Water damaged joists

Doing some prep work on a bathroom reno, notice that some the joists around the shower are water damaged/rotten. Seems to only be the first couple centimeters.
What's the best option to fix these ?
Would a chemical treatment be enough or should we cut the rotten section out and replace with some new timber ?

Thanks

Nic

If you've solved your moisture problems and the timber can dry out, the fungus will become dormant and not spread any further. You could treat them with CN timber emulsion or another treatment for peace of mind.

Cheers
Michael