Ceiling Joist Repair, rotten wood

[Rowan11]

I am renovating a rental property. In the bathroom we have found severe wood rot in 1 of the 3 main ceiling joists. The rot goes through 2/3 of the joist (4 2x10 with 1x6 on each side) on the right side of the joist, approximately where the rot ends is the bathrooms vent pipe which is what makes this hard for me. Should I cut the rot straight out, replace the wood and sister on each side? Is that enough support?

We have discussed interlocking the new wood with the old, bolting the wood, and adding a 4x4 post on each side of the vent pipe.

Any input would be appreciated.

 

[ladylola]

I'd always be inclined to take out any rotten timber and generally some of the adjoining timbers as there may be unseen infection. For example we normally cut out something like a metre (just over 3 feet) past any rot.
Wheather to replace the entire joist or to repair with a bolted on section can be as simple as looking at what work is involved, it will probably be easier to replace unless this would involve tearing down undamaged sections of the building.
Don't forget to identify what is causeing the rot (probably moisture) and take measures to prevent it.
If you can could you post some pictures of your problem as this will help us to advise you much easier.

 

[Rowan11]

There is about a metre of rot and mold. The rot is quite extensive as I can pull large chunks of the joist with my hand. There is a wall sitting almost directly beneath the joist, however it is not load bearing. Only 1/3 of the joist sits on the underlying wall which has lead me to the doubts. What is the best way to insure proper weight distribution when repairing the joist? I am thinking of a lap joint with glue, deck screws, and toggle bolts. Would this be sufficient or do I need to add support via a beam on each end of the repaired joist? As for the moisture we have pinpointed it to a leak in vent boot on the roof.

I will post pictures this evening as I am looking to solve this issue in the morning.

 

[chippy5]

bite the bullet replace the whole joist then you know its stable. could be quicker than trying to cut a joint in situ. is the renovation covered by building regs? if so they would probably want a new joist

 

[RonnyRaygun]

Is it wet rot or dry rot? Dry rot is much more of a problem and you need to be very careful to fully eradicate it.