“ The secant” or line length ratio. That is achieved by dividing the hypotenuse of the unit rises and unit run of the pitch (9/12) by 12 inches. So in this case, 15 inches divided by 12 equals 1-1/4. 1-1/4 x16” equals 20”. 20 is the common difference of the jacks.

The engineer’s prerogative.

That’s a term allegedly made up by Will Holladay. It is a ‘bastard’ to frame, was the answer.

That’s a good question. I’m gonna try to figure that one out.

@@roofcuttingandstacking7925 i think if you have it set as an education channel that effects it

Yeah

Sometimes by hand sometimes on CAD.

@@roofcuttingandstacking7925 when doing them by hand you use a protractor for the angles?

I use the ratio of the sides instead.

If you ever get to California, I give all day roof framing classes in my shop in Berkeley.

@@roofcuttingandstacking7925 sounds good I work and live in central Arizona, so it’s not that far away. Have a great day

Right on man. If you ever get to Berkeley, California, I give 8 hour long roof framing classes in my shop. We build 16x12’ models that are pretty cut up. .

Generally, the first Jack dimension will be less than the common difference, because there is a deduction on the first one from centerline to side of hip or valley. The rest of the jacks don’t get the deduction.

Because we want to get to the point on the outside of the boards where the king common rafter meets the hip rafter(lead edge). That is the point where the step-down math begins. From there the common difference is marked along the spine of the common rafter from the top down. Once completed, we measure up from the heal stand line to the marks to obtain the consecutive jack rafter lengths.

Email me at [email protected]

Is this a standard hip roof, not a irregular? If so your offset will be the same as the additional 6”. Your plate will raise on the side where the difference is unless the rafter depths are different.

@@roofcuttingandstacking7925 great thanks for replying

Dont know.

@@roofcuttingandstacking7925 You might want to have someone look into for you but it's the size of your phone

I shoot all the videos with the phone. When I start doing longer more professional videos, I’ll upgrade.

There are a few videos about that as well.

Go to roofframingtools.com and sign up. I have a class on April 30th at my shop in Berkeley. It is 8 hours long. We build a 7’x15’ cut up model like you see on youtube. The cost is $320. We go from 8-4:30 with a lunch at 12.

Technically called the secant of the common rafter. The secant is obtained by using the square root method of the unit rises to determine the hypotenuse, then dividing it by 12. So if it was a 6/12 pitch it would be: 6 squared plus 12 squared equal, then push the square root button and divide the answer by 12 to put it in inches. That would look like 36+ 144= 180, the square root of which is 13.416. Divided by 12=1,118

@@roofcuttingandstacking7925 what's a secant? Also what about the 16 you were saying? Also wouldn't that be for a 12 inch run bigger the run bigger the number? So you devide your total rafter length by 12? Is that with or without the ridge dediluction?

I go over a whole bunch of that stuff on this channel. But essentially you take the secant and multiply it by the on center spacing to get the common difference of the Jack rafters.

@@roofcuttingandstacking7925 what's a secant

Its in the comments above.

Tower roof in San Francisco.

I cut roofs for them as a sub contractor.

Thanks bud. I wish I were in the Bahamas!!

I remember him. Very cool. Thank you.

Technically, it is 30°. But why I said it is because traditionally a lot of guys would back the hip/valley the same as the angle of the hip/ valley in elevation. That really is only effective under about an 812 though. There’s about four other methods, but I find that the fastest is just to use a scrap of wood and use the rise run ratio to calculate the angle on the Skil saw.

Assuming the ridge heights were the same, yes they would. That is assuming I understand your question. I give eight hour Roof Framing Class is in Berkeley California if you are interested.

@@roofcuttingandstacking7925 thanks for responding. I wish I could attend your classes but I live in Alabama. I’m not gonna ask a million questions because I know it can be hard to answer through text but on your video “more bastard hip and valleys” are the lengths of you hip and valley rafters the same from the ridge to the building line of your little model. It’s hard to tell. That’s my last question and thanks for your time and help.

@@chiller19100 No because with varying plate heights the hip has to slide inboard which changes the span. I don’t mind questions at all. It’s good to find where I’m being vague so that I can shoot another video

@@roofcuttingandstacking7925 I understand thank you. So the plumb cut angle would also be different on the valley rafter?

@@chiller19100 It’s important to remember that there is a static angle when any two pitches converge. That means both the top and the bottom of the hip and valley move location together relative to the overhangs. This being the case, the angles in plan view of the hip and valley are consistent. That includes all of the cuts.

Yes, there are steel bents connected with 4x ridges.