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Sagging floor joist & crawl space jacks

alex3610

Well-known member
Joined
May 18, 2011
Messages
60
Location
Midlothian, VA
I realize this is getting a little off topic from Garage stuff but I have learned far more about building construction topics on this forum than anywhere else. A true wealth of knowledge!

Anyway, here's the problem. My house is built on a pier and beam foundation over a dirt floor crawl space as is common in the south east. (Richmond VA area). I have a low spot in the floor at one end of my house as well as a few doors where the doorway seems racked and they don't close properly. My area is notorious for shrink/swell soil and the foundation issues that it creates. So I have always assumed that was what I was dealing with. Recently while poking around doing some recon for an upcoming electrical project, I realized I had a floor joist that is sagging at least an inch in the center. It's hard to explain without a picture but it seems like the last pier at this end of the house was maybe 8" shy of being under this joist. On the other side of this joist the foundation gets narrower for a bump out on that side of the house and no piers are needed. So either the pier was placed in the wrong spot, or some other solution should have been used here.

It's also worth noting that this is where about half of the electric service for the house is running so sistering another piece of lumber to this joist would be a huge pain in the ***. I am thinking what I need to do is use some sort of crawl space jack that will be underneath a beam that runs perpendicular to the joist in question. My thinking is that I need to have the beam at least capture the joists on either side of it so I know when everything is square again.

My concern is what do I put underneath said crawl space jack? As I mentioned we have marine clay / shrink-swell soil so I already don't have much faith in the dirt underneath me. Some have suggested some sort of special gravel to fill in a hole and then a concrete block on top of that. It's difficult to find much information as most of the contractors that specialize in this kind of work don't seem interested unless its a $45,000 job (JES) so they can pay for their TV ads. It seems like a very doable DIY project.

So I need to know:

What do I need underneath the jack?

What type of jack? (Remember this will be a permanent installation as I can't easily sister the joist)

How slow do I need to go when jacking up the joist?

Thank you in advance!
 
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alex3610

Well-known member
Joined
May 18, 2011
Messages
60
Location
Midlothian, VA
www.mudsupply.com/Simpson-J57-Jack-Pier-5-7-In-p/8013.htm

Or... https://sep.yimg.com/ca/I/yhst-4829792992329_2270_968770223

Use these on top of pre-cast concrete piers. Of course with your problem soil, you will need to dig down to good base or constantly adjust these.

Yeah the more I think about it the more I am realizing I have to dig down and establish a firm base otherwise like you said I will be back down there all the time jacking it back up a little as it pushes down into the earth. Thanks for the links.
 
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BillK

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Aug 24, 2006
Messages
9,324
Location
Beautiful Southern Maryland
A friend of mine just went through this with an old house he bought. They ended up digging holes and pouring footings for each pier, jacked the house up and installed new support piers.
 

greenlizard

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Joined
Dec 4, 2012
Messages
186
Location
Chapin, SC
Been through this a couple of times, sinking piers, insufficient piers. Will be doing it again with my current sixty year old house in SC. Dig down to solid soil (or rock) and pour a footing. Major pia under a house but not complicated. You can use a Sonotube to get a nice looking foundation. A steel house jack can be used as a permanent fix in my area, might be easier than setting block. When you jack up your floor joists do take your time. Maybe raise it half an inch every other day or so. Otherwise you will crack walls from the floor movement. Best of luck.
 

pop pop

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Joined
Apr 1, 2010
Messages
2,859
Location
Virginia
I live in your area. Dig down far enough the moisture content will not vary. That's going to be fairly deep.
 
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