I've got some serious sagging in my floor joists—about 2 inches! I'm looking for tips on how to sister in additional joists. Given the deflection, just hammering the new joist in seems almost impossible. Should I consider jacking up the joists or maybe add a steel beam for support first? Any advice?
2 Answers
Absolutely, you should jack up the joists to address that sag. But be careful—trying to lift the whole 2 inches at once can stress the walls and might even crack them. It's best to make gradual adjustments, around 1/8" to 1/4" each week until you get it right. When you're adding sister joists, use some blocks of wood under the old joists to gain clearance; otherwise, it can be a nightmare to fit the new ones in. I had a similar experience and had to screw my new joists flat against the floor first to create space for later adjustments. Also, keep in mind the height difference in the joists you're using; it can make a difference during installation.
What about jacking up individual joists? I’ve got two that need sistering but one’s already pretty weak from a water pipe running through it. Should I worry about that?
Good suggestion about cutting a beveled edge on one side if you're really tight on space. It makes it a lot easier to fit the sister joists in without forcing them. Just take it slow and you should be able to manage the install fine! It really helps if you can get a buddy to assist too.
Thanks for the tip! I'll definitely keep that in mind as I figure this out.
Totally agree! It definitely requires a bit of patience. Just take your time with the adjustments.