artistall Posts: 88, Reputation: 5 Junior Member #1 Jul 26, 2005, 12:49 PM
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!
 atremo Posts: 1, Reputation: 1 New Member #2 Oct 20, 2005, 03:05 PM
Question
 labman Posts: 10,580, Reputation: 551 Uber Member #3 Oct 20, 2005, 04:17 PM
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.
 Dennis Lutz Posts: 1, Reputation: 1 New Member #4 Mar 21, 2007, 08:10 AM
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
 acurren Posts: 5, Reputation: 1 New Member #5 Aug 29, 2009, 05:41 PM
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!
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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