Recently noticed whilst tidying up the loft that I have a rafter which is rotten about 3ft up from the bottom (screwdriver goes in about halfway in a 3x2) I can see there is a hole in the felt right above where the damp patch has formed. It is the rafter nearest the wall and rafters are about 15 inches apart so I don't imagine there is much load on it but nevertheless I would like to get it sorted since it will only get worse. I am planning to get a roofer in to look at the the leak but as regards the rafter it doesn't look to difficult a job to sister a new piece of timber and cut out the rotten piece, Would that sound feasible for a "competent" DIYer?