Bathroom Exhaust Fan Blowing Into Attic

As crazy as it sounds historically most homebuilders have installed that power bathroom exhaust fan in your second story bathroom failing to direct the warm moist air from your bathroom anywhere but in your attic.

Bathroom exhaust fan blowing into attic.

No it s never a good idea to have any exhaust fan in your home dump all that hot moist air in your attic. It may also violate a shingle warranty. Mark the ceiling back in the bathroom measure the inside dimensions of the vent fan s intake port to determine what size hole you need. Most municipalities require extractor and exhaust fans to be vented to the outside of the building with an vent cap.

Several different ways you can move that hot air to the outside. A vent fan evacuates warm and usually very humid air from your bathroom or kitchen you re most often venting steam from a shower or from boiling pots pans. Your bathroom exhaust fan blows directly into your attic. It has the same temperature as the outside which in winter across the northern us will be below freezing.

It seems like such an easy solution just leave a bathroom vent hose in an attic. Use the reference hole as a landmark to transfer your measurements from the attic to the ceiling. It can cause you a lot of problems with mold and mildew forming on the underside of your rafters and decking as well as getting into your insulation. Your attic is an enclosed cold zone.

This will cause mold and could leave your home unlivable. Exhausting of the bath vent fan must indeed be to the building exterior. Dumping bathroom exhaust into an attic or under roof space invites costly mold contamination frost under the roof in freezing climates moisture damage to roof sheathing possibly even plywood delamination or rot roof failures and shorter roof shingle life. No you cannot vent your bathroom exhaust fan into the attic.

Your attic is not a temperature controlled environment is never the same temperature as your living space and generally closer to the temperature outside. It s all outdoor air anyways right. Use a layout square or framing square to draw the. You should never exhaust the bathroom fan directly into the attic.

However you can vent a bathroom fan through an attic while it terminates on the roof or gable end. Exhaust air from toilet rooms and bathrooms shall not discharge into attic crawl space or other areas inside building. So you do need to get that vented outside whether it s through the siding with one of those trap doors that sort of opens out every time you ve got it on or through the soffit. No you should not vent a bathroom fan directly into an attic.

Because what happens is when the insulation gets moist from all that moisture that s being dumped into the attic it completely cuts down on the r value of the insulation.