On Friday, 21 September 2018 13:11:11 UTC+1, Dave Liquorice wrote:

That's all good stuff on the face of it. you say he's a local bloke,
does he have good reputation in the area, guess he does or you
wouldn't have used him in the first place.

Yes; very good reputation.

Presumably rest of the works are good and you'd have signed it off
quite happy and satisfied if the fall had been correct?

Yes, very pleased with the rest of it. I feel sorry for the builder as he is very competent - indeed his workmanship has really impressed me elsewhere - but even competent people can make mistakes.

If there are places that retain water I think the strip and replace
is the better option and I suspect your builder would agree.

It is difficult to define 'retain' as even with a proper fall some parts of the roof will remain wet for a period after rain and it can be difficult to tell the difference between wet and pooling.

As you have highlighted, there are complications with any of the proposed fixes but I think I'll be opting for the strip and rebuild. That can hopefully be done such that this whole issue will eventually become a distant memory.