raising a sagging floor

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Old 03-01-07, 01:30 PM
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Question raising a sagging floor

i have an area in my house where the floor is sagging. it's a small one story house with a crawlspace. i am in the process of installing about 4 floor jacks under the house and am curious about the proper placement of the jacks. is it ok to put that many jacks in a small area? i know you are supposed to raise the jacks very little over several weeks.

any suggestions on this topic would be greatly appreciated. thanks!
 
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Old 03-01-07, 03:49 PM
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The jacks are fine, but you will need to pour footings to keep them from sinking into the ground as the weight labors it down. Just wanted to make your day.
 
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Old 03-01-07, 04:27 PM
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If the ground in the crawlspace is solid you might get by with using cat blocks or 2x12's to set the jacks on. It will still sink some but might save you the trouble of a footer.
 
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Old 03-01-07, 06:01 PM
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Cap blocks are cheap work pretty well as footers as long as the soil they are on is consistent and stable (not too rocky or wet). They're usually minimum 2,500 psi concrete, which should be enough to support one or two joists. For the jacks, I like the mobile home type that Lowe's carries because they have a larger foot to spread the load.

Another approach is to use fewer jacks and create a beam across the sagging joists...two or three jacks with a built-up beam or LVL stretching across several joists. Think of a miniature version of the support beam and piers that your joists probably tie into now. Note thatyou will need to properly size the beam so that it doesn't bend at the midde. You may need a more serious footer to carry the added load.

Blocking between the joists is a good idea to keep them from twisting when you raise. If the joists have been sagging for a while and are "set"...they will want to twist instead of straighten out.

No more than 1/8" day for raising to help cut down on damage to members

A few websites that may help:
http://www.hammerzone.com/archives/framecarp/supplement/floor/joist1/raising.htm

http://www.awc.org/technical/spantables/tutorial.htm

http://www.southernpine.com/spantables.shtml
 
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Old 03-14-07, 08:17 AM
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floor jacks

depending on the length you are trying to jack up, Dictates how many jacks to use.you should turn jacks one to one and a half turns a day.
 

Last edited by twelvepole; 05-05-07 at 01:29 AM. Reason: No need to quote entire post to respond
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Old 05-04-07, 11:32 PM
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what is the deflection of the subfloor?
what is the material above?
floor load? is there a 1200# safe above?
what is the construction of the interior/exterior walls/ceilings and coverings?
windows?
moisture content of the soil?
classification of the soil?
type of joists?
size of joists?
composition of the joists?

after floor is level, pour pads, piers, posts, shims if necessary.

moisture in subarea? correct it...

otherwise get ready to do it again later.

80% of the time you can level the floor in one session if the defection is less then 12mm.
 
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Old 07-19-07, 12:33 PM
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house i am about to purchase (discounted) has simular problem

The house i currently have under contract has a simular problem.
It has a half basment, and slab with a crawl space. The sagging is occuring in the center of the house (above the crawl space section of the house) right were the fireplace sits (heavy brick chimminey) all the other floors appear to be level. If i were to hire a proffessional to fix this problem what could i expect to pay, if i did it mytself with help from you guys (i am VERY VERY handy) what should i expect to pay for materials?
 
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Old 07-19-07, 06:24 PM
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Welcome to the forums! Not seeing your problem, we can only guess at a fix. But, generally speaking, leveling a floor is not rocket science, and, therefore, quite DIY friendly. If you are able to acquire several house jacks (ratcheting type is the best). You would need to pour some footings and install either post and beam support or individual posts, depending on the severity and spread of the problem. Give it a shot. We're here.
 
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Old 07-20-07, 06:23 AM
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thank you.

Do you think that if i jack the floor up under the fireplace from the crawlspace below that, it will create cracks in the walls from the movement?

how much of a footer do i need to pour? how deep? how wide? there is not much room down there to do a lot of digging.

im assuming lowes or home depot would have the jacks?

is this common for the floor to sink around the fire place in older homes. It appears as though the entire weight of the fireplace is supported by the floor joists or whatever is under there. i have not gone in the crawlspace that far as of yet.

im just happy that this isnt going to be a very exspensive repair. What would a pro charge to do something like this?
 
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Old 07-20-07, 05:10 PM
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If you make the movement slowly over a period of days, you may escape without doing alot of damage. I would dig out a footing and install 12" sonotubes level with the dirt about 12" deep, and pour concrete in them, leveling them off at the top. After they set up, then you can use the footers as a placement for your posts, and across them you put your beam, then let the house down, slowly onto the beams.
 
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Old 07-20-07, 05:58 PM
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Originally Posted by chandler View Post
If you make the movement slowly over a period of days, you may escape without doing alot of damage. I would dig out a footing and install 12" sonotubes level with the dirt about 12" deep, and pour concrete in them, leveling them off at the top. After they set up, then you can use the footers as a placement for your posts, and across them you put your beam, then let the house down, slowly onto the beams.
i have read horror stories about the jacks kicking out and causing serious injury (i read that on a thread about jacking up a 2 story house that has sagging issues) do you think i run much risk of that being that this hous is only a ranch?

what are sonontubes?
am i using autozone bottle jacks or are there jacks made specifically for this type of job?

thanks so much you guys are the best.
 
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Old 07-24-07, 01:15 PM
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I'll give you an estimate of what it costs just to do a "study" of sagging floors, tilted foundation, and cracked walls in Hawaii. The engineers (structural and soil) want between $5000 - $7000. Yesterday they drilled three holes outside to do core samples. It took most of the day, and I'll get a geological report in a month. The second visit by the engineer will take place in 2 weeks and he will do a floor level survey, and visual inspection of the crawl space and surrounds. He told me that the report he generates can be given to a contractor to jack up the house to original specs and/or just re-pin the house. How much will it all cost? As much as $70,000 for all the work, including new footings, piers, bracing, etc. That's a worst case estimate on my part. Who knows? It could be worse. If I knew what I know now, I may have avoided buying a home at the discounted price. Because, there's nothing like a buyer who is in way over his head in knowledge and experience. That's me, Mr. Know-it-all. The wife is kicking me every day - "I told you so!"
 
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Old 07-24-07, 04:25 PM
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The jacks have to be level and plumb to prevent kick out. Bottle jacks can and do leak down, so I prefer to use a ratcheting type house jack. Found some at a garage sale on day for a buck apiece. The ratcheting type have a broader base, too.
Sonotubes are wax impregnated cardboard tubes sold in different diameters and lengths at most lumber yards. You dig your hole, put some gravel in the bottom, fill it with mixed concrete, screed off the top and you have a column of concrete on which a load can be placed. Different parts of the country have varying frost lines. Up nawth it can be up to several feet, while in Florida you can almost use ground level, so check that out locally.
 
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Old 07-25-07, 09:08 PM
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Originally Posted by chandler View Post
The jacks have to be level and plumb to prevent kick out. Bottle jacks can and do leak down, so I prefer to use a ratcheting type house jack. Found some at a garage sale on day for a buck apiece. The ratcheting type have a broader base, too.
Sonotubes are wax impregnated cardboard tubes sold in different diameters and lengths at most lumber yards. You dig your hole, put some gravel in the bottom, fill it with mixed concrete, screed off the top and you have a column of concrete on which a load can be placed. Different parts of the country have varying frost lines. Up nawth it can be up to several feet, while in Florida you can almost use ground level, so check that out locally.
i am in NJ i am really hoping that i dont have to dig out a hole about 6 feet deep in a freakin crawl space that i can barely crawl in. But wait being that the crawl space is already about 4 feet below ground level i wont have to go much further maybee just a foot especially since its directly under the living room. maybee 1 feet or 2 feet deep? am i correct to assume that?

i dont think the problem is as major as the one you mention abe. the rest of the house is level abe. its just floor around the fireplace thats sagging some. It may have been improperly installed as someone else mentioned. i am sure that jacking and supporting will do the trick.

i couldnt pass on this house. largest lot in the neighborhood and the taxes reflect that of a average size lot. plus im getting it at a 80k discount off the listing price, actually paying a bit less then the owner paid 3 years ago.
 
 

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