I’ve been looking at this gas vent location from a gas water heater. Roof was roughly 5/12 just outside the picture was an operable window. The distance to the corner wall was roughly 2.5 feet.
Looks “fixed” to me!
Like I said just outside the picture was an operable window.
I worried about location to walls, roof, lack of air flow
Which means nothing without the actual distance measurement.
Cory, the rule of thumb for gas vent termination on a 5/12 pitch roof is a minimum 12” height to bottom of vent cap BUT it should also terminate not less than 2 feet above any portion of a building within 10 feet horizontally. Had the second requirement been met, it’s proximity to the operable window would not be an issue.
As always, check your local ordinances and manufacturers instructions for any variations in this general rule.
5 Likes
I believe that is for chimneys, not vent terminations.
3 Likes
Where did your diagram come from?
This is what I remember:
Table of Type B-Vent Rooftop Clearance Requirements
Vent caps 12" and smaller may terminate a distance above the roof if 8 feet or more away from a vertical surface as follows:
Table of Rooftop Chimney Clearances for Metal B-Vent Chimneys & Flues
ROOF PITCH - rise/run in inches Minimum Height Above the Roof Surface (1)
Flat to 7/12 1.0 foot above the roof surface (1)
7/12 to 8/12 1.5 feet above the roof surface
8/12 to 9/12 2.0 feet above the roof surface
9/12 to 10/12 2.5 feet above the roof surface
10/12 to 11/12 3.25 feet above the roof surface
11/12 to 12/12 4.0 feet above the roof surface
- Continues to 21/12 pitch at 8.0 feet
Notes to the table above
(1) measure on the up-roof or “shorter” height side of the chimney
(2) Watch out: while one foot above the roof surface may meet the recommendations for fire clearances, in one-storey buildings or in buildings with heating equipment on the uppermost floor, the total chimney height may be inadquate to establish sufficient and safe draft unless you extend the chimney height by more than these low minimums.
2 Likes
8 feet is the key. If within 8 feet of a vertical surface/wall the vent needs to go above the upper/main roof.
Now, I’ve never seen a city enforce this though. I’ve seen many times various cities choose not to enforce this
1 Like
Good point Yu. 
Thanks for that clarification to my table.
And a blanket tstatement that it needs to be 2 feet above anything within 10 feet is erroneous and and misleading.
3 Likes
Ask yourself, is the vertical surface 2.5 ft away, 8 feet or more away?
All metal vents must terminate at least 2 feet above the roof surface and anything within 10 feet of the vent , such as the crest of a roof ridge; Type B and Type L Vent Inspection - InterNACHI®.
I stand by this statement:
2 Likes
Larry you’re 100% correct. I use the 503.6.5 image at least twice a month. The InterNACHI one size fits all narrative doesn’t work for me.
3 Likes
Thanks Martin. The InterNACHI image and narrative is indeed NOT ONE SIZE FITS ALL. @bgromicko1 …Maybe it can get changed to be more accurate. 
3 Likes
Hi, @lkage. I think there may be two clearance topics being referenced here. It is a common mistake to apply chimney (masonry) termination height requirements (the 3-2-10 rule) to gas fuel vents, which causes vents to extend above roofs much higher than needed, in most cases. For example, gas vent pipes terminating above roof slopes up to 6:12 need to be only 1 foot high.
The “Fuel Gas Vent Terminations” chapter in InterNACHI’s free, online plumbing course provides some good info on this topic:
1 Like
Hi @bgromicko1
Richard’s image shows a vent (NOT A CHIMNEY) which requires it be 2’ above any object within 10’ horizontally.
If that was changed to 2’ above any object within 8’ horizontally (for vents RE: 2018 International Fuel Gas Code 503.6.5), it may correct the issue. (Manufacturer’s requirements are specific to that manufacturer and a different discussion).
Just a thought.
Incidentally, a chimney is not only masonry but a class A chimney too.
Should be 2ft above any part of the building within 10ft horizontally if it falls into the a) within 8 feet of a wall/similar or b) larger than 12in in diameter. The rule is 2:2:10 but only if triggered by a or b, otherwise the height is listed in the table provided in the code. As always, the manufacturer rules supercede the code.
2 Likes