Know Your Ventilation

Good home ventilation is critical to comfort and safety. It protects a home’s occupants from unpleasant odors, irritating pollutants and potentially dangerous gases like carbon monoxide and radon.

Well-planned ventilation also prevents the growth of mold and mildew, which can cause or aggravate allergic reactions and lung problems such as asthma.

Whether you are building a new home or want your existing home to be better ventilated, the following information can help.

Ventilation Basics

First, it is important to understand the basics of ventilation. There are two basic ways to ventilate home.

  • Spot ventilation uses exhaust fans to collect and remove moisture, odors and pollutants before they spread throughout your home. An exhaust fan is generally turned on only when moisture, odors or pollutants are being produced. That is why they are most likely to be used in bathrooms, kitchens and laundry rooms.Spot ventilation may also be appropriate for workout rooms or workshops. Rooms used for crafts or hobbies that produce air contaminants should also be separately ventilated to ensure that the contaminants do not mix with the general house air.
  • General ventilation fans run all the time to control pollutants from sources that cannot be spot ventilated. For example, carpets, furniture and drapes, all of which are constantly releasing fabric fibers and gases such as formaldehyde, are usually found throughout large areas of a home.

Exhaust-only General Ventilation

One of the ways to handle general ventilation is through an exhaust-only system. This entails using exhaust fans to pull stale air out of a home while drawing fresh air in through cracks, windows or fresh air intakes.

Exhaust-only ventilation is a good choice for homes that do not have existing ductwork to distribute heated or cooled air. However, if there is radon in the soil around the house, this method can increase indoor radon levels so make sure to have radon levels tested regularly.

A Room-by-Room Guide to Ventilation


Among the main places in a home that require ventilation are the bathrooms. These spaces are notorious for excess humidity and odors. Improperly managed moisture can lead to mold, creating health concerns and damaging expensive-to-repair finishes.

Make sure to operate the bathroom exhaust fan any time a bathroom is in use, particularly during showering and bathing. Operate the exhaust fan for up to 60 minutes after finishing a bath or shower to remove most of the moisture in the room.

There are many product options that can meet help control bathroom moisture and odors.

Surface-mounted fans are available in wide ranges of prices and performance levels. Look for products today that operate quietly, use little energy and still provide powerful ventilation. Fans approved for installation in showers and steam rooms exhaust moisture very effectively. In addition, humidity-based controls can provide automatic operation, and timers ensure that ventilation continues long enough to reduce moisture levels.

Inline fans are generally installed remotely, often in attics and basements. This helps keep any fan noise at a minimum in the occupied areas of a home. One fan can be used to ventilate two or more bathrooms through a common exterior exhaust hood. A variety of exhaust grilles is available. Some even have lights incorporated. Inline fans are a good choice when the duct runs to the outside of the home are long, as they are better able to maintain airflow.

Controls installed in a bathroom allow the continuous ventilation rate to be increased when needed to remove excess moisture and odors. The combination of continuous and intermittent ventilation ensures that bathrooms remain dry and fresh.

Laundry rooms

Dryers generate heat and moisture, ideal conditions for mold growth on ceilings and walls. Proper dryer ventilation is of paramount importance. While opening a window can help, installing an exhaust fan in the laundry room will be far more effective in eliminating moisture. Clothes dryers should also be exhausted directly to the outside, and filters and hoods cleaned regularly to maintain maximum airflow.


Fresh air is important for relaxation, and there is no better place to relax than in the bedroom. However, it is not always practical to keep windows open so fresh air can circulate through the room. Exhaust and supply fans that distribute fresh air are good options for ensuring better air quality.

Other Rooms

Other rooms of the house may require local ventilation to address periodic high levels of contaminants resulting from various hobbies or increased activity levels among a home’s occupants. Consider rooms used for arts and crafts where paint and other supplies could potentially create toxic fumes if confined to a small space.

Rooms used for strenuous exercise can also collect odors and moisture, as can spaces where pets are confined while their owners are away. Both spot and general ventilation options should be considered in these spaces.


Attached garages are obvious sources of pollution, from unhealthy odors from cars and lawn chemicals to deadly carbon monoxide. The shared walls between the living area and garage are typically sealed to minimize the entry of contaminants through infiltration. However, when the entry door between the garage and house is open, there is a risk that contaminants may enter. An exhaust fan activated when the garage door is opened will help ensure that extra pollutants generated when a car enters or leaves does not enter the home.

What You Can Do

In addition to ensuring proper ventilation throughout a home, you can improve indoor air quality by removing or avoiding common sources of moisture, odors and gases. For example, do not store firewood in the house. After taking out the garbage, wash the can. Use mild cleaners or water-based paints to avoid chemical odors.

Clean any surface mold and mildew you find. Be aware that some molds can be dangerous when released, so read and follow the instructions on any products you use for mold and mildew removal.

For More Information

To learn more about ensuring proper ventilation in your home, contact a contractor who specializes in residential heating and ventilation. Or see a kitchen and bath specialist at your local hardware or building supply retailer.

For specific ventilation product information, visit the Products & Services section on this web site.