Vent pipes should extend to outdoors above the building roof and should terminate vertically not less than 6 above the roof surface nor more than 24 and must be at least 12 from any vertical surface such as a nearby sidewall.
Vent pipe height above roof.
Single wall metal pipe shall terminate at least 5 feet 1524 mm in vertical height above the highest connected equipment draft hood outlet or flue collar.
Let s look at a couple of examples.
From any vertical surface the soil pipe also known as the vent stack or stack pipe provides air for the plumbing system.
All open vent pipes that extend through a roof shall be terminated at least 6 inches 152 mm above the roof and not less than 2 inches 51 mm above the invert of the emergency overflow except that where a roof is to be used for any purpose other than weather protection the vent extensions shall be run at least 7 feet 2134 mm above the roof.
We install our roof vents 6 to 8 inches above the roof line.
You are close to your eave and you find that your measurement is 18 feet from peak to penetration on a 4 12 pitch see figure 3.
Upc i 906 1 and 906 2.
The vent is supposed to be 10 away or 2 above any window.
Above the roof nor less than one 1 foot.
For those stinky vents consider installing odor hog vent caps see image on the roof vents.
According to the uniform plumbing code the soil pipe or stack pipe shall extend vertically not less than six 6 inches.
Above the roof plumbing vent height.
This may seem suitable since the only purpose for the stack is to provide air and expel sewer gases.
However it needs to be at least six inches above your fixture s flood level to keep from getting wet.
A note on the main drain.
I am sure the plumber put it at that height for the inspector.
Many people mistakenly think that the pipe always has to be 2 feet above the roof peak.
Single wall metal pipe shall extend at least 2 feet 610 mm above the highest point where it passes through a roof of a building and at least 2 feet 610 mm higher than any portion of a building within a horizontal distance of 10 feet 3048 mm.
If the roof area is for people then it is 7 ft above the roofing surface.
For 18 feet of run you would have a rise of 72 inches.
On a sink that would be either the rim or overflow hole.
You should be able to cut that vent shorter but stay above the roof line.