This post is one in a series on remodeling small bathrooms as well as one within the sub-series on your options for bathroom remodeling materials. To access either of the lead posts, please select either of the links in the prior sentence.
What can I say about bathroom exhaust fans?
A lot as it turns out. I’ve seen such horrendous damage caused by small amounts of water over long periods of time that I’m almost evangelistic about the benefits of ventilation and the need for bathroom exhaust fans.
The Solera Group provides expert bathroom remodeling services in the greater San Jose metro area
What’s most important to know?
Vent the fan directly to the outside. Although venting the moist air into the attic is better than leaving it in the bathroom, the incremental cost of having a proper roof vent installed is negligible compared to the cost of future water damage, so just do it.
There are fancy vents that allow you to vent through one of the horizontal attic vents (thereby sacrificing one of your attic vents) but they’re terrible. Pay a roofer to do a proper roof penetration vent and be done with it.
How powerful a fan do I need?
I am constantly frustrated by advise to undersize these fans. Remember the Tim Allen character in the Home Improvement TV show who always wanted “more power”. I think he shares my view about bathroom exhaust fans. More power!!!
The general “rule of thumb” is you want 8 air exchanges per hour, or you want your fan to be able to suck all the air out of the bathroom in 7 1/2 minutes.
Please refer back to my comment above about horrendous damage and kindly use that rule of thumb as your starting point.
A standard hall bathroom is 8 feet deep, 5 feet wide, and 8 feet tall. That is 320 cubic feet. At 8 air changes per hour the recommendation is a 40 CFM fan for such a bathroom.
Please consider that the barest minimum. If you find a 200 CFM fan that fits, go for it.
In my ideal work, your bathroom exhaust fan should move air sufficiently fast that when you get out of the shower the mirror isn’t even fogged.
The most powerful fans I’ve encountered are 400 CFM, which I consider entirely appropriate for large master bathrooms.
When it comes to bathroom exhaust fans, more power and faster air changes are better!
For help with your bathroom remodel, please contact us.