Degrees to Pitch conversion

[Barry Dennis]

Does anyone know the math formula to convert the angle of a roof in degrees to X in 12 pitch?

[jemcon]

If you have a construction master calculator it will do it for you. If not PM me and I'll do it on the calc.

[Kris M]

Divide the rise by the run and take inverse tangent of that and it will spit out the degrees.

Kris M.

[Joe Carola]

Does anyone know the math formula to convert the angle of a roof in degrees to X in 12 pitch?

Barry,

Using a Scientic calculator or Construction Master Calculator. Press the Tan button for any given degree on the plans and multiply by 12 and that will be your pitch.



A Construction Calculator is the easiest one to use.

If you were given a 22.62° pitch on a set of plans, you can this.

22.62 [Pitch] [Pitch] Returns -5 (5/12 is your pitch)



If you have a scientific calculator you can do this.

22.62 [Tan] x 12 = 5 (5/12 is your pitch)

45 [Tan] x 12 = 12 (12/12 is your pitch)

[Joe Carola]

Divide the rise by the run and take inverse tangent of that and it will spit out the degrees.

Kris M.

Kris,

That's only good if your given the rise. I've had some plans that don't give you the pitch or rise , they just give you the degrees of a roof.

[Carl Sperry]

You could just look on the speed square. The pitches & angles are listed on the square & in the book that comes with it.

[littlebluetruck]

this is handy

[Joe Carola]

Barry, What are you using to figure your rafters now?

Are you using a Scientific Calc, Construction Master Calc, Framing Square?

[Joe Carola]

Barry,

Just to give you an example of how you can use Construction Master Trig Calculator.

If you were give a pitch of 22.62° on a set of plans and your common rafter run was 16’ for example without a ridge deduction, you can do this:

Using a Construction Master with Trig:

22.62 [Pitch]

16 [Feet] [Run]

[Diagonal] = 17’ 4” (Common Rafter Length)


Or you can do this:

16 [Feet] [÷] 22.62 [Cosine] = 17’4” (Common Rafter Length)

[Barry Dennis]

Thanks Everyone, I do remodel projects and run into some oddball pitches so I use a Stabilla electronic level which give me the degrees. I've used the speed square to convert to pitch, but if the roof is an oddball, I need to guess at the pitch (sometimes I need to hit an existing height). I use the step-off method to layout rafters.

[curtismilton]

Perhaps this print out will help?

Best of luck,

[Joe Bartok]

Barry, if you are given only the measurement in degrees, since the tangent of an angle is the rise/run you can use this series to solve for Tangent of an Angle.
Be sure you multiply the value of the angle (x in the formula) in degrees by pi/180 to convert it to radians before substituting.
It's a good formula to know if you don't have a calculator but keep a box of pencils and a ream of paper handy ...

Does anyone know the math formula to convert the angle of a roof in degrees to X in 12 pitch?

EDIT: You asked for the "Over 12" value, so after you are done cyphering multiply the result returned by the tangent formula by 12.

[olllee]

Curtis , welcome to the fold

[Housewright]

Call me Old School, but why not just use a square to begin with? if the slope is 5 3/16 on 11 who cares, measure the run off your square and make pitch blocks to set your saws if need be. It doesn't need batteries and it is always right.

[Toolwhore]

Good info. but I still haven't figured out why it's on the Estimating & Mark-up forum.