Easiest method for cutting rafter angle

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  #1  
Old 06-15-19, 04:02 PM
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Easiest method for cutting rafter angle

I have to repair a rafter in my attic. What is the easiest method for cutting the proper angle that butts against the ridge?
 
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Old 06-15-19, 04:57 PM
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What is bad on the old one?
Will you be removing the old one, if so it could be your pattern.
You mentioned ridge so we can assume it is not a truss??

And as always, pictures help.

Bud
 
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Old 06-15-19, 05:16 PM
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I dont have photo handy but the old rafter is split... the worst of it at the ridge beam.

i was going to scab another board to it but i am not sure how to cut the angle.

 
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Old 06-15-19, 05:23 PM
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You can use a piece of paper or cardboard and cut it to match that angle. If the rest of the rafter is good just double up the top plus some past the break.

Is the roof still in place? If so, be sure to push the new board up a bit higher so when you release it comes back to where you want it.

Bud
 
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Old 06-15-19, 06:09 PM
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Thanks for taking the time to reply Bud. A template is a great idea but i am having trouble comprehending how to do it.

i only need to figure out the cut at the top, im going to use a shorter piece that wont span the entire length to the wall. I figure once i have the correct cut it will attach to the beam as well... maybe with a bracket?
 
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Old 06-15-19, 08:18 PM
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Get up to the top of the rafter where it attaches to the ridge and cut or fold a piece of paper until it matches the bad one or one of the others. Once it matches you have it. No calculations and if it takes a few tries not a problem.

Bud
 
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Old 06-16-19, 02:37 AM
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I have one of these and they work well to give you the angle.
https://www.harborfreight.com/multi-square-1701.html
 
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Old 06-16-19, 04:47 AM
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If you like new tools, a Starrett 505 protractor is something that would work for this and multiple future projects. But if you want to save a trip to town, I've done as Bud suggested for years and it works fine. Rafter angles are almost always a ratio of Y inches of rise to X inches of run, and seldom come out to an exact number of degrees anyway, so you don't care how many degrees it is as much as you want to draw the cut line at the right angle on the piece you're working on, so the folded piece of paper is perfect. If you want to do it true "old school", you don't even need to crawl back up in the attic. Climb up to the edge of the roof with a level and tape measure, see how many inches of rise you have per foot of run, and then you can use your framing square to set your angle.
 
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Old 06-16-19, 05:41 AM
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I learned to cut rafters the old school way.... from an old timer.

I use a framing square to mark my cuts.
If I need a 4/12 roof pitch for example, I put the short end of the square at the end of the board & put the 4" mark on the bottom corner at the end of the board. Then adjust the square so that the 12" mark on the long side of the square is on the bottom side of the board. Then just make a mark with a pencil along the outside edge of the short side of the square. That cut will fit the ridge board.
Then do the same thing in reverse for the other end of the board for the fascia & where the rafter sits on the top of the top plate.
Just for clarification, The short side of the square will be the cut at the end of the board for the fascia. The long cut will be where the rafter sits on the top plate.

Its been 20 years since I have done this & I haven't had the opportunity to do it often so I could be off a bit on my instructions. I can do it physically, but I don't know if I can tell you how to do it accurately. If anyone see's an issue with my instructions, please feel free to correct.

I'd be willing to bet there is a video on YouTube somewhere to show you how to do this but you need to know the pitch of the roof so you can make the correct cuts.

OR, you can just use the "bend/mark the paper" advice given above by other members.... simpler & easier.
 
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Old 06-16-19, 03:56 PM
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There are apps for your phone that will show the angle. Search for "level".
 
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