Bathroom Exhaust Fans Into Attic

Bathroom ventilation codes require a bathroom exhaust fan to vent to the exterior not the attic for health and structural reasons.

Bathroom exhaust fans into attic.

In all cases the ducting needs to conduct the exchaust to the building exterior and needs to terminate in an animal proof vent cover. Or greater or by mechanical means a bathroom vent fan 20 continuous or 50 cfm intermittent vented to the building exterior. 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. The best exhaust fan venting is through smooth rigid ducts with taped joints and screwed to a special vent hood.

If you have two bathrooms that are close together and one has an exhaust fan and the other doesn t you might be. For optimum performance locate it between the shower and the toilet. The model building codes adopted by most jurisdictions typically require bathroom ventilation to be provided either by an operable window 3 sq. Vent your bath and kitchen exhaust fans through the roof through a special roof hood.

Bathroom ventilation requirements summary. One in line centrifugal fan can be mounted in the attic to exhaust the moisture from two bathrooms. Surprisingly bathroom fans are not required by some building codes. Venting through a roof vent or exhausting them in the attic could cause moisture problems and rot.

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. Each fan vents separately out the roof. All municipalities have different requirements but some do not draw a hard line on requiring exhaust fans. Bathroom code does address the issue of moving odor and moisture laden air from the bathroom to the outside.

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. This article describes routing bath exhaust fan duct upwards through an attic or roof space or downwards through a floor or crawl space. Climb into the attic and clear away any insulation from around the hole. On my home inspections it is still a common sight for me to see bathroom vents going directly into the attic spewing moisture.

Draw a mark on the bathroom ceiling where you d like to install the vent fan. After further inspection it was evident the current home owners vented their bathroom exhaust fans directly into the open attic space and not to the outside. Bathroom exhaust fans perform an important function by removing excess moisture from your home. Use an extra long 3 8 inch diameter spade bit to bore a reference hole through the ceiling and into the attic.