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Jungle 07-11-2013 12:50 PM

Warped floor joists, floor leveling
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Look at this joist is warped, starts at 17.5" then to 14" with the small blocks to 17" at the end to the wall. Weird? It could haven't been originally built like that, so it must of warped, sloped the floor then they decided to fix it by installing the cross blocks?
I'm jacking up the floor now, i bought 4 screw jacks today and need about 6-10 more. I have to support most of the floor joist it seems.

Should i take out the old cross block and jam in new 15+" 2x6" in there and try to unwarp the beam? Maybe i should do this before i start jacking it up?

nealtw 07-11-2013 03:40 PM

Yes it was likely built like that. The angled bridging is nailed from above and then the subfloor is nailed down. It is up to that guy to straight the joists as he goes and then the bridging is nailed from below. You don't see much of this in newer houses because the joists have to be kept straight to have the plywood fit. The shiplap was very forgiving for the inexperienced carpenter.
If you are planning to leave these post in place, it would be far cheaper to just build a wall to the right height.
I would have like to see a 2x4 or 2x6 running under the joists above the posts, if everything isn't kept level or plumb there is a chance that a joist could fail with any angled load which would have a post coming out sideways in a hurry.

CallMeVilla 07-12-2013 12:34 AM

Believe it or not, in my starting out days, I encountered twisted joists due to water damage from a bathtub which had repeatedly overflowed. After demolishing the floor above the joists, I took a brute force approach ...

I had 1/4" steel plates fabricated the height of the joists with pre-punched holes. I drilled through the joists and sandwiched the joist with 1/2" through bolts and washers. By ratcheting the bolts, I squeezed the joists back into true and enormously strengthened the floor system. Then it was easy to reinstall the floor and the redesigned bathroom.

Did it all with cheap re-conditioned power tools I bought at a Sears Outlet store. Those were the days. :D

Jungle 07-12-2013 05:04 AM

"If you are planning to leave these post in place, it would be far cheaper to just build a wall to the right height."

I still have to jack up the floors. The floors slants inward to the main support beam caused by excessive weight of above walls + years of high humidity. Building a wall would only support it and still require jacking in the future. It might be cheaper but not in labour hours @ $52 a jack post it only take 10 minutes to install and last forever.
Jack posts are also required by inspectors, a wall would look suspicious.

"I would have like to see a 2x4 or 2x6 running under the joists above the posts,"

Each Joist needs to be raise differently, i don't think i can just raise them all the same.

I check above the floor where the joist warping is and sure enough it is about 1/4" depressed. Still wondering if i should try to unwrap it or not? Or use some floor leveler?

As the floor jacks up it will become less noticeable.
I have to buy another 5 jack posts today. I am really pissed off i didn't do this in the first place.

nealtw 07-12-2013 06:30 AM

Do not remove the cross braces they are holding the joists perpindicular. The nails in the subfloor would have to be pulled in order to straighten the joists sideways and that has nothing to do with the sag.
Are you intending to leave these posts in place when you are done or are you going to look for as way to keep the joist up with out the posts?

bud16415 07-12-2013 10:25 AM

What you are showing is a telescoping Lally column support. It is not a house jack and isn’t intended to be one. Building code varies but I believe the telescoping ones are intended for temporary support and at very least have to have a footing below them and should be imbedded into the footing and the beam above to keep them from kicking out.

Your floor sheathing is nailed into the joists and would have to be removed if you want to straighten anything out.

I would be very careful about trying to correct too much too fast.

If the problem is a low area in the floor but the floor is stable and you don’t feel a bounce I personally would level it above. If it has bounce or you have reason to believe it is getting worse then you should do something to stabilize it and or lift it. Putting a dozen Lally columns under the room is not my first choice.

Jungle 07-12-2013 10:51 AM

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"Are you intending to leave these posts in place when you are done or are you going to look for as way to keep the joist up with out the posts?"

As Bud says you are suppose to have proper footers cut into the concrete flooring etc. But these metal post jack are perfectly fine, it even says on the box can be used for permanent foundations. Wood posts would be a red flag for an inspector.

When i'm finishing raising them i will attach some blocking to the side of joist and screw it right to the top, so at least i won't coming flying out at someone.

The problem is yes the above floor is a supporting wall and other structural points are sinking and the floor is slanted as well as the beams on the ceiling are slanting down as the wall is sinking... So these support are required.

I wonder if i should try to jack up the main support beams as well, the beam looks straight but the support look to be slightly bent probably from too much pressure coming from the left...?
You can see all those joists on the left are sagging need jacks. The bathroom walls and staircase are 3' to either side of the main support beam.

nealtw 07-12-2013 06:55 PM

Let's get some language straight.
A barring wall in the basement will have a footing, ( a footing for a wall will be something like concrete 8" deep and 16" wide running the length of the wall)
The barring posts that is showing in your photo will have a footing, something like 10" deep and 24" sq under the floor so you can't see it.
Most basement floors are 3" to 3 1/2" thick and will not support a great deal of weight before it breaks thru.
There may be walls above this sag but they should not be barring walls, but they may be and that should be figured out.

"IF" you are lifting a great deal of weight the proper way to do this would be to cut a hole in the floor at each end of the sag put a beam under the joists and jack it up and then set it on post between the beam and the footing.
"IF" you are just raising the floor without any extraordinary weight above you can just build a wall to support the floor off the foor.

"IF all your joists are the same height like 8" or what ever you could nail a 2x4 the bottom of them and when everything is jacked up and level the 2x4 will be straight.
I think a row of posts would be more of a red flag that a wall built with a bottom plate and two top plates, and actually I would use 2x6 to help spread the load on the floor.

Jungle 07-13-2013 12:20 PM

"In housing, load-bearing walls are most common in the light construction method known as "platform framing", and each load-bearing wall sits on a wall sill plate which is mated to the lowest base plate. The sills are bolted to the masonry or concrete foundation."

Someone told me that the basement was made with a lot of concrete and would be a major job to cut through the concrete, so think the jack posts are a reasonable solutions. The more posts the less load on each posts. If you think the concrete will crack maybe i should but a large metal plate as a base?

I guess this footing won't work would it?
Each beam is different shapes and width, i don't think it is a good idea to lift them all at the same time.
There is about 2" of sagging, i can try slowly slowly.

Keep in mind, the wet basement is now solved which is the cause of the sagging, the house has stood up this long.

Once it's jack up a bit i can sister another beam on there and few more blocks will make it plenty strong.

GBR 07-13-2013 02:32 PM

No, those deck pier blocks won't work. You need a footing of proper size to carry the load from above. (eg. footing sizes; Structural Engineers are enlisted to supply this for the liability involved, because of the bearing wall offset from bearing below past maximum distance of Code (depth of joist); a lateral tie across the joists at jacking area to keep them in check, as Neil said.

May want to add "old work" joist hangers to all joists as no ledger is present to even pass minimum code;

Add solid blocking to prevent rotation over the new wall/footing; Need a larger steel plate under built-up beam (3 joists) to spread load to post cap.

They are all different depth/width because of being milled before "standard" sizes were established. We can only give you our many years of experience in building trades (39 for me) and safety concerns, up to you - what to follow or not. Build safely.

PS. The adjustable may pass inspection here---- if welded closed (and dipped/painted against rust--non-movable); check locally.

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