Floor joist lower than others


Old 04-21-06, 12:30 PM
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Floor joist lower than others

I have one floor joist in my basement that sits directly under a first floor wall. This first floor wall sits directly in the middle of the 2nd floor bathroom and under the bathtub and is just about dead center in the house. The joist was, perhaps, 1/4 inch lower than the others. I used a floor jack to raise it up and put a 2x4 under it on the foundation wall, next to the sill. It worked but was a heck of a lot more difficult than the other floor joists I was leveling (due to minor termite damage).

However, this one joist has now dug itself into the 2x4 about 1/16 of an inch and my upper floors still show a slight bend near those walls. I presume these walls are not load bearing since they run parallel with the joists.

I thought this supported the 2nd floor bathroom wall because there is a hump in the middle of the door preventing it from closing. Turns out not to be the case and raising the joist may have made the problem slightly worse, don't know.

Even crazier is I have a hump by the back door, which has always been there making the door rub along the carpet. Taking a level along the joists shows they are pretty level but one or two may be 1/16 to 1/8 higher than the others. I thought they should all be the same.

Like I said, I had some termite damage around my rear door and along the plate where this occurs. That is why I raised these joists and put new 2x4s under them.

I hope you understand my confusion and can clear up some for me.
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Old 04-21-06, 07:35 PM
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If the floor is level, why would you raise a joist? 1/8" is not an amount to be worried with, and raising it could cause the flooring to crack or otherwise get out of alignment. The floor jack will dig into the 2x4 because the 2x4 laid on its side is softer than the concrete it is sitting on. And the pressure YOU put on it is causing it to indent, not the pressure from the floors above. Otherwise the indentation would be the original deflection, plus the amount you jacked it. Remember you jacked it up. In addition, framing lumber can vary up to 1/4" in width, so a 2x8 can be 7 1/4-7 1/2" in width. It will drive you crazy sometimes.
Old 04-21-06, 09:30 PM
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I didn't say the floor was level. In fact, the reason I raised it was the floor was not level and that's when I found the joists sunk into the original plate.

The floor jack didn't dig into the joist. The joist dug into the 2x4 I put under the joist and only the problem joist did this, not others next to it.

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