The team at Feazel encounters bathroom exhaust issues more often than we’d care to admit. Some of the problems we encounter stem from misconceptions about attic ventilation and where the hot, humid bathroom air needs to go. Moisture problems in your attic can lead to major issues. In this blog post, Feazel will let you know the proper exhaust fan ventilation placement is, where not to vent, and more.   

Venting your bathroom exhaust is an easy way to keep your attic healthy and free from mold and mildew.

Reasons Why You Should Never Run an Exhaust Fan to the Attic 

This is the most common venting mistake we find, and it is potentially the most damaging to your home. Your attic moves hot air out and pulls in cool air. Introducing hot and humid air to the attic space creates the perfect conditions to trap excessive moisture in your attic.  

Why is excessive moisture bad? Because it can form mold spores. If you’re lucky, all you’ll have to do is remove mold and have attic mold removal completed. Otherwise, prolonged exposure to hot and humid air can cause your roof sheathing to rot causing roof leaks to form from the inside of your attic instead of the outside.  

Your sheathing is a common building material that is typically made from plywood or OSB. Both products will start to delaminate, buckle and rot with continued exposure to high moisture content.  In short, you should not run your bathroom vent into the attic.

Can I Vent the Exhaust Fan to My Ridge Vent? 

Seems direct, right? It’s a problem because your ridge vent resides near sheathing. There is not a kit to connect your ridge vent to the exhaust ducts so you will be looking at exposing your attic space to additional moisture.  

Where is the Best Place to Vent Bathroom Exhaust Fans? 

There are two superb options to vent bathroom exhaust. The first is through the soffits and the other is directly through the roof. Properly venting your bathroom exhaust fan through the roof is essential for removing moisture from your attic space.  

This is done by re-routing or installing duct pipe from the fan and then routing it to an exterior vent onto the roof giving an exit for moisture. It is important to note that proper exhaust fan ventilation isn't enough on its own. It is imperative that insulated flex hose is used to reduce condensation problems. 

How To Properly Size a Bathroom Exhaust Fan 

The type of bathroom exhaust cfm fan that your home requires is dependent on room size. The square footage of your bathroom can mean that you have different requirements to move the hot and humid air out of your bathroom. Typically, your bathroom exhaust fan should ventilate at least 1 CFM (cubic feet per minute) per square foot of room. An undersized fan will not help move hot and humid air so be sure to size it correctly. 

The minimum sized fan starts at 50 CFM. Larger bathrooms may require multiple exhaust fans to effectively vent your bathroom.  

Be Sure to Vent Your Bathroom Properly 

If you suspect that your ventilation system, or duct system, might not be doing its job correctly, call a professional right away. Letting issues like this go can turn a simple clean up job into a major roof replacement job and cost you thousands of dollars.  

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