A bathroom exhaust fan should vent directly outside with its own dedicated duct, for exactly the reasons you are stating.Oct 13, 2010

Can bathroom exhaust fans share same outside duct?

If you have two bathrooms that are close together and one has an exhaust fan and the other doesn’t, you might be wondering if you can tie a new exhaust duct into the existing one. Well, you can’t! You’d often blow air from one bathroom into the other, and local building inspectors wouldn’t approve it.

Where should a bathroom fan be vented to?





Bathroom fans should always be vented to the outside rather than through the ceiling and into your attic. Venting your bathroom fan anywhere other than outside runs the risk of mold forming. Most building codes will require you to vent your bathroom fan to the outside of your house.

Can exhaust fans share a duct?

When the exhaust fan is operating, the back-draft damper is pushed open by airflow to allow air to exit through the exhaust duct. Figure 2. Exhaust fans in separate dwelling units can share a common exhaust if each exhaust fan is equipped with a back-draft damper to prevent cross contamination.

Do bathroom exhaust fans need to be ducted?

Venting to the Outside is Typically Considered Mandatory



One of the main ones is that it brings too much moisture into a space that is meant to be dry. This can get mold started in the insulation, rot roof timbers, and otherwise cause serious problems.

How do you vent a bathroom with no outside access?

Use of a ceiling vent



Installing a ceiling vent is probably the most efficient way to ventilate a bathroom with no outside access. A ceiling vent is a unique machine that allows air to escape from the bathroom. In other words, it’s a machine that, like an open window, allows moisture to escape from your bathroom.

How do you run a bathroom exhaust duct?





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Does a bathroom exhaust fan have to be vented outside?

Bathroom fan installation requires outside ventilation. If the fan isn’t accessible through an attic, you’ll need to vent through a sidewall of your house. These types of ducts and vents are typically installed when the house is built.

Is it better to vent bathroom fan through roof or soffit?

Whether it’s new construction or a remodel, a bathroom vent should always vent through the roof instead of an eave, overhang, or soffit. The point of a bathroom exhaust vent, or any vent really, is to remove hot, moist air from the house.

Can I vent bathroom fan into plumbing vent?

The answer is no way! Sewer gas is explosive and could settle back into your exhaust fan which has an electric motor that is not rated for explosive gases.

How does a ventless bathroom fan work?



Typically, these fans work by processing the air so that they can remove the odors easily and quickly. The fans rely on an activated charcoal filter that is capable of making sure the air is fresh. The filter helps to circulate air throughout the whole room; hence, removing any smell from it.

What is the point of a ductless bathroom fan?

A ductless fan removes excess moisture from the bathroom air by passing air through a filter that draws moisture from the air. This humidity control function is critical to keeping your bathroom fresh and your furniture in tip-top shape.