On 21/06/2019 19:47, Al wrote:
Hi all,

Just about to get the house re-roofed and have noticed that at the
extremities there are a handful of rafters which have developed some form
of rot due to the incursion of rainwater. No evidence of woodworm AFAICT.
So the lowest 10-14" of the affected rafters really need attention before
the new roof goes on.
Is there some way of replacing *just* the rotten bits? We're only talking
of the most outside rafters closest to the exterior walls at the point
where they meet the guttering line.
How to proceed, please.....?

In your situation, it would be quicker and cheaper to replace the rafter.

Once the tiles have been taken off, the battens and felt, the rafters
would be exposed.