Vent Height Above Roof

This reduces the actual required height by 12 inches from our previous calculation of 64 inches.

Vent height above roof.

Gas vents 12 inches 305 mm in size or smaller with listed caps shall be permitted to be terminated in accordance with figure g2427 6 5 provided that such vents are at least 8 feet 2438 mm from a vertical wall or similar obstruction. Please note that this rule doesn t generally apply to pellet and gas vent systems. So 28 inches plus 24 inches is a chimney height of only 52 inches. 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.

The 6 you describe should be just fine. You are letting air into the plumbing system of the house. A vent stack is not like a chimney which requires 2 higher than any roof within 10. The slope is about 4 high for every 12 horizontal.

Above the roof surface with a listed cap or listed roof assembly. Per the 10 and 2 rule once you are at the level of the peak you only need to be 2 feet above it. 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. Open vent pipes that extend through a roof shall be terminated not less than 6 inches 152 mm above the roof.

Where a roof is to be used for assembly or as a promenade observation deck sunbathing deck or similar purposes open vent pipes shall terminate not less than 7 feet 2134 mm above the roof.