5 Year Old Floor Joist Repair

[Wesley Belk]

About 5 or 6 years ago my dad and I repaired the floor in the bathroom (8 feet x 5 feet) of my master bedroom. There was a leak in a stand up shower that the previous owner did not have repaired. The leak caused the subfloor to rot (area about 4x4 feet) and the top 2 to 3 inches of the floor joists to rot (the affected areas ranged from 4 to 5 feet long). The original floor joists are 2”x10” and about 12 feet long. We tore out the subfloor and exposed the floor joists. The water damage weakened the floor joists enough to allow the floor to sag about 1” to 1 ½”. We used two floor jacks sitting on 4” thick 8”x16” solid concrete blocks and a 4”x6” by 6 feet long treated beam on top of the floor jacks to raise the floor back into position. After we jacked the floor back into position we sisterred 2”x8” boards to the side of the original floor joists to provide a good nailing surface since the top 2 to 3 inches of the original floor joists had rotted away. We extended the new boards about 2 or 3 feet beyond the rotted area. We left the floor jacks in place and they are still there. After we finished we installed a new subfloor and then tile and redid all the bathroom fixtures. I have been reading posts on the internet about the proper way to replace or sister joists and I am now concerned that we may not have done the job correctly.

The things I am concerned about are:

The leak that caused the damage was stopped, but will the rot on the original floor joists spread to the new boards that we sisterred on to them (the boards that we sistered on were not treated)?

Should I treat the rotted floor joists in some way? If so, I can only easily get to one side, since the other side is covered by the board we sisterred on. I read about some epoxies.

I would like to be able to remove the floor jacks and have the floor joists support themselves. Can I do this by sintering on another full length treated board on the other side (opposite side from where the original board was sisterred onto) of the original floor joist?

Is there away to replace floor joists without removing the sub flooring and still being able to secure the subflooring to the new joists? Like I mentioned we redid the bathroom and I would like to avoid having to do that all over again if at all possible.

Thank you for your help.

[Matt Fellman]

Short answer is you have a mess on your hands and if you want it done right you will have to tear it apart and start over.

If that's not done you can do more "band-aid" work and it may or may not work. In reality, there are probably millions of bathrooms in the country in way worse shape that still "work" from day to day.

Yes, the rot may spread. I doubt any surface treatments will do much good due to a lack of access to much of the rot. Really, I don't know a whole lot about them since any rot repair I've ever done has involved just removing the damage.

The one thing I'm really puzzled about is why in the world you wouldn't remove the jacks before setting the new floor and fixtures? At this point I'd leave the jack or trade it for a post if you need the jack for something else. You can try to remove it but some deflection is likely which could damage the floor covering, cause plumbing to move and leak, etc.