Replies

1. 
   mitch | Mar 30, 2004 10:39pm | #1

   the march '04, #161, issue of fhb might have what you're looking for.  might still be on newstands- #162 just came out.

   m

1. 
   Metacraft | Mar 31, 2004 12:04am | #2

   thank you. I will run right out & get it.

   Patrick

2. 
   ErikR1 | Mar 31, 2004 12:25am | #3

   Patrick,

   Ya lost me a little. Are you slipping valleys into an existing roof  and looking for the ridge angle on your valley rafter or are you lookin for the combo cut on the bottom of a california jack rafter?

   If your looking for the california jack cut. Hold the square on 3:12 and mark your level cut (the 12'' side) and your undercut for the 7:12 would be setting your saw at 30 1/4 degrees.

   Hope that helps,

   Erik

3. 
   dieselpig | Mar 31, 2004 02:20am | #4

   I'm sure someone will be along to talk you through this step by step.  I'm no mathematician and I'm even worse at teaching, so I won't put you through that.

   I've framed quite a few tricked out roofs and gotten hemmed up trying to figure cuts in complicated roofs.  When all else fails, I string the line of the rafter I'm trying to figure.  If your string is in the same position as your rafter will be, you can read just about every angle you need to know with a speed square.  String and a speed square have gotten me out of more head-scratchin' jams than you can imagine.

   The bonus is that after you see the angles and the "string rafter" in position it will make more sense.  You'll learn more figuring it out this way for yourself than you will if someone just shouts the angles out at you or guides you through the keystrokes on a calculator.

1. 
   JohnSprung | Apr 01, 2004 02:07am | #8

   >... string the line of the rafter ....

   The other advantage of this method is that it fits your rafter to the actual rather than theoretical dimensions. 

   Another variation is to have your helpers hold (or clamp) the piece of two by in a position parallel to and right above where it needs to go, so its bottom is where its top will be.  Then go around with pencil and square, and transfer the marks you need vertically onto it.  This would be too time consuming for professional work, but for a once in a lifetime DIY job it can be the safest way to get it right the first time.

   -- J.S.

4. 
   bd342 | Mar 31, 2004 04:27am | #5

   30' total span / 2 = 15'

   15x5=75"

   75"+ 6"= 81"

   That is pretty close to your 7' total rise so

   based on the info provided I'm thinking you have an existing 5:12 pitch

   You would be foolish to frame it as anything other than a california valley so that gives you a 75 deg. angle with a 22 1/2" bevel cut on your valley jacks.

1. 
   ErikR1 | Mar 31, 2004 11:08pm | #6

   hmm in his post it says 7''. I thought he was talkin 7:12  since he wrote 7''. If his total rise is 7 feet and his span is 30' then:

   rise 84'' / 15'' = 5.6  (5 1/2 on 12)

   His undercut would be 24 1/2 degrees.

1. 
   ErikR1 | Mar 31, 2004 11:30pm | #7

   oops big difference between ' and ''. =)

   rise 84'' /  run 15' = 5.6''  (5 1/2 on 12)

2. 
   bd342 | Apr 01, 2004 04:12am | #10

   you are forgetting the heel height.

1. 
   ErikR1 | Apr 01, 2004 11:01pm | #11

   Your right! I forgot about that! My appologies. =)

5. 
   maliseetroofer | Apr 01, 2004 03:27am | #9

   why go throught all the math and hire a professional roofer. Trust me it saves time and money