What Should Humidity Be in a House in Winter?

Your house should have a relative humidity level between 30% and 40% during the winter, according to Energy Star.^[1] Improper indoor humidity levels can not only affect your comfort and health but also damage your walls and flooring.

Low humidity levels during winter months can lead to nosebleeds and chapped lips, whereas high humidity levels during warmer months can cause mold, dust, and allergy issues.^[2]

Here’s what you should know about ideal indoor humidity levels, as well as how to test and control them in your home.

What humidity should your house be in winter?

Energy Star recommends a relative humidity level between 30% and 40% during the winter and between 30% and 50% during the other seasons.^[1] The slightly lower range in the wintertime can help reduce window condensation and mold buildup from heated air.

While there’s a recommended range for the relative humidity level in a home, the right relative humidity level for your home can vary based on multiple factors, including the outdoor temperature, surface, and indoor air temperature, as well as the quality of the insulation in your house.

The Center for Energy and Environment recommends that homeowners set humidity levels based on the following outdoor temperatures:

• −20 degrees or below: <15%

• −20 to −10 degrees: <20%

• −10 to 0 degrees: <25%

• 0 to 10 degrees: <30%

• 10 to 20 degrees: <35%

• 20 to 40 degrees: <40%^[3]

Read More: How to Winterize a House

What is relative humidity?

There are two types of humidity: absolute and relative. Absolute humidity is expressed in grams and shows the amount of water vapor in the air. Absolute humidity doesn’t consider air temperature, however. Relative humidity, represented as a percentage, measures the amount of water vapor in the air relative to the air temperature.

Cold air can hold less water vapor than warm air, so a warm day would have a lower relative humidity than a cold day, even if the number of water particles in the air is the same. You’ll want to lower the humidity in your home to prevent potential adverse effects.^[4]

Effects of high humidity

If your home is too humid, you could expose your property and your family to adverse effects, such as:

Condensation on windows

Water buildup on your windows can cause more problems than you may think. Repeated condensation on windows and frames can deteriorate seals and make them less energy efficient. Additionally, too much condensation can freeze if temperatures drop, and frozen glass is liable to break.

Condensation on walls

Condensation on your walls can foster bacteria and mold growth, especially when combined with heated air. Mold in the air can also irritate allergies and create an unhealthy living environment if left untreated.

Damage to property

High humidity levels can damage wood, art, and other personal belongings. In addition, long-term exposure to high humidity levels can slowly destroy the structure of your home, including the foundation and walls.

Check Out: Does Homeowners Insurance Cover Water Damage?

Effects of low humidity

Too little water in the air can also cause problems, especially regarding comfort and health in your home. Some common effects of low humidity in a home include:

Dry skin and nasal passages

Too little water in the air can cause dry, cracked skin, and dry nasal passages. People prone to nosebleeds could have them more frequently. Additionally, too little humidity can cause a scratchy throat and itchy eyes. People with asthma may find it especially difficult to breathe in less humid homes.^[5]

Feeling colder

Lower humidity levels can cause people in your home to feel chilled or cold, even when the thermometer is high, since low humidity allows heat to escape your body more quickly. In contrast, your body takes longer to release heat in high-humidity settings. Low relative humidity in your home could also result in higher energy bills.

Damage to belongings

The correct humidity level is essential when protecting important documents, artwork, and furniture in your home. Artwork can become more fragile when exposed to too little humidity over time. Additionally, your wood furniture needs some moisture to avoid cracking. Low humidity can also cause cracked paint and shrunken or warped wood floors.

Learn More: What Does Home Insurance Cover and What Does It Exclude?

How to test room humidity

The most straightforward way to test the moisture in your home is to purchase a hygrometer. You can buy one from most major stores for less than $10. A digital hygrometer will tell you the humidity levels in easy-to-read numbers.

You should install it five feet above the floor and away from direct sunlight and humidifiers. It can take a hygrometer several minutes to produce an accurate result. Check the numbers at least weekly to ensure optimal humidity levels.

How to control humidity in your home

You can control how much humidity you have in your home in many ways, including: 

Use a humidifier

A humidifier introduces water into the air with water vapor or steam.^[5] You can purchase cool or warm mist models that sit on a flat surface and introduce humidity to one room. Some brands even offer whole-house humidifiers, but these are typically more expensive and offer less control from room to room.

You can also control humidity levels in multiple rooms if your HVAC system has a humidifier. These are also typically more expensive than a standard HVAC system, though. A more cost-effective option is to purchase multiple humidifiers that you can place in individual rooms to adjust their humidity levels.

Use a dehumidifier

Dehumidifiers control humidity levels in a room by removing excess water from the air to maintain a set relative humidity level. They help prevent mold, mildew, and damp air. People often use dehumidifiers in areas where the relative humidity regularly exceeds 60%.^[6]

Take steps to control moisture in your home

Some simple things you can do to control how much moisture is in the air in your home include using a fan in your bathroom when taking hot showers, fixing leaks and water seepages quickly, covering dirt floors in crawl spaces with a plastic tarp, and improving the insulation in your home with better windows.^[7]

Humidity in a house in winter FAQs

Here are answers to some commonly asked questions about humidity and your home.