Thread: Code change for exhausts terminting to exterior only

I was just wondering what average year (or decade) the code changed for exhaust system to terminate to exterior only? From my understand it us to be permitted for exhaust systems (ie bathrooms) to terminate into the attic space and I have seen it in many older homes. I call the def. out whenever I see it, but I was wondering for my own knowledge and if a client were to ask when it changed.

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It was probably like many code sections which have been revised and revised again ... the code does not allow something to be done, but the code wording allowed "interpretation" (stretching may be a better word).

Like saying that all exhausts shall terminate to the outdoors.

A building official rejects a contractor terminating it in the attic ... the contractor tells the building official that the attic air is "outdoor" air because the attic is ventilated ... show me where the code says I can't do that.

The codes do not attempt to regulate common sense ... one contractor gets away with it and the word spreads.

It takes years for enough building officials to be affected, and more years to change the code to say 'hey, dummy contractor, the air in the attic in not outdoor air anymore than the inside air is outdoor air because a window is open ... don't terminate it in the attic'.

IRC 2006 chapter 15 has this verbiage which is not present in IRC 2003 (that I can find.)

"The air removed by every mechanical exhaust system shall be discharged to the outdoors. Air shall not be exhausted into an attic, soffit, ridge vent or crawl space."

So by default whenever the 2006 IRC was adopted.

Originally Posted by Jim Luttrall

IRC 2006 chapter 15 has this verbiage which is not present in IRC 2003 (that I can find.)

"The air removed by every mechanical exhaust system shall be discharged to the outdoors. Air shall not be exhausted into an attic, soffit, ridge vent or crawl space."

So by default whenever the 2006 IRC was adopted.

Jim,

It used to be in a different section - from the 2000 IRC: (underlining is mine)
- R303.3 Bathrooms.
- - Bathrooms, water closet compartments and other similar rooms shall be provided with aggregate glazing area in windows of not less than 3 square feet (0.279 m²), one–half of which must be openable.
- - - Exception:
- - - - The glazed areas shall not be required where artificial light and a mechanical ventilation system are provided. The minimum ventilation rates shall be 50 cfm (23.6 L/s) for intermittent ventilation or 20 cfm (9.4 L/s) for continuous ventilation. Ventilation air from the space shall be exhausted directly to the outside.

"Ventilation air from the space shall be exhausted directly to the outside."

And isn't "attic air" ventilated to the "outside"? That was the argument.

If that was the case, and the "inside" air was required to have ventilation, then the "inside" air would also be "outside" air ... which shot down the argument that the air in the attic was the same as being "outside" - the attic air is just ventilated to the outside at a greater rate than the inside air is ventilated to the outside.

The requirement that bathrooms be ventilated to the outside goes way back even before the 2000 IRC, it was in the Standard Building Code and the other building codes too.

Open a window to let outside air in ... does not mean to open a window and vent it to the attic - so why would a requirement to exhaust the air to the outside be taken as allowing the air to be exhausted to the attic? If the attic was "outside air" then just open the window and have it ducted directly to the attic air ... no one would do that, that would be considered screwy ...

"Ventilation air from the space shall be exhausted directly to the outside."
This is what I remembered and was looking for but could not find.
I think this was a change that started the transition when they added the word "directly" as opposed to just outside.

Here, we had all the different versions of "compliance", just into the attic, maybe with a short pipe to get it above the insulation if you were lucky. Then they started ducting them to blow toward the soffit or upper attic vents, and now through dedicated vents directly outside. Glad it is finally codified in unambiguous terms.
Fortunately, around here it rarely causes a problem since we don't have to deal with ice dams, etc.

Originally Posted by Jim Luttrall

Glad it is finally codified in unambiguous terms.

Many, if not most, code change proposals are "correcting" language which someone found as ambiguous enough to allow them to not meet what most realized the code was saying, so more wording was added, the phraseology was changed, etc, time and time again to final arrive as what it takes to stop "stupid" ... unfortunately, "stupid" will keep trying to find a way around the code until they do, then another code change will be needed to stop that "stupid".

"Stupid" can't be fixed, all the code can try to do is stop "stupid" as much as possible - but should we really have to have an Encyclopedia Britannica-type code to stop "stupid"?

At some point common sense should come into play ... wait, I forgot, "common sense" is no longer "common" ... so we are left trying to stop "stupid".

The bathroom exhaust vents use to be able to terminate in the attic space at the roof vent or to the soffit because the city municipal inspectors considered the attic space as exterior, then the city municipal changed the definition of the attic space as interior and therefor stating that the bathroom exhaust vent need to terminate to the exterior, outside of the attic space. That changed around here in about 2003.