

It can vary from street to street. If the problem is widespread in your subdivision, there's a good chance the engineers and local building department are tuned in.

I'm guessing (pardon me if I'm mistaken) that you're a homeowner, not a contractor. Lifting foundations and houses is work for a pro - someone with knowledge and experience, and insurance. Find yourself a good contractor and a good geo engineer.

- Bob
 
#20 ·
#21 ·
Hey Asevereid, Wow.. I just went to your link and read the numerous posts regarding the leveling issue you were dealing with (Of course the only help you got was what you already knew).. Sounds pretty much like what I have going on... In my situation, my sister bought a forclosure (only thing she could afford) and didn't think much of the drywall pulling from the ceiling and walls... She just figured it was typical home settleing.... I caught the issue when I went to inspect the house as I prepared for remodel... Now we are sitting on a slanted house trying to figure out the next step... Funny thing, Here in N. California, I can't even find anyone that does mudjacking or any other kind of foundation repair/lifting... By the way, did you ever check back to see what happened with that house?
 
#24 · (Edited)
.... Funny thing, Here in N. California, I can't even find anyone that does mudjacking or any other kind of foundation repair/lifting...
Really? Where is your sister's house located? Everyone does foundation repair out here, though I've never seen mudjacking or the like, because that's not necessarily going to solve a Ca-style ground movement problem - we have movement, not settling. Earthquakes and all. If you search for "seismic repair [your sister's home's location]" you'll find all the foundation repair companies.

Unless your sister's house is in the central valley or the delta, most contractors will call an engineer right away. I most likely wouldn't lift a house without an engineer's report and plans.
 
#22 ·
BobbyCA said:
Hey Asevereid, Wow.. I just went to your link and read the numerous posts regarding the leveling issue you were dealing with (Of course the only help you got was what you already knew).. Sounds pretty much like what I have going on... In my situation, my sister bought a forclosure (only thing she could afford) and didn't think much of the drywall pulling from the ceiling and walls... She just figured it was typical home settleing.... I caught the issue when I went to inspect the house as I prepared for remodel... Now we are sitting on a slanted house trying to figure out the next step... Funny thing, Here in N. California, I can't even find anyone that does mudjacking or any other kind of foundation repair/lifting... By the way, did you ever check back to see what happened with that house?
Call your local helical pier underpinning company . And be done with your problem .
 
#25 ·
Mudjacking may work, but some situations helical piers are the way to go. None of this is cheap to do right, especially not helical pier.

Didn't she have a home inspection done before purchasing? Cracked slabs and drywall pulling off the ceiling are usually tough to miss.
 
#27 · (Edited)
Hi John, The house is actually in Stockton, Ca - (Delta region)... As I've come to understand, this area has a nortious problem with homes sinking (that of course that didn't have properly prepared foundations)... I think its more of a ground sinking issue than shifting - at least in this situation... The soil in this area is all clay and I have friends in this area that have also experienced some form or another of noticable settling to their homes (cracked drywall or out of square doors and even some with broken tiles)... This house has all of these problems... Funny thing though, not a scratch or crack in the exterior stucco anywhere... I too knew what the true solution was before posting this issue..(calling in engineers, getting soil samples, legal action against the GC who built this home almost 30 years ago, etc...)... But, I guess I was kinda hoping (preying is more like it) that someone was going to come up and say, "I've seen this before and here's a good and inexpensive way to solve this problem"... I've even spoken to at least five GC's already and haven't gotten the same answer twice.. P.S... I went to your website gallery... Beautiful Work!!!!!
 
#28 ·
Hi John, The house is actually in Stockton, Ca - (Delta region)... ... I've even spoken to at least five GC's already and haven't gotten the same answer twice..
Stockton's definitely a settling area more than a quake area. Unfortunately, it was practically global HQ for low-quality building for a couple of decades. It was at the far edge of commutability to the Bay Area, and builders put up a lot of houses, without a lot of care. What have the different GCs suggested?
 
#31 · (Edited)
Hello Everyone and Happy New Year

Apologies for a long post, but this only way to explain the problem, which is similar to the one discussed here so I decided to ask for your opinions.

Friend of mine has a similar problem and I am trying to help him getting right people to get the job done.

His house is built on slab on grade, no basement or crawl space. I believe floating slab. On the perimeter of the house slab cracked, disconnected form the foundation and sagged 1-3 inches, depending on the area. Slopes are no longer than 5’, usually less than that. Structural engineer has seen it, couple of foundation guys too. They all concluded that foundation is fine, as of course it is much deeper than the slab and is not sagging.

All of the guys presented couple solutions each. Appropriate thing to do is to jack the slab out, compact grade, insulate it (current one is not insulated) and pour the new one. However, there is a haunch in the slab, and there are walls above it (and not only above it) which support construction so contractor would have to build columns and so. In addition, there is a beautiful bathroom remodeled couple years ago and it would be nice if it could stay (part of slab was redone underneath it). Friend realizes that all of this is doable, however to do it right it would cost relatively a lot of money.

All contractors also mentioned about band-aid solution. Just level the slab and see what happens. There are some indicators that sagging has stopped (it was leveled once and did not sag any more). Leveling concrete should be way cheaper than redoing everything. Friend of mine realizes that it would be a gamble, but is fine with it. A few neighbors did it and the problem did not come back.

So now we get to the root of the question – how to level that slab. Please look at the pictures. They show how much it sagged. This is a maximum, most of the slops are no longer than 4-5 feet (center of the slab is ok, just 2-5 feet around perimeter sagged). Another issue is that slab is covered with tiles cutback residue which most likely contains asbestos. The owner would like to do something like ardex feather finish or similar compound (gypcrete looks ok too, not sure about the cost...), but it says not to exceed ½” of application thickness. We need more in some places. Anyone has any idea how to tackle that problem and more importantly what materials to use in order to achieve described effect? Should some materials be layered? Also, as ceilings are low, we would like to minimize height addition to the existing slab, just to cover residue and level where is sagged. On the top of leveled slab friend would install vapor barrier, and floating engineered hardwood floor, clickable one so easy to remove if needed.

Any help is greatly appreciated.
 

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