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Old 05-30-2017, 01:05 PM   #1
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Adjusting a Jack Post


I have an issue in my home where there is about a 10 foot stretch of floor over the main i-beam that is raised up about an inch or so. I had a structural engineer come look at the issue and he indicated there isn't anything structurally wrong with the house and that I could just adjust the jack posts in the basement. Probably should have asked him while he was there, but it slipped my mind.... How do I adjust the jack post? There's a hole in the screw, but I was told there should be a nut. There's a cap at the top of the post that has a spot weld on it, was wondering if the nut is under there or do I just stick a steel rod through the hole in the screw?
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Old 05-30-2017, 01:06 PM   #2
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Re: Adjusting a Jack Post


1st Post so I can post a pic of the post...
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Old 05-30-2017, 01:07 PM   #3
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Re: Adjusting a Jack Post


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Old 05-30-2017, 01:20 PM   #4
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Re: Adjusting a Jack Post


Usually these posts are a cap, a jack, a post, and a base. They are put in, plumb, where needed and the jack is engaged by rotating the screw until the beam above is at the position needed. I suppose your's could have been welded so the screw wouldn't (?) turn. But you can try slipping a large pin (as a substitute for the jack handle) in that hole and CAREFULLY back the screw down. CAREFULLY, you are dealing with a multi-ton load.

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Old 05-30-2017, 01:31 PM   #5
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Re: Adjusting a Jack Post


A large pipe wrench on the unthreaded part will do a good job on that.
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Old 05-30-2017, 01:45 PM   #6
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Re: Adjusting a Jack Post


Has this floor been raised since the home was built, or was this just noticed?

You say this is your main beam. I assume the ends are in beam pockets. Is the beam itself level, or was the hump caused by something else? Have you considered what other areas of the home the lowering of the jack post would effect?

Something just sounds off with this idea.
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Old 05-30-2017, 02:33 PM   #7
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Re: Adjusting a Jack Post


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Originally Posted by ZTMAN View Post
Has this floor been raised since the home was built, or was this just noticed?

You say this is your main beam. I assume the ends are in beam pockets. Is the beam itself level, or was the hump caused by something else? Have you considered what other areas of the home the lowering of the jack post would effect?

Something just sounds off with this idea.
I just purchased the home and pulled up the carpet to install hardwood floors when I noticed it. Wasn't as noticeable with the carpet given the thick pad that was put down (probably to mask the issue). However, the rest of the house is basically flat no rises and the highest area is right above two of the jacks. Structural Engineer noted that this was not something that happened recently, it would have taken years. The hump is essentially being caused by the joists being pushed up by the beam they're sitting right on it.
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Old 05-30-2017, 03:20 PM   #8
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Re: Adjusting a Jack Post


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Originally Posted by sboisvert7 View Post
Structural Engineer noted that this was not something that happened recently, it would have taken years.
You will need to take your time in adjusting this hump back down. Do it very slowly, as in tiny increments over the course of months if possible.
If you just drop it an inch all at once you'll wind up with cracks and squeaks all over the house.
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Old 05-30-2017, 03:46 PM   #9
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Re: Adjusting a Jack Post


I can't tell from your post if you paid a professional engineer to investigate and report on the cause of the hump, and offer recommendations as to how to repair the problem, or whether you got an advisory opinion at no cost from perhaps a friend.

If you paid the engineer to recommend a solution to the hump problem, I suggest you call them and ask for a detailed procedure to correct the problem. This thread seems really odd to me, especially the part about how the hump developed over a long period of time. Standard practice with jack posts is to install the jack post such that the beam is level, I have never heard of deliberately raising the jack post to create a one inch hump.

Further, jack posts are normally locked into final position either by welding or deliberately damaging the threads so the post will not move over time. The fact that you apparently have a one inch hump in a main beam suggests that either the post was incorrectly installed, or the walls have settled. In any case, your engineer should have studied the reason for the hump, and presumably issued you a report on the problem. Before you get involved in backing down the jack, you absolutely need to carefully study the problem, and determine if the jack height can be changed. Further, you need to talk to your structural engineer, allowing a main beam to settle an inch can cause all sorts of problems with floors and walls, and needs to be done very carefully.
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