Replies

1. 
   BossHog | Jun 25, 2012 10:03pm | #1

   Definitely old style.  The number is an argument against 24.

   i.e. 1/3 of 24 is 8, so a 1/3 pitch is 8/12.  

   Or 12 is half of 24, so a half pitch is 12/12.  A "full pitch" is 24/12.

   It's a pain in the neck - Guess that's why they quit using it.

1. 
   DanH | Jun 25, 2012 11:33pm | #2

   On the other hand, it tells you how tall the roof is.  The 1/3 pitch is one third as tall as it is wide.

2. 
   [email protected] | Jun 26, 2012 05:42pm | #3

   One of the guys explained it a bit.

   One of the guys that works for me explained it a bit.  He also said that it is easier on the old framing squares, as some of them had a direct scale for it on the 18-inch leg. 

3. 
   hammer1 | Jun 27, 2012 09:42am | #4

   Roof pitch and roof slope are the same but they are expressed differently. Pitch is described as a fraction, slope is described as rise per foot of run. A roof that has a rise of 4" per 1' of run, 4/12 would be a 1/3 pitch.

1. 
   [email protected] | Jun 27, 2012 11:33am | #5

   Hammer look at the original post, they arent the same.

   That is what caused me to post,  If I calc the rise/over the run based on the dimension,  I get an 8/12, or 2/3 pitch. 

   The stated pitch drawings is 1/3. 

2. 
   BossHog | Jun 28, 2012 06:48pm | #6

   If you read the first post I did in this thread it explains it. It's a very old way of expressing roof slopes, and has nothing to do with conventional ratios expressed as a number over 12.

1. 
   DanH | Jun 28, 2012 10:10pm | #7

   Yeah, as I suggested, I'd bet that it comes from observing the finished roof and noting that the height is, eg, 1/3rd the width.