Exhaust Into Attic

No you cannot vent your bathroom exhaust fan into the attic.

Exhaust into attic. 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. 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. Duct already wrapped in insulation at home centers. Venting into the attic sends excess moisture to that space which can cause mold and other problems.

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. It may also violate a shingle warranty. Although this isn t always possible in attic crawl spaces you should always insulate the duct to prevent condensation problems. Your attic is not a temperature controlled environment is never the same temperature as your living space and generally closer to the temperature outside.

You should never exhaust the bathroom fan directly into the attic. Intake vents located at the lowest part of the roof under the eaves allow cool. You can find 4 in. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.