Working out rise?? Please help??

[rf]

Hi all, Taking a test were i have to build a small pitched roof with gable end and hip end. Span is 1076mm @ 30 degree pitch. Can anyone tell me what they make the rise? Ive got 310mm??

Also for the hips how can i work out how much to lower the hip to line up with the other common rafters without affecting the seat and plumb cuts??

Any tips as to marking out etc would much appreciated.

 

[noseall]

tangent 30 (degrees) multiplied by 538 (half the span) =310.

 

[noseall]

Also for the hips how can i work out how much to lower the hip to line up with the other common rafters without affecting the seat and plumb cuts??

You can lower the hip rafter (wholesale) by removing material from the seat cut, but don't touch the plumb cut if the hip blade is sitting at the correct angle.

An important measurement (bible, God) is the measurement from the peak of the rafter (the furthest point up the ridge) to the peak of the birdsmouth (the outer point of the wall plate where the seat and plumb cut join).

 

[rf]

Thanks Noseall much appreciated