Ciscoecuk,
No you do not cut the original rafters, as Mike G says, you put a lay board on top of them, then sit the jack rafters on the lay boards, and then the valley boards on top.
Regarding fibre glass valleys, I have been talking to two different roofers this morning, and both say that you can get away with a slight variation in pitches but not too much. Both much prefer lead, the beauty being it fits any shape. Being relatively short valleys you don't need that much.
Dennis
No you do not cut the original rafters, as Mike G says, you put a lay board on top of them, then sit the jack rafters on the lay boards, and then the valley boards on top.
Regarding fibre glass valleys, I have been talking to two different roofers this morning, and both say that you can get away with a slight variation in pitches but not too much. Both much prefer lead, the beauty being it fits any shape. Being relatively short valleys you don't need that much.
Dennis