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Old 11-20-2017, 01:19 PM   #1
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Jacking up Floor and bad Joists


Just a bit about myself: I lay floors, hardwood, tile etc and did about a year of commercial framing and hanging (nothing structural, just slapping up tin) and a decent amount of mechanical knowledge and experience from this to that and so on. I am a competent person and by no means a moron.

So I have gutted a previous remodel attempt in my new home and found it to be in worse shape than expected and need some advice.

I have attached a rough drawing of the basement below, you will see Green Lines being Joists that rest on foundation and Pink Lines as Joists that do not. The area circled in Blue Marker is the affected area I will be referring to.

The bathroom is above the affected area and is pretty sketchy. I plan on raising the floor back up and replacing some bad Joists as well but need a little advice as Ive never done this before.

I have been looking into Jack Posts to raise the floor, and it seems as though I should use multiple Posts set underneath a beam (2x6 or the like) to span across the affected area. Here is an example of the method I would use at about 2 minutes into the video:

1. Can I go about this method of raising slowly over a matter of say 2-4 weeks or more (depending on how much it needs raised), or should I absolutely contact an engineer for this?

2. Or would you suggest other methods or equipment?

I also plan on replacing the heavily affected Joists so the floor can hold itself up again using a method such as this:
http://homeguides.sfgate.com/replace...ist-25638.html

3. Is this possible without having to pull any carpet or hardwood upstairs?

Youll also see what looks like some rotting floor boards to me, should I replace these as well? (I plan to remodel the bathroom eventually too so I can replace them during that project)

4. Do these need replaced or are they ok to stay?

If anyone is interested about how this previous remodel was done it was 2by's cut down into 1/2" rips and Liquid Nailed to the foundation without a coating or barrier, that and the grade outside of this wall was running into the house as well.
Attached Thumbnails
Jacking up Floor and bad Joists-img_1522.jpg   Jacking up Floor and bad Joists-img_1512.jpg   Jacking up Floor and bad Joists-img_1518.jpg   Jacking up Floor and bad Joists-img_1525.jpg   Jacking up Floor and bad Joists-img_1531.jpg  

Jacking up Floor and bad Joists-img_1540.jpg  
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Old 11-20-2017, 01:40 PM   #2
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Re: Jacking up Floor and bad Joists


Water proofing is done from the outside so fixing slopes and down spouts is first on the list. Wood should never directly touch concrete.
A wall would be better than a post as it spreads the load better any real weight being lifted might need a footing below the concrete more so with a post than a wall.
I would like to see pictures of the framing that you want to lift.
Any where the joist stop short of a bearing wall they should have hangers off a double header the double header should have hangers to a double joist on each end of the header.
The wood may look bad but can be judged by poking it with an awl, ice pick, or screw driver. May want to be beefed up for new floor anyway but mostly can be address when the bathroom is stripped out.
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Old 11-20-2017, 11:10 PM   #3
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Re: Jacking up Floor and bad Joists


I understand what your saying about the water proofing.
Every single floor joist in my basement touches concrete, see picture #1 attached.
The plan is to correct the sagging before putting up a support wall and replacing a few joists as well.
My thought was to use 2 or 3 jack posts under a 2x6 "beam" to correct the sagging floor do you think that would disperse the weight enough?
I don't know why all of the picture got turned around but if you flip picture #4 of the first post Clockwise you will see the exterior wall on the right, above is what I am talking about.
Below the bedroom the hangers are lacking any intended integrity and need to be replaced, I assume this can be done similarly to the bathroom so I decided to focus on just that not to confuse the situation.

Pictures:
1. Joists resting on foundation
2. Above broom handle and DeWalt bag is the affected area
3. From the other side of the room affected area is past the stack
4. How multiple joists are resting on the foundation
Thanks

Edit: some of the photos are flipped around again any lumber you see are the joists in the ceiling
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Jacking up Floor and bad Joists-img_1543.jpg   Jacking up Floor and bad Joists-img_1544.jpg   Jacking up Floor and bad Joists-img_1545.jpg   Jacking up Floor and bad Joists-img_1553.jpg  
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Old 11-20-2017, 11:35 PM   #4
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Re: Jacking up Floor and bad Joists


When we finish basements we build a 2x4 wall just in front of the foundation. Usually the footing for that wall is wider than the wall is right under the floor so that wall built tight would be a bearing wall. Then you could deal with the rot up there from the outside, maybe.
One easy way to lift the floor is to put up the top plate and the bottom plate down but leave the bottom plate a little long. Figure out what the studs would be if the floor was level and cut the studs to that. set the studs on an angle and screw the tops in place. with a heavy hammer tap the bottom a little every day until the studs are up straight and the floor is level.
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Old 11-22-2017, 09:17 PM   #5
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Re: Jacking up Floor and bad Joists


Can't offer much advice on this, but yes raise it slowly over a course of time. The reason I am commenting here is to warn you on the post jacks, make sure they are safe and secured so they cannot kick out too far. I heard one kicking out one day in a friends basement, thankfully we were upstairs. It sounded like a tree hit the house or a bomb went off. A flying jack post could easily kill someone, so use extreme caution when working near them or with them and keep people especially kids out of the basement until everything is completely secure and safe.
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Old 11-23-2017, 01:42 AM   #6
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Re: Jacking up Floor and bad Joists


^^^ what he said ^^^

Plus, since the jacking locations are not designed to carry a point load, use some wood blocking under them to spread the point load from the bottom of the jacking post over a larger area.
A 16 x 16 piece of 3/4 inch plywood with alternating layers of 2 by ? material covered by another layer of the plywood should do it quite nicely.
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Old 11-23-2017, 05:13 AM   #7
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Re: Jacking up Floor and bad Joists


If you are going to use the jack posts as a permanent fixture, the proper way to do it is to cut the current concrete floor post location in a 12" x 12" square, remove the square, dig down at least 12", lay in rebar and fill the hole with concrete grout, not just pre mix stuff. The grout is a harder product and the size of the footing will handle the point load better than just the slab, which will eventually fail.
https://www.homedepot.com/p/Quikrete...0481/206596944 will provide good strength.
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Old 11-23-2017, 12:22 PM   #8
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Re: Jacking up Floor and bad Joists


Quote:
Originally Posted by jlhaslip View Post
^^^ what he said ^^^

Plus, since the jacking locations are not designed to carry a point load, use some wood blocking under them to spread the point load from the bottom of the jacking post over a larger area.
A 16 x 16 piece of 3/4 inch plywood with alternating layers of 2 by ? material covered by another layer of the plywood should do it quite nicely.
I like the idea for covering a larger area, this is good advice.
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Old 11-23-2017, 12:30 PM   #9
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Re: Jacking up Floor and bad Joists


Quote:
Originally Posted by chandler48 View Post
If you are going to use the jack posts as a permanent fixture, the proper way to do it is to cut the current concrete floor post location in a 12" x 12" square, remove the square, dig down at least 12", lay in rebar and fill the hole with concrete grout, not just pre mix stuff. The grout is a harder product and the size of the footing will handle the point load better than just the slab, which will eventually fail.
https://www.homedepot.com/p/Quikrete...0481/206596944 will provide good strength.
Once I address the sag and replace a few floor joists and hangers I will be removing the chimney on the second floor of the house. The attic is already finished so Ill only be doing some patch work and Ill be ready to address the center wall in the basement. I plan on removing it and replacing it with a post or two (I haven't consulted anyone or done any math yet), in which case I will probably need to do this.

I should be able to poor a footer in the area that's been excavated by the removal of the foundation wall, correct?
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