On Feb 29, 7:04*pm, marson wrote:
On Feb 29, 8:52 pm, "Pat" wrote:





wrote in message

...

On Feb 29, 8:35 pm, "Pat" wrote:
wrote in message

....

I have a 3/12 pitch roof (3 inch's of rise for each 12 inch's of
run). *I am installing Facia Board (1x8 pine) and my question concerns
the proper angle cut at the ridge of the roof. *The right angle
triangle by definition of the 3/12 pitch has a 90degree angle at the
top plate center, a 14degree angle at the eave and a 76degree angle at
the ridge (for a total of 180degrees in the right triangle)

Vision a gable roof and the two right triangles would fit against each
other and form the gable. *The two 76degree angles would be together
at the ridge of the roof. *What would the plumb cut be in degrees for
the facia board on the ridge? *I thought that with two 76degree angles
combined that I would split that in half for the cut, but obviously
that is wrong. *The angle cut is not 76degrees and my miter saw
wouldn't cut that anyway. *I think the angle cut may be 14degrees for
each of the facia boards joining at the ridge on the two 76degree
angles, but I don't know why I think that or how the angle is actually
calculated.

Thanks for any assistance with the angle cut.

David

90 minus 76 *= 14

14degrees makes sense, but why am I subtracting from 90degress when
the angle is 76 degrees? *Guess I should have paid more attention in
school huh?

Probably need a blackboard so I can draw you a picture. *A miter saw makes a
90 degree angle with the fence. *To cut a 76 degree angle on the board you
set the saw to 14 degrees.

What most carpenters would do is hold their speed squares on the 3/12
mark, and look down and see what angle the plumb cut corresponds to.
Mathematically orientated carpenters can use a scientific calculator
and enter 3 / 12 INV TAN. * Which I guess is technically the angle of
the rafter to the ceiling joist, but it is also the angle that you set
your miter saw to. *Like Pat said.- Hide quoted text -

- Show quoted text -

Or use a bevel gauge to set the saw to. That's what I do and it
avoids the problem of odd angles. Been a long time since I actually
read degrees of angle on anything.

Harry K