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Bathroom exhaust vent fans

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Hi guys,

I live in Baton Rouge, Louisiana. I just bought a house recently. Before I bought a house, I hired an inspector to check the house upside down. Unfortunately, he missed spots that all four bathroom exhaust vent fans did not exit out the proof. Instead, all of them freely flow right on fiberglass installation in attic. I can see mold and mildew around the area of exhaust vents. Is that against of LA State Regulation? If the inspector found the problem before I bought a house, I can ask the owner to pay for the installation.

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While I am not up to speed on the LA State regs, and without knowing whether the attic cavity was accessible for the inspector, the simple answer is yes, the bathroom vent(s) should be routed to the exterior of the home. Did the inspectors report state that he went into the attic? Have you contacted the inspector?

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IRC requires that mechanical exhaust vents (bathroom, utility room, etc.) be routed to exterior envelope of the home (through roof or sidewall, etc.).

NOT dumped into soffit vent (eave) area or left into attic space.

Local AHJ's may or may not strictly enforce such during time of home's construction.

Your situation of mildew and such is common when the exhausts are vented into the soffit/eaves as that is actually an "air intake" for attic circulation. Ergo the "intake" air is blowing the humid air from the mechanical vent back into the attic space. Moisture/dampness over time allows mold/mildew to grow.

Marc (inspector in LA) can likely add more granular detail to this for the local requirements.

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Dear Rob,

Thank you for your response. I have looked the inspector's report. He went to the attic and checked two water heaters, chimmey, wind turbines and the electric attic fan, but not any vent(s). He even missed the kitchen ventilation. The air duck pipe hung on the inner roof. I just bought a new duct pipe long enough to get it connected to the outside. I will call the inspector tomorrow. In the mean time, I may check out the dryer vent, too.

Thank you,


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Thanks Nolan.

Thamlang, The bath vents that discharge into the attic space is a common condition here (I'm from Lafayette). It's usually not a problematic issue in this climate, unless your attic is very low and does not have adequate ventilation. It IS a major issue up in northern USA where attic temperatures might get below the dew point in the winter season if too much moisture is dumped or leaks into the attic space. The codes do require that the bath vents discharge to the exterior but a home inspection is not a code inspection.

As for the mold, if it was there and visible on the day of the inspection, it should have been reported to you. That is assuming that the inspector did indeed enter the attic. The Standards of Practice, of which you should have received a copy from the inspector before the inspection, allows the inspector to refuse to enter the attic if he considers the access to be inadequate of if he considers the attic space unsafe to enter. If he does not enter the attic, he is required to report that fact to you and the reason why he did not enter it. Some inspectors will not enter ANY attic, citing 'safety' concerns.

If the ceiling drywall is exposed where the bath exhaust has blown it out of the way, I would have mentioned it myself but the Standards of Practice of Louisiana only requires, among other things, mention of the presence, or absence, of attic insulation. If the area of exposed ceiling drywall does not evidence the presence of a vapor barrier, then that fact should have been reported to you also. It is required by the Standards of Practice although it too, is not an issue in this climate.

Let me know if I have not answered your questions to your satisfaction.


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