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I just found out that our bathroom exhaust fan has no duct attached to it. Our current fan is Panasonic FV-08VQ2 (90 CFM, 4" duct diameter). The fan just blows the air to the inaccessible attic. There is what looks like an attic exhaust close to the location of the fan but no duct (see white circle in the picture). The bathroom exhaust fan is about 5' from the window on the top floor. Here are my questions:

  1. Is this a big problem? I assume the fan has been like this for 15+ years. If it is, I will look into getting a duct there, which is complicated by the inaccessible attic space.

  2. Should we stop using the fan until this gets fixed?

  3. Should we be concerned about any mold etc in the attic as a consequence of this?

Thanks!

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    The easiest thing to do is go up into the attic. If it is clean as a whistle, it is of no concern until someone makes you meet code to sell house or do a reno.
    – DMoore
    Commented Apr 6, 2020 at 5:51
  • I notice there are no soffit ventilation holes. But perhaps the gables at either end of the house have large vents in them. If the attic is very drafty, it is less likely that there is significant mold and moisture damage.
    – Ray Butterworth
    Commented Apr 8, 2020 at 15:16
  • Where is the house? In particular does it experience cold winters? When there is snow on the roof, moisture condensation is much more likely.
    – Ray Butterworth
    Commented Apr 8, 2020 at 15:18
  • @DMoore "The easiest thing to do is go up into the attic." - although the OP has stated that the attic is "inaccessible"? Maybe the "easiest" way might be to climb a ladder and open the vent?!
    – MrWhite
    Commented Apr 8, 2020 at 15:30

5 Answers 5

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Is this a big problem? I assume the fan has been like this for 15+ > years. If it is, I will look into getting a duct there, which is complicated by the inaccessible attic space.

Moisture in the attic is a problem and the fan needs to be ducted to the exterior. I find it hard to believe that your attic has no access. Code requires one for many reasons including maintenance and for fire fighting.

Should we stop using the fan until this gets fixed?

After 15 years, a little longer won't be a big difference in the overall picture and not using it can cause problems in your bathroom due to excessive moisture there.

Should we be concerned about any mold etc in the attic as a consequence of this?

Yes. When you get the work done have them check for mold and decay of the roof framing members and roof sheathing

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    They might be able to remove the fan and remove the outside grill and fish a duct in there. It's pretty high up so much care should be taken.+
    – JACK
    Commented Apr 5, 2020 at 21:51
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    How would an attic be required to have access? A cape cod can have many different sections of attic. Mine has 8, not a single one has access.
    – rtaft
    Commented Apr 6, 2020 at 14:27
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    In the International Building Code (and others). IBC R807.1 Attic access. "Buildings with combustible ceiling or roof construction shall have an attic access opening to attic areas that exceed 30 square feet (2.8 m2) and have a vertical height of 30 inches (762 mm) or more. The rough-framed opening shall not be less than 22 inches by 30 inches (559 mm by 762 mm) and shall be located in a hallway or other readily accessible location. ... A 30-inch (762 mm) minimum unobstructed headroom in the attic space shall be provided at some point above the access opening"
    – Ack
    Commented Apr 6, 2020 at 14:49
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    Thanks @Ack! Very helpful. The building is from ~1860 and I don't think they had the attic requirements back then. I searched everywhere and there really is no access.
    – user2503795
    Commented Apr 6, 2020 at 19:10
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    You're very welcome user2503795. I'm not too surprised as the codes are relatively new and being refined all the time. BTW, your house is surely grandfathered in so as long as you don't do renovation then you don't need to update with an access. But when you do related work they will probably require it during the permitting phase. JACKs solution is a very good one, you can probably do the work from the bathroom and outside existing opening.
    – Ack
    Commented Apr 6, 2020 at 19:26
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Ack's answer is very good, so I won't repeat what they wrote.

I will add that molds can definitely create a significant health hazard.

I would get the attic inspected for the presence of hazardous levels of molds.

From personal experience, I can tell you that mold inside walls and attics can be extremely hazardous to your health. It doesn't have to be visible within the rooms of your home. Having mold inside walls, attics, or crawl spaces is more than sufficient to cause years of serious health problems and needless suffering.

Add effective ducting and test for mold.

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Venting into an attic is terrible in North American climate zones (6,7,8 in linked map below); less so in arid southern zones (1,2). This will give you a sense of how bad this might be. Beyond that, what @ack said.

Map: zone map

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As already stated this is bad for your attic and underside of roof, when you do install ducting make sure it is insulated.

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New exhaust vent shall be located at least 4 feet from a window opening as per nsbc. Unless your unit has a sprinkler system. I would redirect through the roof with a duraflo exhaust vent.

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  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know the details of contributing here.
    – Daniel Griscom
    Commented Apr 7, 2020 at 17:05
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    Out of curiosity, what is the relationship between a sprinkler system and the bathroom fan exhaust?
    – JimmyJames
    Commented Apr 7, 2020 at 17:53

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