Upstairs Floor Joists sagging

[yooper]

I just purchased a 2 story home. The 2nd story floor was framed with 2x8's spanning 14 feet. a plumbing contractor cut out the middle of a 2x8 about 7' in from one end... about the middle of the lower room span.
Over the years, the floor has sagged approximately 1.5" at the worst in the middle. The lower room is 12x14... so the flooring above this area sags and pretty much tapers to the 1.5" sag equally... I'm just starting to repair this, but normal "jacking" with hyrdaulic jags, timbers, and beams isn't working so well.. need to rethink.. the doors upstairs and flooring is really sagging bad... I believe jacking the 2x8's straight, and sistering them or just installing new joists is the way to fix.. need some help rigging and jacking from below to fix... the ceiling is open as all drywall is removed.

[jnaas2]

Im currently repairing a commercial building in worse shape then what you are talking about. If this floor you are trying to raise is the center of a room upstairs this should be no problem, but if this span includes a supporting wall then the game plan changes. Its next to impossible to raise a supporting wall 1 1/2 INCHES all at once let me know for sure what you have. A supporting wall caries the weight from the roof to the foundation and can go thru floors and walls till it gets to the foundation

[HayZee518]

the plumbing contractor should have been smarter than just cutting out a section of ANY floor joist. the dead ends are usually bridged by another short piece of what ever 2X and nailed into adjoining joists to keep the load intact.

[pushkins]

How big hole did the plumber cut ?
If there is plumbing going through this joist how do you plan to sister a new joists to it ?
All holes in any floor joist must be set back a min. of 2" from either the top or bottom edges of the lumber.
The rule of thumb for jacking is to raise it 1/4" - 1/2" every couple of days, this helps alleviate any further cracking upstairs.
Once you get it nice and level, like HayZee suggests you should build a header on either side of the "plumber cut out" to join the joists on either side of the cut joist to the cut joist.
As jnaas2 said, if there is a load wall above or very near this particular joist then the game plan will need to be revised.

[yooper]

In response to jnaas2... it is more complicated. there is a dormer wall almost directly above where the joist was cut out... The area on the first floor is a kitchen.. the area on the 2nd floor is the corner of the dormer wall and a bathroom...

Really need help setting up and rigging to jack this area correctly...

Thanks

[pushkins]

The dormer is immaterial to this joist unless there is a wall that is above the effected joist.
Dormers tend to spread the load to an outside wall not floor joists.

[jnaas2]

Pushkins is right on a dormer carring the weight to the walls, now if there is a wall thats connected to where the dormer is located they may have carried some of the weight thru to the floor joist. Its hard to say how they framed the house without tearing part of it apart. And as hayzee said the Idiot plumber shouldnt have done what he did. To fix the problem You need to take at the least 3-2x12 nail them together to make the beam to jack up on. They will span the distance of the floor area that you are going to raise. Now the next thing thats important is to go downstairs and make sure what direction the floor joist are going, that you plan on using to support the floor jacks that will lift the load. Now go back down stairs and lay a 4x4 by 4 feet long on the floor below to carry the weight over several floor joist and if needed lay a piece of plywood down to help protect the floor finish downstairs. You may damage the floor downstairs in the process ofn raising the upper floor. You will need a jack about every 5 or 6 feet depending upon the load which when you start to try and pick it up the jacks will let you know how much load they have on them by how hard they are to screw up. I use the adjustable screw jacks like you find in basements noot hydralic jacks which you can load up with too much pressure and do physical and structual damage with. One other thing if the load you are trying to pick up is a lot you may need to go downstairs or in the crawl space and support the lower floor. When you start to raise the floor go slow and dont try to push up to fast its taken years to settle and you cant pick it back up in a few hours. Sometimes you cant pick it back up at all only stop it from sinking more