B vent inside home

[Tom Breslawski]

I just inspected a home today that had B vent from the basement furnace/water heater exposed inside the house all the way up through the kitchen on the 1st floor and bedroom on the 2nd floor.

I know it's probably a stupid question, but.... is this allowable?

I can't find anything on it and my brain is kind of fried at this point....

Thanks!

[Bill Kibbel]

I don't think it's specifically prohibited in the text of the code. I remember finding it in the code commentary that this issue should be covered by the vent manufacturer's instructions.

Except for the room where the vent originates, it needs to be protected from damage and from combustibles contacting the vent. Some manufacturers specify a chase with a specific fire resistance rating.

And then there's the required fire stop collars/spacers at each ceiling/floor penetration.

[Tom Breslawski]

Thank you.

I couldn't come up with anything at all. I'll double check the manufacturer's instructions. Fire blocking was not in place and has already been written up.

Thanks again!

I don't think it's specifically prohibited in the text of the code. I remember finding it in the code commentary that this issue should be covered by the vent manufacturer's instructions.

Except for the room where the vent originates, it needs to be protected from damage and from combustibles contacting the vent. Some manufacturers specify a chase with a specific fire resistance rating.

And then there's the required fire stop collars/spacers at each ceiling/floor penetration.

[Jim Katen]

I can't find anything in the IRC or the manufacturers' instructions to prohibit it. (I checked Metal Fab, Amerivent, and Duravent.)

I'd just explain that the vent is always supposed to have 1-inch of clearance to combustibles and that it might be a good idea to build some kind of chase, guard, or cage around it.

[Bill Kibbel]

I can't find anything in the IRC or the manufacturers' instructions to prohibit it. (I checked Metal Fab, Amerivent, and Duravent.)

I researched this years ago for expert witness work. Here's 3 from instruction PDFs on my laptop. I'm sure I have more at the office desktop.

Selkirk: "Gas vents which extend through any story above that on which the connected appliance is located are to be provided with enclosures having a fire resistance rating equal to or greater than that of the floor or roof assemblies through which they pass."

Hart & Cooley: "Portions of gas vents that may pass through accessible spaces must be enclosed to prevent personal contact with and possible damage to the vent. The enclosure also may have to meet fire resistance rating provisions."

Duravent: "Any portion of the vent which passes through an occupied area must be enclosed, to prevent accidental damage to the system, as well as burns."

Commentary: "Physical protection of the vent system is required to prevent damage to the vent and to prevent combustibles from coming into contact with or being placed too close to the vents. Such protection is typically provided by enclosing the vent in chases, shafts or cavities in the building construction. Physical protection is not required in the room or space where the vent originates."

[Jim Katen]

Thanks. I must be losing it.

If you get a chance, see if you have a similar quotation from Metal-Fab. I still can't find it there.

[Rob Amaral]

Excellent response as usual Bill Kibbel and Jim Katen..

But you forget pg. 375: "Use common sense when using this stuff.. "

[mjr6550]

Thanks. I must be losing it.

If you get a chance, see if you have a similar quotation from Metal-Fab. I still can't find it there.

I look at Metal-Fab. This is the closest thing I could find:

"10. When installing exterior vent, not enclosed by the structure or a

chase, consult local gas utility, appliance manufacturer, and/or

authority having jurisdiction."

I did not see any requirements to enclosed at the interior. I agree that it is not code required, other than if the manufacturer requires it, then it becomes code required.

[Jim Katen]

Thanks. I must be losing it.

If you get a chance, see if you have a similar quotation from Metal-Fab. I still can't find it there.

I look at Metal-Fab. This is the closest thing I could find:

"10. When installing exterior vent, not enclosed by the structure or a

chase, consult local gas utility, appliance manufacturer, and/or

authority having jurisdiction."

I did not see any requirements to enclosed at the interior. I agree that it is not code required, other than if the manufacturer requires it, then it becomes code required.

Which is frustrating when 3 of the four major manufacturers require it, but the 4th doesn't. It means that I have to figure out the brand before I write up the issue. Woof!

[Bill Kibbel]

Which is frustrating when 3 of the four major manufacturers require it, but the 4th doesn't. It means that I have to figure out the brand before I write up the issue. Woof!

Or, you can state most of the major manufacturers require it and what Rob says above.

[Tom Breslawski]

Thanks to all for the info. It was a Duravent and I recommended building a chase or enclosure around it.