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-   -   Seat Cut Rafters (https://www.askmehelpdesk.com/showthread.php?t=11314)

  • Jul 26, 2005, 12:49 PM
    artistall
    Seat Cut Rafters
    I'm building a garage and want to use 2 x 6 rafters gable roof. How do I figure the length of the rafters and the angle of the plum and seat cut? I'm just pouring the slab. Then I'll build the walls and then the rafters, decking and composition roof.
    The span will be 20 feet and the rise I guess around four feet.
    I know I'm on the right track but can't remember how it goes
    Oh and a one foot overhang!
    and maybe an ingrown toenail!
    lol
    Thanks!
  • Oct 20, 2005, 03:05 PM
    atremo
    Question
    Did you ever get your answer
  • Oct 20, 2005, 04:17 PM
    labman
    If he did, no thanks to me. I must have missed it. If anybody else happens by: Many of your squares have tables on them to figure that, or you could use basic geometry. Easiest thing might be to use a chalk line and lay it out on the floor, and measure.

    Usually I let questions over a week old go, but since you asked, I answered.
  • Mar 21, 2007, 08:10 AM
    Dennis Lutz
    Quote:

    Originally Posted by artistall
    I'm building a garage and want to use 2 x 6 rafters gable roof. How do I figure the length of the rafters and the angle of the plum and seat cut? I'm just pouring the slab. Then I'll build the walls and then the rafters, decking and composition roof.
    The span will be 20 feet and the rise I guess around four feet.
    I know I'm on the right track but can't remember how it goes
    Oh and a one foot overhang!
    and maybe an ingrown toenail!
    lol
    Thanks!

    Dennis Lutz
  • Aug 29, 2009, 05:41 PM
    acurren
    Quote:

    Originally Posted by artistall View Post
    I'm building a garage and want to use 2 x 6 rafters gable roof. How do I figure the length of the rafters and the angle of the plum and seat cut? I'm just pouring the slab. Then I'll build the walls and then the rafters, decking and composition roof.
    The span will be 20 feet and the rise I guess around four feet.
    I know I'm on the right track but can't remember how it goes
    Oh and a one foot overhang!
    and maybe an ingrown toenail!
    lol
    Thanks!

    To make the cuts use a simple speed square and mark the board on a 4 common for the top cut. For the seat cut mark the top cut then put the base of the square along your mark so you can mark a 90 degree line for the cut to sit on the wall.

    You should be shooting for a 5/12 pitch. To find the length of any rafter use a framing square, that's the big one, and find the LENGTH COMMON RAFTER PER FOOT RUN scale on one side. Follow the column down the square until you find your desired roof pitch. It will give you the multiplier.

    Example: 20' span half that, 10' run, 5/12 pitch, multiplier is 13. So it's 10X13=130 inches for the common rafter. Convert to feet and inches= 10' 10" If you use a ridge allow for it in your run measurement etc...


    If you need more help contact me through my website contact form at BUILDINGS OKLAHOMA

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