Gas Fireplace Flue

Inspected a house which has a natural gas fireplace which has a metal flue passing through the rear side of the roof. The flue (chase) has an arrestor cap on it. The chase extends 3’ above the roof line however the flue is located less than 10’ feet from the 2nd floor dormer and sits at least 8" below the top of the dormer.

My question is, are the clearance specs the same for this gas flue /chase as they are for a regular fireplace chase that being having to sit at least 2 feet above the highest structure within 10 feet of it? Thanks

**Bob **you are not displaying where you are from but here in Ontario we go by the CSA (Canadian Standards Association)
Gas chimney is no less than 2 feet above the highest point of the building within a horizontal distance of 10 ft.

I am in Florida. What you have quoted is the standards I know that exists for a wood burning fireplace. They may exist for a natural gas one as well but not sure, trying to ascertain before I call it out in my report. Thanks

These requirements satisfy all national codes.

Flashing and Top Assembly Using a Cap
Model RHW/RM Metal Cap Termination
Model RHW/RM cap sizes 3" through 12" round are
listed by U.L. for installation on gas vents terminating a
sufficient distance from the roof so that no discharge
opening is less than 2 feet horizontally from the roof
surface. The lowest discharge opening shall be no
closer than the minimum height shown in the Table in
Figure 2. These minimum heights may be used
provided that the vent is NOT less than 8 feet from any
vertical wall. This also means that no installation shall
terminate by piercing a wall with a short pipe and cap.

Vent termination clearance.jpg

Vent termination clearance.jpg

See that is one reason why we need to have where you live on the MB.
Thanks Bob it does not suprize me that it is different.
This is one reason we want a Ontario Organization so we can learn what Ontario wants for standards.
I know that InterNachi follows the 2 ft in 10 ft rule also according to the graphics library for Gas and 3 ft chimney for Wood.

Best way to determine is look up the model of the appliance and follow manufacturer guidelines

Will that be different in Canada?

No our standards are the same for all Gas Appliances because they must be CSA approved and have this lable on all chimneys.

Hi Kevin
Are your AHJ’s enforcing this up there? I’m finding entire subdivisions where this rule is not being followed.

**10’ feet from the 2nd floor dormer and sits at least 8" below the top of the dormer.
Photo please.
If the dormer has a window that open it may be a problem.
****8" inches below the dormerand closer then a 10 foot circumference is the question. Openings, intake vent protrusions that are upstream from the exhaust…


John I am not the AHJ. I follow guidelines from the CSA, OBC and IBC 2006 and say in all my reports: "According to today’s standards"ect ect.

I think you misunderstood my question. I understand that you are a private inspector.
I was asking if the authorities in your area are enforcing this rule during new subdivision developments or not. In my area they are not.

I agree with John. I have seen sub divisions that are lax in code.

Yea, like my neighbourhood. The vents are typically less than one foot higher than the peak.



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