Expert: Dave Johnson - 8/27/2008

Question
QUESTION: Iam putting an addition on my present home which measures 8'x24' and need a formula for cutting the roof trusses.

ANSWER: Hi Al,
I would need to know the pitch you are trying to achieve to get the degrees... Also I'm assuming the rafters are running the 8' way...
Dave

---------- FOLLOW-UP ----------

QUESTION: I want to raise them 32 inches and they are running the 8' way

Answer
Hi,
Thats called a 4/12 pitch. (meaning that the rafter rises 4" in every 12" of run)
If you hold a framing square with 12" on one leg and 4" on the other, both on the same edge of your rafter, mark both sides  and repeat (starting each new measure at the previous one) for every foot of run (eight).
When this is done, one end will be cut for the top (ridge) and the other will be for the plate.
On the plate cut, only cut in about an inch and a half, then cut at
right angles to that on the upper or ridge side for the "birdsmouth" to sit on the plate.
Be sure to leave enough material extending out from the plate for your overhang...
If this is not clear, please mail me again I sure wish we had graphics here...
Good luck,
Dave