# Finding length of gable boards



## joed (Mar 13, 2005)

AT 32 feet wide and 6 feet high in center you have 17.088 feet on each gable roof.
The pitch is actually 4.5/12.


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## Joe Carola (Apr 14, 2006)

Borske said:


> Is there a formula for figuring out the length of a gable fascia board?
> I have the width of the gable (32') and I have the height (6') the pitch/rise is 4-12
> Im trying to figure out the amount of soffit & fascia I need to order without having to climb up on the roof to measure the actual 1x6 boards.
> 
> Thankyou


32' gives you 16' for the run and 6' for the rise, so your pitch is 4.5/12 and the length is 17'1-1/16" , if this was all exact.

You have to figure at least 18' of rake.

The formula is (a squared )+ (b squared) = (c squared).

That's just one way. there are many.


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## Borske (Jul 20, 2006)

Thankyou for your responses.
Can you tell me how you both figured that the rise is 4.5? What formula did you use to find this.


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## Bonus (Aug 25, 2005)

rise/run=6'/16'=4.5/12


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## Joe Carola (Apr 14, 2006)

Borske said:


> Thankyou for your responses.
> Can you tell me how you both figured that the rise is 4.5? What formula did you use to find this.


Theres are many ways to figure this dpending how good you are with math and what your comfortable with.

One way is like this;

rise/run x 12 = (pitch)

Your example with a 6' rise and 16' run.

6/16 = .375 x 12 = 4.5


That will get you close to what you want but that will not be your pitch because your 6' is to the top of the rafter at the ridge line and that doesn't account for the rafter thickness and the H.A.P. cut (height above plate) which is the plumbcut line measured on the outside of the top plate vertical to the top of the rafter after you cut your birdsmouth. Once you cut the level seatcut out you measure this. This means that your pitch will be lower than 4.5/12.

That 4.5/12 is with a perfect triangle with a 6' rise and 16' run giving you a 17' 1-1/16" diagonal. You will have a different pitch and measurement with whatever rafter stock you use.


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## Borske (Jul 20, 2006)

I forgot to say thankyou...
Thankyou!


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