Increasing rafter pitch on lean to extension

[jackofairbrother]

Hi,

Probably be a quick yes or no!
Looking to try and maximise roof pitch, have a lean to extension going in under current windows. So height of ledger plate is already set.
We have a bi fold door going in with a catnic cavity lintel above. To match existing I’m going to finish with headers and do without the soffit/eaves.
From what I understand you need at least 150mm of masonry on the inside skin of the steel.
Just wondering if it’s possible where the rafters would bare down on the wall plate above this can the rafters on the birdsmouth be cut straight up on the heel and fixed with something like the Simpson strong tie on the seat cut, therefore increasing pitch without having to put a standard block then wall plate for the steel to not get in the way of the birds mouth?

Thank you!

 

[jackofairbrother]

Sorry, any chippys our there got any idea ?

 

[23vc]

Are you talking about doing away with the wall plate, or the block underneath it? Quick sketch will help

 

[jackofairbrother]

Keeping the block and wall plate as I believe that’s needed.
I’ve added a couple of sketches (If you can make it out lol) both side on, first one I believe is the normally way to do it, second is with a block cut down to 150mm but only having the seat cut.
Basically trying to gain a couple of degrees in pitch to get to 15 for a standard velux.
Bit similar to the last image?
Thanks!

 

[^woody^]

Why can't you raise the rafters at the other end?

 

[domdee]

Why can't you raise the rafters at the other end?

Windows. Although he could go above either side of the windows and have a lead flashing stepping down to form a flat slope to joint the roof further down

 

[domdee]

poor picture shows how a better pitch can be achieved.

 

[domdee]

similar principal

 

[^woody^]

If that is the case, then why **** up the internal appearance, the view for 99.9% of the time when there is a much simpler option?

 

[jackofairbrother]

Cheers. Will have a little look in to what the inside will be like.

What’s the simpler option?

 

[^woody^]

Raise the other end

 

[jackofairbrother]

Suppose so, just don’t think it’ll look right.
So birdsmouth is the only way to finish it on the wall plate?
I take it the windows will need to be removed for the lead flashing to go down the sides and under neath with raising the pitch higher?