Part of our house foundation needs to be replaced under just one area of the house. The original foundation was rock and mortar which had started to lean. Someone in the past has tried to bermed up the old foundation with concrete poured right next to it, but this is now failing. We are looking for information on how to replace the foundation ourselves. Is it something that we should attempt on our own? Has anyone out there had experience with this?

-- Laurie (Lporter@nutracorp.com), August 22, 2001

Answers

This is a complicated project. First you have to jack up and support the part of the houseover the damaged foundation. Use a hyd. bottle jack and make sure it is rated for at least 20ton. Jack it just enough to take the pressure off that part of the foundation. Remove the damaged foundation and take it back into solid material. Make sure you have a good footer, if it's bad, dig down below frost lind and put in a new one. When it has set up for at least one week, buuild up the new foundation . Keep the pressure of the building off it until it has cured, then let the house back onto the foundation. Good Luck!

-- Paul (treewizard@buffalo.com), August 22, 2001.

OUCH,,,, well,,, first,, see if there is a "rat wall" some type of concrete base they put the first foundation on. If so,, good. KNock out some holes,, put in supports,, metal posts, beams,, whatever,, then lay your block foundation as you normally would. If no, "rat wall",,, then you got me,, could try to berm it up again,, with a large dirt pack one,, thats my best guess.

-- stan (sopal@net-port.com), August 22, 2001.

How big is the part you're going to replace?

-- Yup (Yup@nospam.com), August 22, 2001.

Pray ! We did it to our house and would not want to again .We hired someone .

-- Patty {NY State} (fodfarms@slic.com), August 22, 2001.

Paul gave good advice but I'd just add a couple of things. First off depending on how big your house is I found the 12 ton hydrolic bottle jacks work great on smaller lifts and are a lot cheaper especially if your lifting with multiple jacks under a large section of sill. The 20 tonners are nice though and if in doubt it doesn't hurt if there bigger. Second, I'd get some jack stands or other support such as small sections of 6x6 cut to fit along side the jack so you don't leave them under pressure. I ruined a couple of my jacks by leaving them under pressure for prolonged period. Maybe they were just cheap jacks but this method also precludes the jack slipping from a small leak in the hydrolic seal which is a real possibility. It's a big job and I wouldn't tackle it unless your real handy and have a pretty good understanding of the dynamics involved or know someone that does. It's not that big of a deal but I found it pretty spooky when you start lifting up the side of your house and there are some serious forces involved. On the other hand you might save a bucket of money doing it yourself because the material cost for the repair aren't usually that great and you're often paying a premium for labor, expertise, and liability insurences when you hire a professional. I'd shop it around for estimates, do a lot of brain picking, and then decide if you have the confidence to do-it-yourself or if it's just better to pay the difference and go to the movies while someone does it for you.

-- Carter (chucky@usit.net), August 22, 2001.

One thing I would add, it is VERY VERY important that you jack it up SLOWLY. Stoping for a few hours between jackings. You can do a LOT of damage to the house structure if you jack it up too quickly. The house needs time to recoop between jackings and it lets you see how each one is going (ceiling cracks, etc.) before progressing. As I recall, we jacked ours up over a period of 2 or 3 days.

Another thing is to take the advice above and use jack stands. There is a LOT of weight and if one of your jacks fails, severe structural damage can occur to say nothing of all your new work that is not set yet.

We did ours ourselves at our old house, but would never do it again -- we were young and foolish and thought we could do anything! This is a scary do-it-yourself project and if you mess up you have seriously effected your biggest investment. If you can at all afford to have it done for you, it is well worth the cost!

-- Karen (db0421@yahoo.com), August 23, 2001.

Roger that Karen,

If you have to move the house more than 1/2" I think it's definitely a must to limit each move to about a half inch and wait an extended period of time to allow for things to realign. Also if your lifting a large section you want of lift in tandem. That is to say don't jack up one end of the house 3" then go to the other end. Lift it all 1/2", then lift it all another half inch etc. I've jacked up and stabilized several foundations and am in the process of squaring up a 109 yr old building right now that had some rotten sills and has settled as much as 4 inches in some places. I plan on taking a long time and allow it to stabilize for months in between moves. In one part I have a 12 foot long, 15 inch thick oak beam that was under a cantilever stress when the sill rotted out. It has 4 inches of deflection in it that probably took 50 years to settle into that position. I'm not going to be in hurry to push it back straight. I'm figuring a year or more to complete the project because of some of the extreme deflection involved. This might be way conservative but I'm not in a hurry to screw up the building. I'm even wondering if I should moisten the beam or something. If anyone out there has some hard data on plastic and elastic deformation in large wood support members please pitch in. I've learned a few things from experience but on this one I'm going into uncharted territory. One problem I had when seeking "professional" help was that I couldn't find anyone that knew more about it than me. A lot of people that do this stuff are just handymen with hydrolic jacks. As a professional engineer, (mechanical), I even had the luxury of picking my structural collegues brains but while I got some info, most were at a loss for definative answers on what exactly to do to guarantee success. I'm still looking for someone who has extensive experience in extreme applications like I have, so if your out there please respond. So times you get situation that are hard to apply theory and need old fashion trial and error experience. My questions would be:What are the max recommended movements and how long should you let it stabilize before the next movement? Is the wood even elastic after 100 yrs plus. Can I even get that beam straight or should I just get use to sloping floors. The foundation is good and the sills were stabilize 20 years ago but the people doing the repair didn't jack the columns up and left the deflections so the a lot of the floors slope this way and that and I'd really like to square it up. While some might just consider it character in an old building, it drives me nuts.

Sorry for getting so technical, it's an engineer thing.

-- Carter (chucky@usit.net), August 23, 2001.