cutting rafter help
#6
  
I'm making a lean to greenhouse. The highest wall is 97 1/8" high. The outside wall (low eve) is 84" high. Adjusted run is 98". I want my pitch at 2:12 but I can't get the speed square to pivot to 2" on a 2x4 rafter. Giving the height of the 2 walls, what should the pitch be? And if I can keep the 2' pitch, what would be the angle of the plumb cut? 

I bought a construction calculator because the math involved was making my head spin.

Jim
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#7
  Re: cutting rafter help by Halfathumb (I'm making a lean to...)
If one wall is 8' high (or close) and the other wall is 7' high, and there's 8' (or close) in between them, then the pitch is going to be 1 1/2:12.

I came up with 7 degrees for the plumb cut (or 83 degrees, depending on what you measure from).
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#8
  Re: RE: cutting rafter help by DieselDennis (If one wall is 8' hi...)
(05-22-2020, 01:09 PM)DieselDennis Wrote: If one wall is 8' high (or close) and the other wall is  7' high, and there's 8' (or close) in between them, then the pitch is going to be 1 1/2:12.  

I came up with 7 degrees for the plumb cut (or 83 degrees, depending on what you measure from).
Thank you sir. I also came up with 1 1/2:12 pitch but rounded up to 2 thinking it would simplify things. 

Jim
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#9
  Re: cutting rafter help by Halfathumb (I'm making a lean to...)
Yeah, your back wall should be 100 5/16" for a 2:12.  Plumb cut is 9.46*
"This is our chance, this our lives, this is our planet we're standing on. Use your choice, use your voice, you can save our tomorrows now." - eV
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#10
  Re: cutting rafter help by Halfathumb (I'm making a lean to...)
https://www.blocklayer.com/roof/raftereng.aspx
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