repairing sagged foundation

[ER_Hopeful]

anyone has experience/knowledge on foundation repair?

A couple weeks ago I discovered the back corner of my house has sagged about 1.5 to 2 inches over a distance of about 20 ft (measured using a string level). The problem footing also has 2 cracks plus one loose piece near back corner(it moves if I push on it). Please attached pics.

The house was built in 1949, on slab(no crawlspace), about 1100 sq ft.

I had 4 contractors here to inspect and give estimates. Their recommendations varied quite a bit. Here's their suggestions.

contractor 1. - do underpinning by digging 4 holes along the current footing, go about 2 ft deep, put rebar, pour in new concrete and bolt it to the old footing.

contractor 2 - no underpinning neccessary, my problem is far away from that. just patch up the cracks, remove the loose piece and pour in new concrete, then jack up the house. $4500.

contractor 3 - major surgery. temporarily suspense the wall, cut off affected interior flooring and slab, meaning about 14 ft long and 4 ft wide (into the house) and pour in new footing and slab.

contractor 4 - similar to #2 but with padding before pour in new concrete.

So what's a good solution to my problem? Although we plan to live in this house for a very long time, but we don't want to waste money by overkilling it either. Is contractor #2 a proper fix ? would like to get some opinions on the different suggestions. Thanks in advance.
added: I don't mind the uneven floor. My main goal is to stop the sagging and repair the footing.

btw, there's a couple possible causes of the sagging.
#1 the walkway is sloped, so it ponds when it rains.
#2 the main outlet leak (where the cast iron connects to the clay under the footing) which has been fixed a few months ago. I changed it to abs.
#3 overwatering from neighbor. I'll probably put in a french drain soon.

 

[zinger1457]

I'm certainly not an expert but it does seem they all failed to address what caused the problem, the fact that something is causing a section of the existing footing to sink which is causing it to crack. Sounds like you have some ideas on the cause (water from somewhere) but until that is adequately addressed and fixed what would stop any of the offered solutions from having the same problem in the future. Where's Tommy Silva when you need him!!!

 

[Sandhog]

I'm a practicing structural engineer NY and I like to suggest you get a structural engineer for consultation in your area (LA?) to save yourself grief.

Settlement of foundation footing can be cause by many different variables. Is it soil bearing insufficient? Has soil been eroded due to rain? Did footing failed cause the settlement? Is footing base property designed?

From the picture, looks like it's a frame house on the concrete footing. And looking at the open area of slab on grade, water might have travel to undermined the footing but couldn't tell from the picture. If I was living in LA, I would be able give you recommendations and shoot the breeze over cold beer. Best wishes.

 

[Dimsumkid]

I would suggest talking to a structural engineer (or more).

I had a 1 story addition that was 20' X 16' that was built on a 30" footing only, a crawl space with dirt and no slab. The sole plate was water rotted and had to be repaired/replaced. So I used 2 heavy duty bottle jacks and a 4"x4"X8" to remove and replace it myself. Had no issues with it sagging or sloping. A few years later, we thought about building a 2nd floor over this, all it had was a screened in porch and 1/2 a shed roof on it. We called in a structural engineer who told us the footing only went 30" deep and needed to be 48" (to the frost line) and recommended 7 piles of underpinnings which would prevent any sinking of the foundation and then I could build on it. At 2-3k per pile = 21k, we decided to just rebuild what we had. I really appreciated the opinion from the engineer and his quote/estimate was at no cost too.

I'm sure there's multiple ways to remedy your problem, which it seems you're getting from different contractors now. I'd feel better getting an engineer to look at it first. I know the underpinning process involves firing rods under hydraulic pressure to support the foundation. This seems to me to be the strongest remedy.

 

[devans0]

Ditto on the structural engineer. I had one outlying brick pier foundation that was breaking apart. The structural engineer drew plans that a DIY could do including how to install rebar to best effect and brand and type of concrete to get and sill plate to spread the load. The code inspectors were very happy and signed off on everything with no hassles. That alone was worth it. Total cost, $260. ($60 for cement and rebar)

 

[ER_Hopeful]

I called several structural engineers from the yellow pages, couple of them never got back to me, one wanted $300 for inspection then another $500 for report/suggestions . one engineer came by (he drew the blueprint for my mom's room addition) and looked at the problem briefly free of charge. His conclusion was pretty much the same (the ponding of rain and/or my main leak caused the sagging)

just wondering will a more serious(paid for) inspection be able to conclude what caused the sagging? or will the engineer basically tell me what/how to fix it? I think it's kind of hard for an engineer to tell what cause the sagging unless he breaks up the concrete, dig up the soil and say there, water coming from your neighbor and that's what cause the soil to erode.

 

[Dimsumkid]

Ask the engineer who wants to be paid what he plans on doing on the inspection. I actually dug up the area next to my footing to see how deep it went into the ground. That way I knew and when the engineer looked at it, he didn't need to guess either, no surprises for anyone. Not sure if you can/want to do this, but it eliminates any "best guesstimates" on how to fix it.

 

[calmloki]

There are companies that pump concrete under sagging foundations or slabs - never priced them out or used them, but it seems like a neat idea - worth a little calling around?

 

[travelover]

There are companies that pump concrete under sagging foundations or slabs - never priced them out or used them, but it seems like a neat idea - worth a little calling around?

I had this done on my driveway about 12 years ago - worked great. Can't comment on whether it is the solution for the OP.

 

[Bestwifeever]

We had to have a 25-y/o room addition on a "traditional" foundation propped up with several hydraulic piers; there were village permits required and a civil engineer (paid for separately by us but recommended by the foundation company) had to inspect and sign off on the foundation company's plan before the permits could be issued.

The concrete "mud-jacking" system sounds like it could work for the OP but the cause of the sinking would need to be addressed.

 

[Buckeye]

Victoria's Secret is having a big sale ..........oh, nevermind.

 

[Sandhog]

I called several structural engineers from the yellow pages, couple of them never got back to me, one wanted $300 for inspection then another $500 for report/suggestions . one engineer came by (he drew the blueprint for my mom's room addition) and looked at the problem briefly free of charge. His conclusion was pretty much the same (the ponding of rain and/or my main leak caused the sagging)

just wondering will a more serious(paid for) inspection be able to conclude what caused the sagging? or will the engineer basically tell me what/how to fix it? I think it's kind of hard for an engineer to tell what cause the sagging unless he breaks up the concrete, dig up the soil and say there, water coming from your neighbor and that's what cause the soil to erode.

You can do a test pit without destructive test or breaking concrete footing and that's all a structural engineer need to make an assessment. Make sure an engineer is licensed in your State. In California, structural engineer is SE and professional engineer is PE. SE is also a PE but PE is not SE. SE is an endorsement to PE is required for 3 story or more. For your case, PE is sufficient if PE is structural field. I do believe up to 3 story residential, PE can do since it has minimal earthquake and ASCE 7 design criteria. You can verify SE or PE in California through this website. http://www2.dca.ca.gov/pls/wllpub/wllquery$.startup

Try to speak with someone who used a structural engineer or go to on going construction site and ask who's the structural engineer. Most structural engineer are not listed in yellow pages. Good ones like myself gets clients through word of mouth. Also, most SE don't deal with home owners unless it's referred by one of the developer or contractor since most home owner's pain in the butt for fees less than $700.00 (too much time spent on explaining every steps) I start doing it because favor from a large client who does various development project. It started with making assessment for his mother's building then all lots of home owners start calling me to resolve there foundation and floor sagging problems. I do it since it's I can get paid for day's work instead of waiting on damn architects to finally make up their mind about masonry or steel or concrete framing, where to locate hot tub....

No SE will design a remediation sketch without finding a root cause. If he/she did, his/her professional liability insurance will be dropped on a lawsuit due to collateral damages.

 

[Sandhog]

There are companies that pump concrete under sagging foundations or slabs - never priced them out or used them, but it seems like a neat idea - worth a little calling around?

You can also use helical pile to jack up foundations. But it all depends on the root cause of the problem and soil bearing condition to have permanent solution that's cost effective. Contractors whether it's concrete pump jacking or pile jacking most always getting an engineer to design and sign-off since they don't want the liability of a failure.

I still recall my freshmen orientation where dean from college of engineering said, "anyone can design a bridge but only engineers can design sustainable bridge cost effectively."