Fricking Fan Vents!! How do they work?

fan vents

The purpose of Bathroom fan vents, common problems, and three ways to fix fan vent problems.


What are Bathroom Fan Vents?


What’s the loud thing on your bathroom ceiling that no one turns on?  It’s a fricking Bathroom Fan Vent!  The purpose of bathroom fan vents is to ventilate moisture after hot showers and baths– some people call them ‘fart fans’ but clearing out foul air is secondary to preventing long-term moisture damage.

fricking template

How Fan Vents should be installed.


By code, a window satisfies the ventilation requirement, but we always recommend mechanical fans/vents because who is going to open a window during the Winter??  (Certainly, no one in my family!)  As home inspectors, we look for an active fan vent in every bathroom with a tub or shower (things that produce vapor), which is why we are less concerned about half bathrooms.  During an inspection, we try to verify that these vents exit to the exterior.

When Bathroom Fan Vents go wrong – Moisture!

The mold can get so bad at bathroom ceilings that it can look like a roof leak (see picture).  The damage an improper installation can cause depends on the occupants’ habits.  When bathrooms are rarely or lightly used, it’s less of a concern. However, bathrooms used regularly by several occupants enjoying nice long hot showers will produce a lot of vapor– and where is all that moisture going?  Hopefully, the moisture is vented to the outside, but too often, it’s going into the ceiling or attic, which causes mold/moisture issues over the long term.

mold at bathroom ceiling
Moldy bathroom ceiling

Repairing Bathroom Fan Vents


For almost every category of home improvement, there are ‘good,’ ‘better,’ and ‘best’ repairs. ‘Good’ means ‘not great,’ but sometimes, given a budget or a situation, that’s all that can be done at the time. Good repairs are cheaper, easier to install, and more of a short-term fix.  The best repairs should, in most cases, be installed by a professional– they are costlier but yield the best results over the long term. Below are some ideas for repairs that should be helpful in nearly every situation and budget:

Timers and dehumidifiers (Good)

One idea is to threaten your family repeatedly, like I have, that if they don’t turn on the fan vent during hot showers that the bathroom will be renovated instead of buying family season passes to Dollywood! (good luck with this strategy)

-OR- Install a timer.  Installing a timer is nice, but there is no guarantee that the occupants will turn it on. Timers require ‘enlightened’ occupants; most homes need a foolproof strategy.

-OR- For bathrooms that don’t have a window or a fan vent, or if the fan vent is broken and there isn’t the budget for a professional installation, a small dehumidifier could be purchased.  Remember, it’s only going to dehumidify until the bucket fills up, and then it needs to be emptied.  Also, be sure to keep plug-in appliances away from the plumbing fixtures! This is not a permanent solution.

Combining the fan/light switch or installing a motion sensor (Better)


A simple and effective idea is to combine the fan and light switches- this is a relatively easy project.  This solution forces occupants to use the fan if they want light.   Use a blank face plate or a blank toggle to cover the abandoned switch blank face plate or blank toggle

-OR- This is my favorite, and guests will be impressed with how fancy (and dry!) your bathroom is.  Buy a Motion sensor switch that will turn on the fan automatically whenever anyone walks into the bathroom (make sure that the sensor switch has adequate wattage (600W minimum) for fan/vents.  As long as the sensor works, your bathroom will be ventilated when someone is in it.  If they don’t like to hear the vent when they are just checking their look in the mirror– too bad!

A new high-CFM fan (Best)


Open your checkbook and call a professional to install a powerful 110cfm fan (or higher) with a humidity or motion sensor (Like the Panasonic Whisper Series).  Ask your installer to verify that the fan/vent is vented to the exterior.  This is a quiet and efficient fan/vent- you won’t even notice it working to keep your bathroom dry.

Looking for the exit to a bathroom fan vent
Inspecting a basement fan vent that doesn't exit outside


Bathroom fan vents are intended to prevent moisture damage in your bathroom.  For most people, the cheapest and most convenient option is to combine the light/fan switch or install a motion sensor…  For Do-it-yourself folks, this could cost less than $50! Dollywood, here we come! (or whatever your dream destination may be…)


Thanks for reading, we hope you enjoyed it and look out for similar content coming out soon!

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