Compound rafter cut

[new land owner]

In the spring I intend to add a porch to the front of my cabin.  It will look like this:


My question is what would be the compound cut on the part of the rafter that is attached to the roof line?

I know the top of the rafter wil be just short of 34 degrees but I don't know if there is an each way to figure the compound cut on the bottom.

By the way both the porch and the camp roofs are 8/12 pitch.

[UK4X4]

You have done the dwg in Google sketchup ?

use the model you have done and actually put in the wood underneath the roof

That will give you the angle as you can measure it

However the real world differs from theoretical - so you'll really need to measure on site and make it fit !

[Don_P]

If the porch is also an 8/12 the angle will be the compliment of 34 degrees... 56* angle. The bevel will rest against the roof's 34* pitch so it will be 34*. Run sleepers on the roof to rest the porch rafters on fully supporting the compound seat cut.

[PEG688]

Over frame the gable like this,

[new land owner]

Thanks for the pictures that is just the way I am going to do my porch roof!

[new land owner]

If the porch is also an 8/12 the angle will be the compliment of 34 degrees... 56* angle. The bevel will rest against the roof's 34* pitch so it will be 34*. Run sleepers on the roof to rest the porch rafters on fully supporting the compound seat cut.

Don

    How do you cut a 56 Degree andle on a chop saw that only goes to 45 Degrees?

Tom

[Don_P]

I use a skill saw for almost all framing, it's easier to move the saw to the work than to move a large piece of lumber to the saw. But, if you need an angle beyond what the chopsaw can cut you can make a triangular plywood block with say a 11 degree angle that the board rests against and add that to the 45 degree saw setting. The length of this cut is going to be beyond what most chop saws can cut. If you use your framing square to lay this out the 8 side will be the top, plumb cut and the 12 side will be the compliment or level angle. hint: the square is 16" on the tongue and 24" on the blade, double 8/12 and you have 16/24, using the full square allows you to easily layout the long line needed for this cut.

[new land owner]

Don

   I was looking at my Swanson speed square and I noticed there is a 55 degree mark on it.  I was thinking I could cut a "template" on a 1 x 6 and use this to mark the 55 degree angle on my roof joists?  I then would set my skill saw for 34 degrees to cut the correct compond cut?

Tom

[Don_P]

Sure that'll work. I like a 12" speedy for rafters and bigger stuff. If you'd like to check the angles cut it a bit long and slide it parallel and downhill from layout, check it, then cut it down to proper layout length. Start with your longest pieces and work your way down so that if you blow one it can be cut down and used for the next shorter jack.

[new land owner]

Thanks again.