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Brandon Whitmore

Bath exhaust duct venting requirements

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I am away from my office / book right now, but am being challenged on something I wrote up.

A bath exhaust fan was not vented to the exterior (no duct). I wrote if up and specified that they vent directly to the exterior. All they did was push up a duct near the roof vent opening; my re- inspect report indicated the need to vent DIRECTLY to the exterior. The HVAC guy send a retort saying that I am wrong and that it meets code. Do any of you have the code or commentary handy that I can send out to them tonight?

Here's what I have so far:

Air must be exhausted directly to the outside 2006 IRC [303.3X]

May not discharge to crawlspace or attic 2006 IRC [1501]

And from a couple of manufacturers instructions:

NuTone

Broan

I know that many/ most building officials are keying in on the word "directly", and making contractors do more than just push the ducts up near a roof vent, and have seen why many times. Does the commentary address this?(I hope)

TIA.

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Brandon,

From the 2006 IRC Code/Commentary. The commentary says that pointing to an existing static vent cap or such is not acceptable.

===================

M1501.1 Outdoor discharge. 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.

Exception: Whole-house ventilation-type attic fans that

discharge into the attic space of dwelling units having private

attics shall be permitted.

The primary intent of this section is to avoid exhausting

contaminants into areas that may be occupied by people

or into concealed spaces such as attics and crawl

spaces where moisture can damage the building components.

To prevent the introduction of contaminants

into the ventilation air of a building, exhaust openings

must not direct exhaust so that it could be readily

drawn in by a ventilating system. In this situation, the

code official must determine an appropriate separation

or location for the placement of intake and exhaust

openings.

Attics and crawl spaces are not considered to be

outdoors. Exhaust ducts cannot terminate in these

spaces. Exhaust ducts must connect directly to terminals

that pass through the building envelope to the outside

atmosphere. Pointing, aiming or similarly directing

an exhaust pipe or duct at an opening in the

envelope of the building (that is, attic louver, grille,

ridge vent, eave vent or soffit vent) in no way ensures

that all or any of the exhaust will reach the outdoors. In

fact, it is possible that the majority, if not all, of the exhaust

vapors and gases will discharge to the attic

space rather than to the outdoors.

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FWIW, in my area on both sides of the state line 99.99% of new construction fans vent next to a ridge vent. At least in my area, I haven't seen any problems from it being done (not saying it's right, just haven't seen problems from it). I used to push to have people get them vented direct to the exterior on inspections, but have never seen any issues on 30+ year old houses without the extensions even ever being near the ridge vents (my own included). I now just recommend they extend them next to a ridge vent if the attic ventilation is done properly.

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Awesome-- thanks Nolan.

I was saying that placement of the ducts at/ near a vent didn't cause any problems a year or two back, and had a good debate over at IN. Since then, I've been paying close attention and have noticed some issues even when the duct is pushed right up to the screening. I'm not sure why, but there are times when the screening on the vents mold and plug up.

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Thanks Nolan,

I have some pictures of my own somewhere, but not near as good as his.

First e- mail from listing agent:

The HVAC contractor will be sending me a note stating that his venting of the bath fan is done to current code. For the record, he came highly recommended to me years ago from XMI Home Inspectors, and he is a senior expert in his field, self-employed as such for 20+ years.

My reply was quite long and boring, so here was what I received via e- mail today [:-monkeyd

Buyer's Agent: "Read below - you win. Of course you did. I will need you to let me know if their itemized list of repairs for the siding will do the job, as it looks good to me.

Thanks again, you kick ass."

Listing Agent: "So, my assistant Katlin called Ron about faxing the cited code stuff to him, and apparently he had already called the city and learned that current code would in fact require a correction on his part, so he will be addressing that tomorrow at the property himself."

Thankfully, the code guy he spoke with knew what he was talking about, or this could have been drawn out, with or without all of the supporting documentation.

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In my climate, they not only need to be vented to the outside, but they also need to be sealed tight.

On the flip side, I've seen houses aplenty with plank sheathing and minimal attic insulation, where a loose bath vent hose has not caused any problem whatsoever.

Newer tight house with well insulated attic, no moist air is allowed.

Here's a couple of recent stains I had to talk about.

The first pic is directly above the master bath shower exhaust fan, short vent pipe straight up through the roof. Number two was a flaky duct tape seal.

Click to Enlarge
tn_2011719192844_Bath%20vent%20leak.jpg

67.61 KB

Click to Enlarge
tn_201171919292_Bathventleak2.jpg

49.7 KB

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Thanks Nolan,

I have some pictures of my own somewhere, but not near as good as his.

First e- mail from listing agent:

The HVAC contractor will be sending me a note stating that his venting of the bath fan is done to current code. For the record, he came highly recommended to me years ago from XMI Home Inspectors, and he is a senior expert in his field, self-employed as such for 20+ years.

My reply was quite long and boring, so here was what I received via e- mail today [:-monkeyd

Buyer's Agent: "Read below - you win. Of course you did. I will need you to let me know if their itemized list of repairs for the siding will do the job, as it looks good to me.

Thanks again, you kick ass."

Listing Agent: "So, my assistant Katlin called Ron about faxing the cited code stuff to him, and apparently he had already called the city and learned that current code would in fact require a correction on his part, so he will be addressing that tomorrow at the property himself."

Thankfully, the code guy he spoke with knew what he was talking about, or this could have been drawn out, with or without all of the supporting documentation.

Go figure, a sub contractor trying to show up a home inspector by using code. Well maybe it was when he started 20+ years ago. "It was too hot to do it right"

Maybe you could add "kicks ass" to your buisness card. Nice complement.

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Thanks Nolan,

I have some pictures of my own somewhere, but not near as good as his.

First e- mail from listing agent:

The HVAC contractor will be sending me a note stating that his venting of the bath fan is done to current code. For the record, he came highly recommended to me years ago from XMI Home Inspectors, and he is a senior expert in his field, self-employed as such for 20+ years.

If XMI means AMI, please let me know who this guy is.

My reply was quite long and boring, so here was what I received via e- mail today [:-monkeyd

Buyer's Agent: "Read below - you win. Of course you did. I will need you to let me know if their itemized list of repairs for the siding will do the job, as it looks good to me.

Thanks again, you kick ass."

Listing Agent: "So, my assistant Katlin called Ron about faxing the cited code stuff to him, and apparently he had already called the city and learned that current code would in fact require a correction on his part, so he will be addressing that tomorrow at the property himself."

Thankfully, the code guy he spoke with knew what he was talking about, or this could have been drawn out, with or without all of the supporting documentation.

I like how they specified "current" code -- as if this has changed recently.

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