How to calculate hip backing angles

Here’s one way to calculate hip backing angles. Backing your hips makes everything so much more clean and accurate. Highly recommend! There is also a geometric way to determine these numbers, but once you fingers out this method it’s really fast and easy. Let me know if you have questions.

[@pdcro1247]

Well done
That calculator is probably the most powerful tool on any job site

[@luisbibiano7237]

Clean work

[@user-uq8hf5eh3u]

would love to see you do video on split pitch hip!!

[@leoalbini797]

Great video! Now, for an irregular hip roof, do I follow the same steps for each pitch? For example, a 6/12 and 12/12 roof, do I go 6 hip and 12 hip or it changes?

[@anthonyz7327]

Excellent video

[@Quietvibes07]

So for a sleeper bevel on an overlay you would add the two backing angles and subtract from 90 correct?

[@luisbibiano7237]

Wow 😳

[@salg-1980]

Is it the same with curved rafters?

[@wendimccain8580]

Amazing brother! Where are you located? Skip McCain

[@Redoakcarpentry]

Thank you skip, I’m in Michigan

[@wendimccain8580]

@@Redoakcarpentry Really. I'm in Mt. Clemens, MI. Skip McCain

[@damonisrael7884]

Michigan as well

[@salg-1980]

I need your advice. I’m building myself a shed with a hip roof and a slight curve. I will use shingles but I’m wondering how can I make the exaggerated ridge cap while still keeping the roof waterproof? I know you’re a framer and not a roofer but maybe you can help.

[@Redoakcarpentry]

Sure as long as it’s a not super tight curve, more gradual would be easier. And make sure it’s warm, so the shingles have some bend. I think your biggest issue will be cracking the cap when you try to conform them. Put on a good water proof underlayment and it won’t matter what your shingles do.

[@salg-1980]

@@Redoakcarpentry - One more question. When framing a roof, when using 2x6 and 2x8 if one is Doug Fir and the other is Redwood because there is no 2x6 redwood, does that make a big difference if both are kiln dried and construction common?

[@Redoakcarpentry]

@@salg-1980 the only difference between materials is their strength. Certain species of wood can carry more load, so long as you check the span charts for that particular size and species, and make sure they correct, you should be good. No offense intended, you strike me as rather inexperienced, have you ever built a hip roof?

[@salg-1980]

@@Redoakcarpentry - I’ve never built a hip roof. The angles, birds mouth isn’t really a problem, I understand that. I’m making a shed, 8.5 x 15 on slab foundation. I plan on using 2x8 on the top ridge and hips and 2x6 on the common. I also plan on adding 2x6 collar ties to the bottom of the common rafters and also the top of the common rafters right below the ridge. It’s the materials I want to get right. The roof will have shingles.

[@Redoakcarpentry]

@@salg-1980 right on! Let me know how it goes!

[@salg-1980]

How do you do this with a curved rafter?

[@Redoakcarpentry]

It’s takes a lot of geometric development and you have to hand cut it.

[@Redoakcarpentry]

To my knowledge, this has never been addressed in any reference text or video. I have worked it out, but it is a ridiculous amount of drawing.

[@salg-1980]

@@Redoakcarpentry - 🙁 I had a feeling it was going to be difficult.

[@Redoakcarpentry]

@@salg-1980 backing angles aren’t necessary if you understand roof geometry and you’re using conventional lumber. They make hip/ valley connections easier in many respects, but in the case of sloped hips they complicate it tremendously. Backing angles are specific to the pitches involved. If you took a curved hip and segmented it into 10 smaller straight lines, you’d essentially have 10 different pitches, each with a different backing angle. What that looks like on an analog curve is a rolling angle that smoothly blends from 30° bevels at the top to 10° bevels at the bottom. No saws do that. You’d have to locate the gradient bevel transitions geometrically and then cut it with a hand saw