Minimum width of valley on roof junction

[RichA]

I am looking to do a rear extension and for planning reasons can't go full width, so need to inset very slightly. What is the minimum that the inset can be from a practicality of building the roof/join standpoint. i.e. I believe I will need to fit a ridge and a valley (see attached).

Would a 215mm inset be possible? Less?

Ideally I would achieve this with a reduced soffit rather than insetting the walls?

 

[garyo]

My neighbour has practically zero which means it's all lead and pointing at the eave/verge. It looks like a mess, but it's clearly possible.

 

[^woody^]

What we have done previously with these, is instead of having the tiles in that narrow section between the hip and the valley horizontal as normal and lots of cuts and small peices, fit them parallel to the hip and valley do that there are no cuts. You hardly notice and it looks much better beng nice and straight up the valley.

But you could, with a bit of work, devise something where the valley starts at the edge of the hip tile. It wont look nice as the depth of the valley is enhanced, making it look odd up against the hip tile

The hip will be mechanically fixed in any case, so no problems with that, and it would probablly need to be done in lead instead of a fibreglass trough.

 

[RichA]

Thanks. Looks like I may get away with just insetting the roof (with smaller soffits).