Bathroom Exhaust Fans Into Attic

On my home inspections it is still a common sight for me to see bathroom vents going directly into the attic spewing moisture.

Bathroom exhaust fans into attic.

Bathroom code does address the issue of moving odor and moisture laden air from the bathroom to the outside. Bathroom ventilation fan duct routing routing a bath vent duct down out or up through an attic or roof out. The model building codes adopted by most jurisdictions typically require bathroom ventilation to be provided either by an operable window 3 sq. When venting a bathroom exhaust fan make sure to vent the air to the outside rather than into your attic where it can cause mold and mildew to form.

The problem with this approach is that all of the moisture in the air goes onto the wood sheathing insulation wood rafters and wood ceiling joists which can lead to mold growth and rot. When we got into the attic i quickly noticed the smell moisture and what i could see as mold on the roof rafters above each bathroom. For optimum performance locate it between the shower and the toilet. One in line centrifugal fan can be mounted in the attic to exhaust the moisture from two bathrooms.

Bathroom ventilation requirements summary. Draw a mark on the bathroom ceiling where you d like to install the vent fan. Bathroom exhaust fans perform an important function by removing excess moisture from your home. In all cases the ducting needs to conduct the exchaust to the building exterior and needs to terminate in an animal proof vent cover.

Each fan vents separately out the roof. This article describes routing bath exhaust fan duct upwards through an attic or roof space or downwards through a floor or crawl space. All municipalities have different requirements but some do not draw a hard line on requiring exhaust fans. Vent your bath and kitchen exhaust fans through the roof through a special roof hood.

Climb into the attic and clear away any insulation from around the hole. Or greater or by mechanical means a bathroom vent fan 20 continuous or 50 cfm intermittent vented to the building exterior. Each bathroom has its own exhaust fan. The best exhaust fan venting is through smooth rigid ducts with taped joints and screwed to a special vent hood.

Surprisingly bathroom fans are not required by some building codes. Bathroom ventilation codes require a bathroom exhaust fan to vent to the exterior not the attic for health and structural reasons. Venting through a roof vent or exhausting them in the attic could cause moisture problems and rot. If you have two bathrooms that are close together and one has an exhaust fan and the other doesn t you might be.