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Originally Posted by Borske
Thankyou for your responses.
Can you tell me how you both figured that the rise is 4.5? What formula did you use to find this.
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Theres are many ways to figure this dpending how good you are with math and what your comfortable with.
One way is like this;
rise/run x 12 = (pitch)
Your example with a 6' rise and 16' run.
6/16 = .375 x 12 = 4.5
That will get you close to what you want but that will not be your pitch because your 6' is to the top of the rafter at the ridge line and that doesn't account for the rafter thickness and the H.A.P. cut (height above plate) which is the plumbcut line measured on the outside of the top plate vertical to the top of the rafter after you cut your birdsmouth. Once you cut the level seatcut out you measure this. This means that your pitch will be lower than 4.5/12.
That 4.5/12 is with a perfect triangle with a 6' rise and 16' run giving you a 17' 1-1/16" diagonal. You will have a different pitch and measurement with whatever rafter stock you use.
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