Type of Venting Bathroom Exhaust Fans
Vertical Wall Installation
The most common bathroom venting option is when the exhaust fan is installed in the ceiling or wall, and the vent goes to a nearby exterior wall. This option usually requires the shortest vent and is less vulnerable to water intrusion than a roof vent. However, it requires a hole in the exterior wall and running a duct through ceiling joists. A vent hood is installed on the exterior wall which includes a flapper and possibly a screen to keep out pests and prevent air or water infiltration.
Venting your bathroom fan directly to the roof is another common option. A special metal roof vent is installed that keeps out rain and animals. The roof vent needs to be very durable to withstand the exterior weather. The downside of venting to the roof is that there will be a possibility of future leaking. However, this shouldn’t stop homeowners from venting to the roof since it is an extremely common installation.
If your bathroom is on the uppermost level of the home, installing the vent through the attic and to the gable is very common. The gable is the triangular portion of the exterior wall which is in-between your roof pitches. Since you have access to the attic, it can make the installation significantly easier. However, it is recommended to install an insulated duct to prevent condensation from forming inside the vent.
The exterior wall is another common option for venting a bathroom exhaust fan. This option is similar to the vertical wall installation, but the vent is directed to an exterior wall. This option also requires a hole in the exterior wall and the installation of a vent hood to keep out pests and prevent air or water infiltration.
Common Ventilation Issues: Bird and Insect Nests
One common downside of venting a bath fan to the exterior wall or gable is that it is vulnerable to animal intrusion. Birds typically cause the most problems with vents because they love to nest inside bathroom (and dryer) vents. The nest can completely obstruct air flow which will make the bathroom exhaust fan more or less ineffective. Homeowners need to make sure that the exterior vent cover has a pest screen and flapper to keep birds out.
The Importance of Airtightness of the Ventilation System
Airtightness is crucial in a ventilation system to prevent air leaks and maintain the efficiency of the system. Air leaks can lead to energy loss and increased utility bills. Moreover, they can also allow the entry of pollutants and allergens into the home, affecting the indoor air quality. Therefore, it’s essential to ensure that the ventilation system, including the bathroom exhaust fan and its venting, is airtight.
Soffit Installation: A Less Common Approach
Soffit installation is one of the least common bathroom exhaust fan venting installations. The soffit is the underside of your roof overhang, and there is usually a type of passive venting installed there called soffit venting. However, this method is not recommended because it can cause mold problems in the attic if there is existing soffit ventilation.
Attic Termination: Not Recommended
Attic termination is another method where bathroom vents terminate in the attic. However, this method is not recommended as it can lead to mold growth, reduced indoor air quality, and potential moisture damage to ceiling joists, rafters, and sheathing.
Insulating Your Bathroom Fan Duct
Insulating the duct hose as it goes through the attic area (or any unconditioned part of the house) is a commonly overlooked consideration. If the attic air is very hot, and the bathroom air getting exhausted is cold, then these temperature differences may cause water to bead on the outside or inside of the vent and ultimately cause moisture damage or mold.
Avoiding Bird Nests in Your Venting System
As mentioned earlier, birds typically cause the most problems with vents because they love to nest inside bathroom (and dryer) vents. The nest can completely obstruct air flow which will make the bathroom exhaust fan more or less ineffective. Homeowners need to make sure that the exterior vent cover has a pest screen and flapper to keep birds out.