How to support sagging ceiling joist and level uptairs floor?

Hi Jim how I would deal with it is with added beams and posts for additional support. Firstly, you will need to jack up your second story with jacks and beams to get it level again and then add in your new support beams and posts. This youtube video should help: https://www.youtube.com/watch?v=KpQ1rK3fb-8 It can be pretty dangerous!

I would get a pro. The joists may be cracked. Too much weight on top of them could crack and/or warp them. They may not be properly sized to carry the weight. Knee walls aren't heavy enough to cause them to sag if they are the proper size. Don't try to do anything yourself if you don't know what is causing them to sag. You can cause more damage.

Hi! I agree with William that you need a professional for a project like yours. Make sure they are licensed and insured. You don't want to damage your house or risk injury.

The correct way should be to take the hole ceiling down and re doit because you don’t know what the rest of the supports look

ike for it to be that way .

You coukd use 2 x4 s for supports or get 4x4s

This is definitely a situation for a structural engineer and a contractor as you there's a lot going on here. Hands down, it's best handled by the pro's so your house doesn't fall down.

Knee walls are not sturdy enough to support what you have going on, you may have sagging and cracking and be compromising the integrity of your project. Bring in a contractor, licensed and insured.