Exhaust Fan Into Roof Space

Same thing with kitchen rangehoods.

Exhaust fan into roof space.

This involves running ductwork from the fan usually though an attic and out through the roof. 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 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. As the air leaves it creates negative pressure behind it sucking in cool air from below into the soffits and creating a self repeating ventilation process.

Hot air exhaust vents located at the peak of the roof allow hot air to escape. No it s never a good idea to have any exhaust fan in your home dump all that hot moist air in your attic. Also some readers have worried that discharging a bath exhaust vent down through a soffit will permit moisture to rise back up into the attic or roof space if the soffit and roof cavity are vented. Certainly it is improper to terminate any exhaust vent directly into an attic or roof space.

No you cannot vent the bathroom exhaust fan into the soffit vents. Having a new house built and have found that the bathroom exhaust fans vent into the ceiling space. It is because of this that many builders tend to advise against this method. In order to accomplish this the roof has to have a hole cut in it.

Several different ways you can move that hot air to the outside. Sometimes there s no choice but to do that especially in terrace homes where space is limited. It may also violate a shingle warranty. If you vent the bathroom exhaust fan to close to the soffit vents which are vented plates under your homes outer edge and roof your home the air can be sucked right back into the attic from the soffit.

Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic.