plumbing vent location

[Thomas Hudson]

Hi everyone, long time lurker here. I inspected a home last night where the vent for the kitchen sink ran directly to the exterior and up 5 feet terminating 3 feet below the eave. I have always seen vents go through the roof or as a studor, is there any reason why it can't terminiate on the side of the house. The was a 50 year old ranch. Thanks!

Tom

[Jerry Peck]

where the vent for the kitchen sink ran directly to the exterior and up 5 feet terminating 3 feet below the eave.

Tom,

First, if run outside above the design temperature freeze line (which is about from Jacksonville, Fl, through Tallahassee, through Pensacola, and along that line, which puts all of NC in the 32 degree freeze design temperature and colder) not only does the piping need to be enclosed for physical protection, it also needs to be within the insulated thermal envelope of the house.

That vent 'might' be able to be an AAV (Air Admittance Valve, such as Studor or Oatey make), but there are conditions for their use, one of which is that at least one vent opens to outdoor air, and that kitchen vent may be 'that one'?

[Thomas Hudson]

Thanks Jerry, I noted the freeze issue in the report and that it should be going through the roof via the interior. Its also less than a foot from a window so thats a no no anyway.

Tom

[Jerry Peck]

Its also less than a foot from a window so thats a no no anyway.

Yeppers, that'd be correct.

Maybe they just like the smell so much they add it to the cooking odors? :)

The smell of freshly baked bread and ... well, maybe not ...

[John Dirks Jr]

Tom,

First, if run outside above the design temperature freeze line (which is about from Jacksonville, Fl, through Tallahassee, through Pensacola, and along that line, which puts all of NC in the 32 degree freeze design temperature and colder) not only does the piping need to be enclosed for physical protection, it also needs to be within the insulated thermal envelope of the house.

That vent 'might' be able to be an AAV (Air Admittance Valve, such as Studor or Oatey make), but there are conditions for their use, one of which is that at least one vent opens to outdoor air, and that kitchen vent may be 'that one'?

I'd like to dredge up the issue here. The IRC says the following:

P3101.4 Extension outside a structure.

In climates where the 97.5-percent value for outside design temperature is 0°F (-18°C) or less (ASHRAE 97.5-percent column, winter, see Chapter 3), vent pipes installed on the exterior of the structure shall be protected against freezing by insulation, heat or both. Vent terminals shall be protected from frost closure in accordance with Section P3103.2

FIGURE R301.2(1) of the IRC puts the above referenced line up in New York State.

What am I missing? I'm working with a similar exterior vent issue in the central Maryland area. I don't see where the IRC launguage prohibits it in my area. Maryland is in the 15 degree F range according to the chart.

[Jerry Peck]

I'd like to dredge up the issue here. The IRC says the following:

P3101.4 Extension outside a structure.

In climates where the 97.5-percent value for outside design temperature is 0°F (-18°C) or less (ASHRAE 97.5-percent column, winter, see Chapter 3), vent pipes installed on the exterior of the structure shall be protected against freezing by insulation, heat or both. Vent terminals shall be protected from frost closure in accordance with Section P3103.2

FIGURE R301.2(1) of the IRC puts the above referenced line up in New York State.

What am I missing? I'm working with a similar exterior vent issue in the central Maryland area. I don't see where the IRC launguage prohibits it in my area. Maryland is in the 15 degree F range according to the chart.

What are you missing?

Two things:
- "Extension", that is the extension outside the structure, i.e., the through the roof vent would be one where there is a portion 'within the structure', i.e., within the attic, and then a portion "exterior of the structure", i.e., through the roof and above.
- "CHAPTER 31 VENTS", that section is only for vents and the vent section of the pipe.

I have referred to the DWV piping which is outside the structure, not just the vent portion through the roof, etc..

From the IRC: (bold and underlining are mine)
- P2603.6 Freezing. In localities having a winter design temperature of 32°F (0°C) or lower as shown in Table R301.2(1) of this code, a water, soil or waste pipe shall not be installed outside of a building, in exterior walls, in attics or crawl spaces, or in any other place subjected to freezing temperature unless adequate provision is made to protect it from freezing by insulation or heat or both. Water service pipe shall be installed not less than 12 inches (305 mm) deep and not less than 6 inches (152 mm) below the frost line.

Here is an example of a combined installation which would require one thinking about what they are doing to prevent an installation which was not code compliant:
- Let's say you have an older structure with the soil and waste piping in the crawlspace, the soil or waste piping goes horizontally (sloped) to an exterior wall, turns vertical, catches a kitchen sink, continues up the wall and catches a lavatory, then continues up the wall and stops below the roof (which in and of itself creates its own problems).

The only part of that pipe not required to be protected from freezing at 32 degrees F is "the vent" portion up above the lavatory, and that is required to be protected at 0 degrees F. Even this portion is debatable as this is not an "extension" as such, so it could successfully be debated (I have for years) that this needs to be protected from freezing the same as the rest of the pipe at a winter design temperature of 32 degrees F. See why below.

ALL of the piping below "the vent" portion, all the way the wall and into the crawlspace is required to be protected from freezing at a winter design temperature of 32 degrees F.

Now, a different example:
- Let's say you have a newer house with all the piping within the walls of the structure, the DWV piping needs to be protected from freezing at 32 degrees F winter design temperature ... except the penetration through the roof and above, which needs to be according to this:
- P3103.2 Frost closure. Where the 97.5-percent value for outside design temperature is 0°F (-18°C) or less, every vent extension through a roof or wall shall be a minimum of 3 inches (76 mm) in diameter. Any increase in the size of the vent shall be made inside the structure a minimum of 1 foot (305 mm) below the roof or inside the wall.

In P3103 you will note that there are two types of "extensions" addressed - yes, that word "extension" is key to your question and the answer - these two extension types are: "Roof extension" (see P3103.1) and "Extension through the wall" (see P3103.6). You will note that in my first example the "vent" portion of the pipe going up the wall was not an "extension", which is why it too should be protected at the winter design temperature of 32 degrees instead of 0 degrees.

Hopefully that helps explain it.

[James Duffin]

Hi everyone, long time lurker here. I inspected a home last night where the vent for the kitchen sink ran directly to the exterior and up 5 feet terminating 3 feet below the eave. I have always seen vents go through the roof or as a studor, is there any reason why it can't terminiate on the side of the house. The was a 50 year old ranch. Thanks!

Tom

The house has to meet the code it was built under....not the current code. I would write it up as a repair item and if the seller could find a plumber who would put in writing that is was OK in 1960 I would not argue with him.

[Jerry Peck]

Hi everyone, long time lurker here. I inspected a home last night where the vent for the kitchen sink ran directly to the exterior and up 5 feet terminating 3 feet below the eave. I have always seen vents go through the roof or as a studor, is there any reason why it can't terminiate on the side of the house. The was a 50 year old ranch. Thanks!

Tom


The house has to meet the code it was built under....not the current code.

James,

Which part does not meet current code?
- Running up the exterior wall?
- Terminating 3 feet below the eave?

[H.G. Watson, Sr.]

An auxiliary vent can be. Frost protection simply means for those smaller vents to increase the trade size by two at least a foot within the structure's envelope.An auxiliary vent is a dry vent no part of it normally transmits water, soil or waste. A wet vent would be subject to freeze protection.By the way, a vent is likewise not an interior metal water pipe either. ;)

[John Dirks Jr]

Thank you Jerry, that does clarify it for me. The deciding factor for protection at 0 degrees or 32 degrees would be whether a portion of pipe was vent only, or, vent and waste combination.

[Jerry Peck]

Thank you Jerry, that does clarify it for me. The deciding factor for protection at 0 degrees or 32 degrees would be whether a portion of pipe was vent only, or, vent and waste combination.

Don't forget the "extension" part too.

The "extension" may be at 0 degrees under those conditions, the rest is all at 32 degrees.