Rotten joist ends - solutions without affecting below ceiling?

[aks7]

Hi - newbie here - first post so please bear with me

Doing a renovation on my apt and have lifted all floorboards as levels are all over, I've discovered that a few of my joist ends are rotten - pic attached. I believe this was due to a historic leak but the water ingress has been stopped.

I'd like to repair ideally without affecting the ceiling of the downstairs apartment - what are my options?

I wanted to sister all the joists (as a way to level them), and have seen I could do this to strengthen the rotten joists, but I'm not sure (1) how I'd cut the rotten sections away above without being able to support from underneath? and (2) I also have herringbone struts which prevents me from sistering end to end - are these removable / should I replace with noggins?

Would love some advice, Cheers

 

[Why Not Indeed]

I would check what your lease says about how much of this structure you can work on without interacting with the freeholder.

I'd like to repair

To be clear, other than looking a bit tired, do you actually have a problem here? Ie, is the floor bouncing when you walk in the area, large cracks in the ceiling below, etc? If the answer to that is "no" then I would leave this can of worms closed, IIWY.

 

[stevie888]

To me that looks like dry rot which will not stop just because the leak has. You need to get this confirmed and you need to talk to the freeholder becasue I don't think it can be addresssed purely from above

I finished relaying a bedroom floor in our recently reposssed rental place only yesterday where 3 joists had (dry) rotted clear through. I have stripped the floor, dropped the ceiling (lath & plaster) and cut back a couple of feet beyond any indication of rot on the affected joists. I opted to add a trimmer between the first clear joists, (which I then sistered) and support existing and new infill joists off that trimmer.

Probably it woiuld have been better to replace the lot but I settled for several sprayings of chemical treatment including onto the walls where spores can lurk