The rim joist on the front of my house has water damage and needs to be replaced. When I pulled off most of the rot, less than half the board's thickness remained. The floor is cantilevered about 3 feet. The joist is a 2x10 about 13' long. I originally was going to sister in a replacement for the damaged area but my neighbor (a city inspector) said that if it were his house, he'd replace the whole board. And since I have the entire board exposed right now anyway, I figured I might as well. What I don't know is how be sure the house doesn't shift while I replace it.

I haven't noticed any dip in the floor inside. There is nothing especially heavy in the bedroom over the cantilevered area (no piano or anything like that).

I was thinking I'd put temporary 2x10 blocking between the floor joists and then pull out and replace the rim joist. Is that safe or do I need to somehow put the floor on jacks? Can I also replace the rotted section of the bottom plate at the same time?

enter image description here


1 Answer 1


I can think of a couple ways you might go here. The rim joist doesn't carry much actual load. Most of it is on the common joists. Really, you can remove it and replace it without doing much else. Keep an eye on things as you do so and watch for any twisting movement in the in the joists.

Another approach would be to rip cut the joist halfway down and replace it with two boards. Remove the top half and replace it with a 2x6, then remove the bottom half and replace it with another 2x6 ripped to the correct dimension.

  • Agree with the first paragraph; not so sure about the second. (Premise being that they built it with a 2x10 deliberately; without engineering too hard, I'd want to replace in kind.) Oct 7, 2017 at 14:48
  • The floating rim is a 2x10 because the other joists are. Doesn't mean it's a structural necessity.
    – isherwood
    Oct 7, 2017 at 20:33
  • I ended up nailing a couple 2x4's to the bottom of the floor joists to keep them from twisting and then I cut up and pried out the rim joist and replaced it with a single treated 2x10. Nothing seemed to shift. Thanks for your answer!
    – Jon
    Oct 9, 2017 at 14:07
  • 1
    A few additional notes that may help someone in the future. After nailing 3/4 of the new rim joist, I noticed that the green treat board I used was twisted and warped. I ended up using long lag bolts with washers to get the board to sit tight and flush. I pre drilled the holes for the bolts and I used a bigger spade bit bit to countersink the head of the bolt and the washer.
    – Jon
    Feb 22, 2018 at 16:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.