Dry rot / wet rot in wooden ceiling joists

Ared

Reading this I also have a similar issue with wet rot in my window area on the first floor, I own the joists but the tenant below is being very difficult and making it very hard for me to gain access to the flat below to cushion the ceiling whilst we do works. I have since withdrawn my offer to cushion the below ceiling. Leaving me no option but to request they support the ceiling themselves when we do the work from above! Does any one have any advise on this for me !