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Discussion Starter · #1 ·
I recently bought a duplex, and the upstairs unit's kitchen had this floor that was built up, with what looked like floors being built on top of old floors. I'm lowering it to level it with the other floors in the house, and gain more ceiling space in the kitchen. The kitchen floor was about 4" higher than the rest of the house's floors.

After doing demo work - surprise! That 4" raise was a previous homeowner's attempt to level and hide sag in the floor. So now I have this sagging kitchen floor, and I'd like to level it a more professional way.

I know jacking the house is an option, but with a 4" sag I feel like jacking that much is going to cause way more problems and I am uncomfortable doing it.

I've read that scabbing is another technique too.

Finally, can't I just rip up the kitchen subfloor and replace each of the joists? I'm not sure if I'd have to go into other parts of the house. Is sistering those joists an option?
 

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Discussion Starter · #4 · (Edited)
Any pics? What are the dimensions of the room, namely the joist length? I find a 4" sag in the middle of a room hard to believe without some other failure taking place.
Kitchen is 10x12, with joists in the basement at a 21' span. House was built in 1900 and relocated 1920 to a different plot. There was some joist termite damage several owners ago that was repaired.

Pictures coming...
 

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I'd be prepared to jack it up slowly over time and have plenty of issues in adjoining rooms if you really want to take care of it right. Would you be able to set jack posts directly on the foundation below? Are adjoining rooms updated with drywall or modern materials, or lathe and plaster? Either of these would have to be repaired or replaced after jacking it up. If wood paneling or tongue and groove planks I'd be tempted to jack it up a few cranks at a time and let it settle before proceeding. No more than 1/4-1/2" in one "session", and let a few months go by before having another go at it.

My office is in a 19th century building where the joists span about 25', with a center beam on 12x12 posts on footings in the basement. However, my office is on the second floor where the joists span the same distance, but only have 3 metal posts holding up its entire center beam. There was so much sag when I moved in that I volunteered my own time to rip out the old floor and use floor leveler to make the area my desks would sit at level. Otherwise I would have had a 1 1/2" drop over 9' with an L shaped desk. I made sure the landlord knew I wouldn't stand for it, even if no one had complained before. We looked at other options as far as jacking up the center of the second floor, but nothing else was feasible. As it was I added 80-100lb of the stuff after having the structure inspected.

I think you'd probably want it inspected anyway. If there's any remaining structural damage an expert set of eyes can see where you might need to add a beam or permanent supporting post to bear the load.
 

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Are you sure after removing all the 2x4's that are laid on the flat that it isn't as extreme a sag as you indicated? Have you measured it with a laser or anything that would let you get from corner to corner? I'd think you'd have noticeable issues with the ceiling below if it was really that bad. Those pics make it look like a ton of work, good luck!
 

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Discussion Starter · #8 ·
I'd be prepared to jack it up slowly over time and have plenty of issues in adjoining rooms if you really want to take care of it right. Would you be able to set jack posts directly on the foundation below? Are adjoining rooms updated with drywall or modern materials, or lathe and plaster? Either of these would have to be repaired or replaced after jacking it up. If wood paneling or tongue and groove planks I'd be tempted to jack it up a few cranks at a time and let it settle before proceeding. No more than 1/4-1/2" in one "session", and let a few months go by before having another go at it.

My office is in a 19th century building where the joists span about 25', with a center beam on 12x12 posts on footings in the basement. However, my office is on the second floor where the joists span the same distance, but only have 3 metal posts holding up its entire center beam. There was so much sag when I moved in that I volunteered my own time to rip out the old floor and use floor leveler to make the area my desks would sit at level. Otherwise I would have had a 1 1/2" drop over 9' with an L shaped desk. I made sure the landlord knew I wouldn't stand for it, even if no one had complained before. We looked at other options as far as jacking up the center of the second floor, but nothing else was feasible. As it was I added 80-100lb of the stuff after having the structure inspected.

I think you'd probably want it inspected anyway. If there's any remaining structural damage an expert set of eyes can see where you might need to add a beam or permanent supporting post to bear the load.
I really, really don't want to jack the house. Joists are undersized, and I want to sister them with more lally columns to reinforce and make sure there is no future drop. The whole house is wood and plaster, and I know there is going to be a ton of additional problems if I do it. The first floor has very minimal sag, the second floor kitchen has more of it, and if jacking is the only way to fix it I'll just live with it vs. making this a money pit scenario.
 
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