For 18 feet of run you would have a rise of 72 inches.
Hight of vent pipe above roof park county colorado.
1 5 feet above the roof surface.
Illustrations of proper gas fired water heater venting using type b double wall vent pipe through a roof above or through a chimney below include details for the flue vent connector such as the requirement of a minimum vent connector upwards slope of 1 4 per foot of horizontal run.
1 0 foot above the roof surface 1 7 12 to 8 12.
You should be able to cut that vent shorter but stay above the roof line.
Extension of vent pipes through a roof shall be terminated not less than 12 inches above it.
P3103 1 roof extension.
I am sure the plumber put it at that height for the inspector.
Vent hight above roof cold climate.
But it is on the edge of the roof so that should not be a problem.
From the irc and other plumbing codes.
2 0 feet above the roof surface.
Roof pitch rise run in inches.
The vent is supposed to be 10 away or 2 above any window.
Permits initiated before february 1 will stay under 2015 code requirements.
A connection between a vent pipe and a vent stack or stack vent shall be made at not less than 6 inches 152 mm above the flood level rim of the highest fixture served by the vent.
If the roof area is for people then it is 7 ft above the roofing surface.
Where a roof is to be used for any purpose other than weather protection the vent extensions shall be run at least seven feet above the roof.
A vent terminal and depending if the roof is strictly for weather protection it terminates about 24 above the roof.
If the previous calculation results in the required height of 64 inches we can see that the top of the pipe will not rise above the roof peak but would still meet the requirements of the rule.
You must also consider the snow line so the pipe does not get covered.
2 5 feet above the roof surface.
Horizontal vent pipes forming branch vents relief vents or loop vents shall be located not less than 6 inches 152 mm above the flood level rim of the highest.
Table of rooftop chimney clearances for metal b vent chimneys flues.
Minimum height above the roof surface 1 flat to 7 12.
For the next example you have a shorter chimney height.