I'm a Framing Contractor in New Jersey for the past 19 years. I've cut many different types of roofs befor and up until about a year ago started to use a calculator.

I use a Construction Master Pro Tirg Plus III.

I've been particapating on the Rough Framing Forum for The Journal of Light Construction for the past year.

There's has been many conversations about roof framing that I brought up because that is my favorite part of Framing.

We've discussed many ways of framing "Bastard Hips" or "Irregular Hips".

90° walls with two different pitches. Maim roof(Front to back) can be 8/12 Pitch. Side Roof can be 10/12 pitch.

There's alot of discussions about Formulas for these roofs such as.

Figure Pitch of Hip.
Hip In Plan View.
Hip/Valley offset to equal overhangs and Fascias.
Hip Lengths.
Cheek Cuts.
Backing Bevels.
Hip Drop.
Plate height Difference to equal overhangs.
Jack Rafter Difference for both pitches.
Plywood Angles.
Different overhangs when Hip sits on the corner.

I know Timber Framing is different than Stick Framing but to figure out rafters in the situations I listed above or any Roof situation has to be the same wether you use just your Framing Square, Calculator, Scientific Calculator using all Trigonometry, Construction Master Calculator With Trigonometry in it.

The Construction Master Calculator has a lot to offer. For example, 8/12 Pitch and 10/12 Pitch Roof. A few different ways.

8 [Inch] [Pitch]

12 [Inch] [Run]

10 [Inch] [Conv][Hip/Val]

Press [Hip/Val]Twice Returns - 17.325" (Hip Length)

Press [Hip/Val] Returns - 27.50° (Hip/Valley Plumb Cut)

Press [Hip/Val] Returns - 62.50° (Hip/Valley Level Cut)

Press [Hip/Val] Returns - 38.66° (Plan View Angle 10/12 side)

Press [Hip/Val] Returns - 51.34° (Plan View Angle 8/12 side)

Or to figure the Hip/Valley Plunmbcut.

10/8 = 1.25

Press [Conv] [Tan] Returns - 51.34019°

Press [Pitch]

12 [Inch] [Run]

Press [Diagonal] Returns - 19.20937

10/19.20937 [=] [Conv] [Tan] Returns 27.5005°

Or This.

10/8 [=] 1.25

Press [Conv] [Tan]= 51.34019°

Press [Cos] x 10 [Inch] [Pitch] Returns - 27.50°

Or This.

51.34019 [Pitch]

12 [Inch] [Run]

Press [Diagonal] Returns 19.20937

Press [=] [Run]

10 [Inch] [Rise]

Press [Pitch] Returns 27.50°

These are just different ways of using the CMP calculator.

I have alot of Formulas on the CMP calculator that I've come up with to simplify Irregular/Bastard Hip Roof situations.

I found a thread here by Dave Gee, "Hawkindale Angkles".

Dave and Ed Levin discuss Hawkindale's Formulas.

It's a very interesting thread.

I'm going to try and find out more on Hawkindale's Formulas.

Do all Timber Framers use Hawkindale's Formulas or does everyone use their own?

I would love to go to a Timber Framing seminar on Roof Framing.

Sorry for the long post but I have a great passion for Framing and what I do for a living and I'll never stop trying to learn something new.

Joe Carola