Joist Stabilization

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nafischer90

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Hello,

I recently moved into my first home, built in 1900, SE Pennsylvania. There are some issues with the floor joists in the basement.

The majority of the floor joists are resting on the brick foundation and are in good shape, however around the opening for the stairs the header running along the opening is notched on each end and resting on a ledger nailed to the trimmer on either side. 5 tail joists are attached to the header in the same manner. all 3 ledgers have separated from the supporting member significantly. The header is about 5/8" below the floor on the "bottom" side of the stairs and about 1/8" on the "top" side of the staircase. The floor above has sunk in this location ~1/4" max. The wall directly above shows no sign of recent movement (cracked plaster, molding separating ect) and there is no movement/creaking of the floor so it appears to be "stable" for now. The staircase from the 1st floor to 2nd floor is also right above this area, so it is probably contributing to the overloaded connections.

Joist and Header size: 2.75"x6.75" on 16" centers, notched 3"

Ledger Size: 1 7/8 x 3"

The options I am considering are:

Run beam across all 5 joists and use screw jacks to raise back to proper height level with the rest of the joists then:

a. Build a wall along the edge of the steps to support the header and ledger. The concrete slab in the basement is 4" thick. To do this would I need to cut into the slab and then re-pour a thicker footer or is there a solution that would not involve modifying the slab/floor?

b. Remove ledger, fill notch with packing, and install joist hangers Do the same with the header.

c. Pack space on header to create a flush surface with the ledger and install joist hangers.

Thanks for the help!

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First off welcome to the forum.

Having lived in this generation of house for the last 40 some years (several homes) I can tell you that’s the way they did it and they all end up having stuff like this going on. They cut away half the strength of the beams with those notches and left those sharp corners some times over cut to start a crack. The good news is its been standing 120 years and it is hard to say that about some of the construction done in the 80’s.

You seem to have all the bases covered and although not maybe correct I will tell you what I did with one similar once. I built the wall like you were talking about and I didn’t want to chop the floor out. It should be good and compacted below because it most likely didn’t start out with a floor. I put down a extra wide pressure treated double bottom plate to spread the area and then framed the wall with 2x8 on 12” centers. I think I used 2x10 for the bottom plate. I jacked things back up first on both ends and also pulled the joints tight and plated them with angle and thru bolted. Then I fit the studs one at a time and cut them just a little long so they would go in under pressure. It held fine to this day maybe 25 years now.

Pros will be along soon.
 
If you jack it up you can fill the space above the notch and then add hangers. Spreading the load on the floor is the trick. Best I have found is a chunk of beam. Even if you have to buy something like a 6 x 16 a couple ft long. then set it up with a system against the stairs that will stop it from kicking out because it will want to kill you. You want a piece of steel between the jack and the post so the bottom of the post doesn't compress. Then lift it slow like 1/8" per day. 25 ton jacks from china are cheap and should handle that no problem.
 
I think option a. is you best call. I'm not an engineer, but I don't think you would need to pour footers to support 5 joists. As Bud16415 says I would just make sure that whatever touches the ground is treated. I would attach a 2x8 PT "plate" to the floor and then build a standard 2x4 framed wall that can be slung on top of it.

How far do those joists span until they rest on the opposite wall? The longer the span the more weight your new wall will need to support and the more likely you are to need a better underpinning.
 
Thank you everyone for the input. I appreciate the suggestions to build a wider wall or wider floor plate. With a wall like this should I fasten the bottom plate to the floor? I own a Ramset or I could use Tapcons or similar.

aNYCdb, The joists span 10-11 feet

nealtw, what precautions should be taken to prevent kick out? If the jacks are straight and raised slowly what are the risks of this?
 
Thank you everyone for the input. I appreciate the suggestions to build a wider wall or wider floor plate. With a wall like this should I fasten the bottom plate to the floor? I own a Ramset or I could use Tapcons or similar.

aNYCdb, The joists span 10-11 feet

nealtw, what precautions should be taken to prevent kick out? If the jacks are straight and raised slowly what are the risks of this?
Tie a rope around the post and the stairs, anything that will impede travel.

If the floor doesn't break when you jack it up, you don't need a bigger plate for the wall. Yes you can shoot the plate down. Sill gasket, poly or roofing between wood and concrete.
 
Thank you again for the help nealtw and everyone else. I will post some pictures once I complete the work.
 
So I began jacking up the joists. Everything appeared to be going as planned but then I realized the floor above was moving faster than the wall above. The header the floor joists were attached to appears to be carrying a signifigant amount of the walls weight and therefore the joists are moving up at a faster rate. What is the best solution here? I need to place the support wall directly under the header so in order to jack it up here I would need to put the sill and top plate in place and then jacks in between. My plan was to use a double 2x top plate, but I’m afraid this won’t stand up to jacking so maybe use the same Triple 2x10 I am using as the jacking beam as a header instead of the double top plate?

Sorry a few of the images are rotated. Uploaded from my phone and they rotated on me and don’t see a way to rotate it back.
 
Last edited by a moderator:
After taking up the sag between joists and the subfloor I did about 1/8" per day for a few days. ~1/2 turn of the screw jack in the morning and 1/2 at night.
 
The wall was repaired after the floor had sagged, it looks like you have everything in place now.
It looks like if you build a wall now out of 2x6, that would hold the wall above and the joists below, double stud on each end and 16" on center, the double top plate will be just fine.
 

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