"The gas vent must be at least two feet higher than any part of the roof
within a 10 [foot] radius."

On a 5-12 pitch if the pipe exits at the mid point of the average roof on
the back side of the house I seriously doubt that it will need to be above
the ridge. *The steeper the pitch the taller the pipe. 2 foot is enough on
most 5-12s. *Mine is slightly taller as my pitch is greater.


The 10 foot radius rule - does that mean 10 feet as measured along the
roof, or 10 feet horizontal distance? On a 5-12 pitch roof, if you go
out from the chimney emergence point 10 feet horizontally, the
roofline is then at (10/12) X 5 feet, or 50 inches, plus 24 means your
chimney must stick up 74 inches above the point where it emerges from
the roof. If the rule means 10 feet measured along the roof, that
would be (10/13) X 5 feet, or 46 inches, so the chimney would only
have to stick up 70 inches overall. Not a big difference, but could
be if the inspector is a stickler. Not sure where you get "2 foot is
enough on most 5-12s." --H