# Vents  Thru  The  Roof



## north star (May 3, 2018)

** = * = **

I am seeking input from the Forum on Vents thru the Roof ( VTR's ).

On some military plans that I have been reviewing recently, it has been
discussed [ by some ] to NOT have any penetrations in any of the roofing
systems.........This idea is intended to extend the life of the roofing
systems.

Do any of you adopt this approach ?

Thanks for your input !

** = * = **


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## ICE (May 3, 2018)

We do not limit roof penetrations.  I have worked a few military projects....I’m imagining ten pages on how to not penetrate the roof.


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## mtlogcabin (May 3, 2018)

903.5 Location of vent terminal.
An open vent terminal from a drainage system shall not be located directly beneath any door, openable window, or other air intake opening of the building or of an adjacent building, and any such vent terminal shall not be within 10 feet (3048 mm) horizontally of such an opening unless it is 3 feet (914 mm) or more above the top of such opening.

903.6 Extension through the wall.
Vent terminals extending through the wall shall terminate at a point not less than 10 feet (3048 mm) from a lot line and not less than 10 feet (3048 mm) above average ground level. Vent terminals shall not terminate under the overhang of a structure with soffit vents. Side wall vent terminals shall be protected to prevent birds or rodents from entering or blocking the vent opening.


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## north star (May 4, 2018)

*$ = $*

Thanks ***ICE***  &  ***mtlogcabin*** for your input !

*$ = $*


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## steveray (May 4, 2018)

VTW.....Like MT said if you don't want the hole in the roof...


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## Pcinspector1 (May 4, 2018)

Government building, "Is it hot air their venting?"


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## Paul Sweet (May 4, 2018)

When designing a building I try to combine vents in the attic to the greatest extent practical and minimize the number of roof penetrations, both for appearance and to reduce the number of potential leak points.


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## mp25 (May 4, 2018)

I wonder if AAV would be an option under the code that you are working with - although it would be one more thing for the building engineer to worry about.


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## north star (May 5, 2018)

*# = # = #*

mp25,

Thanks for your input !

I would not choose to use AAV's for venting.....I consider them
to be mechanical devices with moving parts, that at some
point in the future, WILL stop working !......That could possibly
cause a detrimental effect on removal of the sanitary sewer
gases in the lines.......Plus, diagnosing a failed AAV somewhere
in the installed vents would be problematic [ IMO ].

It is my intent to change the mindsets of Leadership and some
RDP's, by removing all roof penetrations in the design and
actual installation of the plumbing systems........It CAN be done.
It just needs a different and compliant way to do it.

*# = # = #*


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## conarb (May 5, 2018)

north star said:


> *# = # = #*
> 
> mp25,
> 
> ...


North Star:

In the late 50s I took a magazine published by the NAHB, it was a nice glossy magazine that isn't published anymore.  I remember an article published in about 1959 about a test house built in a tract of homes in I believe Arizona.  The test house had all the vents combined in the attic into one ½" copper pipe that ran horizontally emerging through the eves, at the time the test house had performed with no problems for a couple of years, if I remember correctly the system was fought by the plumbers' unions because it would reduce work for plumbers.


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## ADAguy (May 11, 2018)

Hmm, chimneys still look good on buildings even if not used as originally intended.


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## Jimmy T (Mar 25, 2021)

Lots of metal roofs going on around here, no one wants to put a hole in the metal so thru the wall is really popular, usually on a backside gable all the way at the peak then turned up above the roof. Lots of bathroom exhaust fans thru gable walls or out thru soffits. Still have people regularly wanting to let exhaust fans blow into the vented attic and forget about it.


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## Teeshot (Mar 29, 2021)

In CA, each vent shall terminate vertically, at least 6-inches above the roof. Combining vents prior to penetrating the roof is common, but the aggregate cross-sectional area of the vent(s) shall not be less than that of the largest required building sewer.


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## ADAguy (Apr 14, 2021)

In summation, how is eliminating penetrations going to extend roof life if the attic is properly vented to reduce heat build up?


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