Bathroom Exhaust Fans Into Attic

Bathroom ventilation requirements summary.

Bathroom exhaust fans into attic.

One in line centrifugal fan can be mounted in the attic to exhaust the moisture from two bathrooms. Each bathroom has its own exhaust fan. Or greater or by mechanical means a bathroom vent fan 20 continuous or 50 cfm intermittent vented to the building exterior. Use an extra long 3 8 inch diameter spade bit to bore a reference hole through the ceiling and into the attic.

Venting through a roof vent or exhausting them in the attic could cause moisture problems and rot. Bathroom code does address the issue of moving odor and moisture laden air from the bathroom to the outside. 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. Bathroom exhaust fans perform an important function by removing excess moisture from your home.

The best exhaust fan venting is through smooth rigid ducts with taped joints and screwed to a special vent hood. On my home inspections it is still a common sight for me to see bathroom vents going directly into the attic spewing moisture. If you have two bathrooms that are close together and one has an exhaust fan and the other doesn t you might be. This article describes routing bath exhaust fan duct upwards through an attic or roof space or downwards through a floor or crawl space.

Vent your bath and kitchen exhaust fans through the roof through a special roof hood. In all cases the ducting needs to conduct the exchaust to the building exterior and needs to terminate in an animal proof vent cover. 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. Climb into the attic and clear away any insulation from around the hole.

Each fan vents separately out the roof. 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. Bathroom fan vent code requirements include no venting to attic areas to help reduce mold or structural problems.

All municipalities have different requirements but some do not draw a hard line on requiring exhaust fans. 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. Draw a mark on the bathroom ceiling where you d like to install the vent fan. For optimum performance locate it between the shower and the toilet.