Giant hump with crack on concrete basement floor

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Old 03-11-15, 04:14 PM
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Giant hump with crack on concrete basement floor

OK. First and foremost, I apologize for the long post.

I'm pretty sure this isn't going to be a DIY job, but I'm still posting here because I want to get a better understanding of the situation, and to get a good feel about how freaked out I should be right now (foundation things scare me).

I own a house that was built in 1968. There has been a huge hump in my basement floor since the day I bought it. I have always assumed that this was because slabs just weren't as nice back then.

Today I started the process of gutting the basement, and once it was all empty, I got curious about the hump. As of right now, all there is are cheap tiles that you stick on, so I thought I would remove one or two on top of the hump to see what it looked like. Turns out there is crack down the middle of the hump. I am not that surprised about the crack because cement obviously doesn't like to flex.

That being said, obviously, at some point something pushed the floor up. I read that water can do that, but there has never been any water in the basement since I've been here. I guess it's possible that the city had some water main breakage at some point over the years, but that would somehow surprise me.

What I do know, is that there used to be a giant blue pine tree on my front lawn, which has since been cut down. This is where my questions start:

-Is it possible that the root of a tree would go UNDER a house without damaging the actual wall of the foundation and push the floor up? If it helps anything, the wall which is adjacent to where the tree was is 100% clean, no cracks, no nothing.

-When I bought the house, the foundation was cracked at a window on a different wall, on the opposing side of the house - could this be related?

Is it possible that the house just kinda ''settled'' at some point over the years? It's not built on a swamp or anything, bug I guess it's possible that there was some ''soft spot'' that got compressed under the weight of the house?

-How freaked out should I be right now? Is the part where I drop the whole project and bring my keys to the bank?

-Anything else I should be made aware of?

Considering the size of the hump, it seems it would be easier to fix by cutting/chipping it out and pouring new concrete over it instead of using a self leveller. If it's just a matter of a few bags of cement and a little elbow grease, then I am good to go and should take care of this while my basement is empty.

If it's a 40K job, I am in trouble.

I'm really going to appreciate your responses on this, guy. I am trying to flip this house all by myself and (I'm sure you guys know this already), it's been an insane amount of stress for me. I'm never doing this by myself again.
 
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Old 03-11-15, 05:11 PM
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It could be lots of things.
Roots, high water table, shrink swell soils, someone did not bother to prep under slab, no vapor barrier, no insulation under the slab.
Only way to find out is cut it out with an abrasive saw and remove it.
 
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Old 03-11-15, 05:14 PM
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You are learning the hard way the when flipping a house, someone has to lose, the buyer or the flipper. If you cut enough corners you make a few bucks, but the buyers get a poor house. If you do everything right, the buyers get a great house, but you go broke. To end up with a quality house AND make money takes more than a newbie. But don't feel bad, there are thousands of others giving it a try, but I would never buy one.

Now, to your issue. How large of an area are we talking, half the basement or a 5' x 5' bump. If it is a smaller area, you rent a jackhammer and pick up a few 5 gallon buckets if you don't have any and in an afternoon you will have an empty space in the concrete waiting for new concrete. What you find down there will probably tell you how it became a hump, but it has to go in any case.

There are other pros who can explain the details about the best way to fill it back in and that will depend upon the size of the opening to be filled.

How large is the area, how high has it lifted, and how long has it been like that?

Bud
 
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Old 03-11-15, 05:15 PM
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I wouldn't worry about it. Someone buried a camel under there a long time ago. JK, I doubt that it's a 40G job. Roots wouldn't make a hump. It would be more of a linear break in the floor. There is only one way to find out what it is. Grab a sledge & a pick & chop away.
 
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Old 03-11-15, 05:48 PM
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Alright guys, thank you so much, your responses are helping alot.

The hump is about 3x7 I would say. At its highest point, it is 1.5", 2" at the very most.

Joecaption1 - I can guarantee right now that there is no insulation under there. I had to chip out a part of it already to add rough plumbing for a shower so I can confirm that.

As for how long it's been there, I would guess about 30 years maybe? It's hard to say... I know it's been there for as long as I've been here, which is a year and a half, and I know someone installed a floor over it before that and that someone tried to just fill the crack with cement before that (the more I tear things down around here the more head shaking I do when examining the previous owner's ''handywork''.

About flipping a house, thankfully I got it for very cheap, I am doing the vast majority of the work myself, and I have friends in various trades who can get me cheap materials, so it looks like I will probably still make some money in the end. Let's not start counting the hours I put in though 0_0 lol

Oh, I don't know if this helps, but I was also made aware by a neighbour that a swimming pool once exploded in my back yard. I'm assuming that's alot of water for the ground surrounding a house to absorb, which may have contributed to this.
 
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Old 03-11-15, 06:25 PM
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I'm not sure what the soils are like where you are, but participating here on the forum was the first time I had ever heard about "jacking up a slab home". It seem in TX and some other locations, they have so much clay that it expands and contracts with the seasons, cracking the slabs for which they tunnel underneath and jack them up. They must call them slab rats . Never heard anyone mention a basement slab, but thought I would mention it just in case your home is build on a lot of clay.

Bud
 
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Old 03-11-15, 06:34 PM
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Never heard anyone mention a basement slab,
That is because at least in my area there are no residential basements. Grew up on the Texas border north of Louisiana never saw houses with basements there either.
 
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Old 03-12-15, 07:33 AM
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Alright well that pretty much settles it then. I will wait until my vapor barrier is up (because it's easy to wipe the dust off of it) and I'll buy a few cases of beer and have the boys over to take out the worse of it and reassess from there.

Is it possible that I find nothing abnormal under there? If that's the case, do I just pour new concrete and call it a day?
 
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Old 03-12-15, 08:01 AM
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I get a kick out of the younger guys (Pulpo) recommending a sledge and a pick and this old guy says to head for the rental store and get a jack hammer. I'll wait for your follow up to see how you make out . A lot depends upon what they poured, how thick and the mix. Last one I had to break through was 8" of a really good mix, wow what a job.

IMO, I don't think you will find a root from a pine, the ones I have removed had a single tap root going straight down with a nest of surface roots near the surface. Roots are looking for water so under your basement slab is not where they would head.

If clay, you will want to remove more than just bringing it to the level you want. Take it down enough so you can add some gravel and compact it. Tie the new slay into the old with rebar or other, the concrete pros here can advise.

If you first cut a scribe line with a concrete blade around the perimeter, the final repair will look a lot better.

Bud
 
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Old 03-12-15, 08:05 AM
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Hopefully, that's all it needs. Wear safety glasses & a dust mask when you open the hump. Let us know the results.

Bud9051. I'm 63 but I guess that I could be younger compared to the rest of you. I wouldn't need a jack hammer, for one hump.
 
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Old 03-12-15, 08:40 AM
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hahaha!

I'm 29 and I was thinking of going the jackhammer option.
My uncle has a chop saw I can borrow, so what I think I am going to do is cut around the hump, have at it with a sledge, and if it's not moving, then go rent a jack hammer.

I'm actually very relieved by this thread because a lot of times when I post questions on here, I get very dramatic answers (which are very useful because I believe in not doing things the right way), but I am guessing in this case the answer my just be raw power. Break cement, dig a bit, add new cement.

Anyways, I won't be there until I am done insulating my walls, framing, and putting up my vapor barrier, so if you guys don't hear from me for a while, it's not because I forgot about you, it's simply because I am busy on the tasks leading up to this one.

Once again, I cannot express how much gratitude I have for this forum and the people on it. I'm ashamed to say that if it wasn't for you guys, I would have ended up building a pretty crappy house, because a lot of the advice I get from the old fellas around here (in real life I mean) is just plain wrong.

maybe if I stick around long enough I'll be able to start answering questions myself!

Thank you thank you thank you!

I will post here again in a few weeks.

Nic
 
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Old 03-16-15, 07:26 PM
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I just turned 70, and am definitely more feeble than I was 20 years ago--having been a diabetic on insulin for 53 years hasn't helped . However, I wouldn't hesitate to take a 10-lb. maul to a humped (and cracked) slab that's only 28 S.F. Could have it all out and in buckets in less than the time needed to bring a rental jack hammer back from the rental place.

And at 4" thick, that's less than 3/4 ton of concrete to remove and replace. If the helpers are worth their salt, it could probably be done for just one case of beer instead of two.
 
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Old 03-16-15, 08:17 PM
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Why would you demolish the entire floor for 1 hump?
 
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Old 03-16-15, 09:36 PM
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Read the fine print--I don't think the entire floor is just 28 S.F. Just a small, 4' x 7' portion of it.
 
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Old 03-16-15, 10:36 PM
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Just a bit of humor on concrete wrecking. I had a customer with an elevated concrete porch setting on brick walls about three feet high. She wanted the porch demolished and replaced with a wood deck. (Really wanted her to hire someone to do the demo.) I was explaining to her I'd need to rent a jack hammer. Telling her the reasons why I couldn't do it. It wasn't like I could just bust it up with a hammer. I had a claw hammer in my hand and to emphasize my point I hit the concrete with the claw hammer. The hammer left a six inch hole all the way through the slab*. Crap didn't really want the job and now I was commuted to it. <LOL>

*Slab less then 3", no reinforcement, and fill had washed out from under it.
 
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Old 03-22-15, 01:27 PM
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did someone mention BEER ? my guys work for $ & tacos
 
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