sagging floor/reinforcement in basement

Old 11-23-03, 12:48 PM
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Question sagging floor/reinforcement in basement

Hi, I'm new here and I hope I'm posting this question in the right place.

This is my problem/questions:

My house was built in the 40's. It's all rough cut and the main "beam" running the length of the house is actually 2 trees that join in the middle where there's a support pole (it has a full basement). There's also one in the middle (on each side) of where these meet in the center of the house (so there's 3 total). The one that's in the center of the house is pretty flimsy looking and I'm kind of surprised that it's held as long as it has .

So today I put in one of those metal support poles that adjust right next to the one in the center. You can tell by looking at the floor up here on the main level that it's sagging near the middle of the house. How much should I jack at a time to try to level it back out? Do you think it would be best to try to even the load between the old pole and the new one and leave the old one in? Cause if I jack it up too much and take the load off the old pole it will fall out of there.

My main concern is trying to get the floor somewhat straightened back out and reinforcing these load bearing poles. I bought 5 of them and I plan on putting one right next to each of the old poles, and maybe putting a beam with a couple at each end under my kitchen floor.

Any help or advice at all will be greatly appreciated.
Old 11-23-03, 03:26 PM
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Nathan - hopefully anyone that responds to your post will tell you the same thing.... get professional help ! You are dealing with a critical structural element of the house. By manipulating the main carry beam, you could do more harm than good. Look for a good builder or framer to give you advice or to do the work.
Old 11-24-03, 06:04 AM
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Thank you for the reply. Unfortunately I can't afford to hire someone to look at it and I don't know any builders. I think I'm just gonna put these new ones in next to the old ones for now just for reinforcement. I'm not gonna try to jack it up at all.

Thanks again.
Old 11-24-03, 08:54 PM
bungalow jeff
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I'm goning to have to echo RichD on this. Hire a structural engineer with timber frame experience. The cost is less than a plasma TV, but will save you a heck of a lot more in the long run.
Old 11-25-03, 08:39 PM
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Don't forget footings under the posts. The structural engineer will tell you how big. He'll be much cheaper than the alternative.
Old 12-09-03, 03:30 PM
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Like everyone else has said, this is a job for a pro. If you really feel that you have to do something, I suggest that you put in your poles and jack them just enough to hold them in place. This will help stabilize the situation and you won't be making things any worse. Start saving up and get a pro on this as soon as you can.

Also, don't do any significant remodeling until this problem is fixed.
Old 12-10-03, 07:35 AM
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Put the column jacks on pads made from 2x12. 4 pieces, 2 feet long each, per pad, 2 going one way, the next 2 at right angles. Nail them together. This will give you a 4 square foot area that should provide adequate TEMPORARY shoring. This is a job that should be reviewed by an engineer with timber experience. The footers need to be sized correctly for the type of soil and anticipated load. The biggest problem with jacking against wood is exceeding the crush resistance above the jack. Steel plates are usually required to spread the point load from the jack or pipe column to prevent crushing and additional settlement problems.
Old 12-19-03, 12:03 PM
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A rough rule of thumb for wood's resistance to crush (allowable stress) is 300 psi cross grain and 1000 psi end grain. IF the contact plate is flat AND 4 inches square, that 16 square inches of contact would support 4200 pounds against cross grain and 16000 pounds end grain.

Your situation is most likely cross grain and I doubt 4200 pounds is adequate

So....figure out the capacity of your posts, and attempt to distribute that (maximum) load across a properly sized metal plate that contacts the wood.

For a rough idea of how much weight you may be dealing with, consider each square foot of living space as 40 pounds, and then figure out 'halfway' from the load point.

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