I think a 1/3 pitch is really a 4/12.

Given that, using the same equation I get a hypotenuse of ~12.65

12.65 X 12' of run = 151.8" for rafter length. (But it's been awhile. I'm not a math whiz...)

How we doing Northern Hewer?

Don Perkins
Member, TFG

to know the trees...