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# Fascia board cut for hip on gambrel roof

#1
07-08-14, 12:06 PM
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Join Date: Jun 2014
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Fascia board cut for hip on gambrel roof

I am going to box in the barn I am building and need to put up a fascia board. How do I figure out the correct angle for the hip cut? Here is a diagram..the top portion is a 3/12 and the bottom is an odd size at 11.26/12. Thanks

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#2
07-08-14, 01:00 PM
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Same angle as the rafters or trusses. If they're not cut that way, grab two pieces of 1x or whatever you have, as long as they're the same width, hold one along the lower roof, tight to the intersection, and the other on the upper roof, tight to the intersection, so they overlap. Make a mark on the inside corner of the lap, and the angle that you want will be from that mark to the outside corner of that piece.

#3
07-08-14, 01:03 PM
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Well, I'm no expert, and I'm sure there is a simple way w/o calculations....but using math it appears the angle at the meeting point is 122.78 so 61.39 would be half of that. So it seems like you would cut 28.61 degrees which would leave the other side of the cut 61.39.

Without a saw set up and scrap to test on, I'm not positive though.

Like I said, there's probably a much easier way using a square and a pencil.

Where's a real carpenter when you need him???

#4
07-08-14, 01:18 PM
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Join Date: Jun 2014
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Both angles need to be same so the top and bottom of the fascia boards line up...If the angle is a 123* ..maybe, like you said, 123/2 would be correct.... maybe I will get some scaffolding and try the cut and try method

#5
07-08-14, 02:28 PM
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The method I described is relatively common among carpenters, and easy enough to show, but not so easy to put into words. So, if that doesn't work, and you're going to go with trial and error, just fold a piece of paper to about what you think the angle should be, hold it against one roof, mark the center with a pencil, flip the paper so that it is against the other roof, see how the paper and pencil mark compare, then refold the paper accordingly. Or, if you happen to have one, a bevel would do the job. Point being that, as you said, both angles are the same, so you just need a pattern to cut the boards at, and the number of degrees is irrelevant.

#6
07-08-14, 02:30 PM
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Oh, now that I see what Pedro wrote, I think thats exactly right. If you mark where the boards cross at top and bottom, No matter what angle the roof actually is or what size boards you use (as long as they are the same) by marking top and bottom you should bisect the angle and the boards will have to match. Then just transfer to the fascia you are going to use.

#7
07-08-14, 07:19 PM
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If the pitches you have listed are correct.... and i haven't made an error...

Your miter should be 14.571 degrees on each side of that joint.

Picture the angle as 2 isosceles triangles on either side of a rectangle.

The angle opposite 3 in a 3:12 pitch is 14.036.

The angle opposite 12 in a 11.26:12 pitch is 46.822.

They are separated by a 90 degree angle. So take 90+46.822+14.036= 150.858. 180-150.858= 29.142. 29.142/2= 14.571

But yeah, a sliding t-bevel along with some scraps to make some test pieces would be easier. lol