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DEAR TIM: I have several inexpensive builder-grade exhaust fans in my home. They are noisy, and I don't feel they do a good job of getting rid of the moist air produced while showering. Is it possible to get high-performance ventilation with little or no noise? I would like a bathroom exhaust fan with a light. Can you tell me how to install a bathroom fan so I do not cause any damage to my home? Faith F., Mt. Crawford, VA
DEAR FAITH: Bathroom fans are a critical part of a home-ventilation system. A bathroom exhaust fan, improperly installed, can create all sorts of hidden damage to a home. All too often, installers just let the moist air escape into an attic space. This moist air can condense on the cooler surfaces in the attic. This liquid water on the wood surfaces creates mold and can lead to serious wood rot.
The good news for you is that the exact fan you are looking for is available. It has been around for years, but many builders choose to install cheaper fans to try to make their houses more affordable. The trouble is, I have discovered many consumers would gladly pay a slight upcharge if they were given the option of having great ventilation and less noise while in the bathroom. It is my hope that builders start to learn to offer home buyers more choices. But I feel that day may never come, as builders will argue that more choices equate to more problems.
These remote bathroom exhaust fans have insulated flexible duct pipe that extends from the fan motor to small exhaust inlet boxes that are attached to the framing members in your bathroom ceiling. The box extends up into your attic, and all you see on the bathroom ceiling is a sleek round inlet cover. The powerful fans can slurp up massive amounts of moist humid air that rises to the ceilings as you shower. This air is ducted through the roof of your home in a special roof vent cap that is easy to install.
I have found that it is often best to vent fans and dryers through the roof. I urge you to watch this video of mine to see how easy it is to install the correct vent-cap flashing on a roof. Have no fear - if done right you will have no leaks.
The flexible insulated ducting that extends from the roof to the fan, and then to your bathroom ceiling, does two important job: It helps to suppress noise from the fan, and the insulation prevents condensation from forming inside the flexible piping. Many people complain about a leaking bathroom fan, when in fact the water is not a roof leak but condensate water that forms inside of uninsulated exhaust piping and flows down the piping into the bathroom.
The bathroom exhaust fans I use come with or without lights. The ones with lights use brilliant compact halogen bulbs that fit into the center of the small circular vent covers. I always place two of these inlets with lights in each bathroom, one immediately adjacent to the shower area and the other toward the center of the bathroom. These lights produce good overall lighting for the average bathroom. You will need additional lighting above any mirror.
To avoid damage to your home while installing a bathroom fan, always follow the written instructions that come with the fan. If you are not comfortable working with high-voltage electric wire so it will pass inspection, then hire a competent electrician to connect the fan. The most important aspect is to duct the air from the bathroom to the exterior of the house. You should do this through the roof.
Avoid the temptation of venting your fan through the horizontal soffit that can be found in many roof overhangs. All too often the moist air billows up under the soffit and is sucked into the attic. If this happens, mildew and wood rot is a certainty.
Problems with bathroom exhaust fans can happen years later. The connections between the flexible duct pipe, the fan, inlet boxes and the roof vent cap must be permanent. Never rely on duct tape to secure these connections. The high heat and humidity in attics can cause duct tape to fail. It is better to use metal band clamps that are nearly identical to traditional automotive radiator hose clamps. These inexpensive clamps can be found at hardware stores, ductwork shops and some home centers. Once the band clamp is connected, then use tape as directed by the fan manufacturer.
Be sure there are no kinks in the flexible duct pipe. Also be sure to install a makeup air duct in your home that allows an equal amount of fresh air to enter your home for every bit of air the exhaust fan is expelling. If you do not have this critical makeup air, you could cause "backdrafting" to occur. This means poisonous gases are drawn into your home through furnace or water heater exhaust pipes.
