Indoor Humidity Guide: How to Manage Your Home's Humidity

When people think about the comfort of their homes, they often focus on temperature instead of humidity. However, humidity plays a significant role in how people experience temperature, and it has other effects as well. Humidity that is too high or low can cause problems in the home and health issues for the people living in it. Controlling the humidity is an integral part of the home's heating, cooling, and ventilation management. Read on to learn how to identify indoor humidity problems and create a plan to solve them.

What Is Relative Humidity?

Humidity is the amount of water vapor in the air. Most people think of humidity in terms of a percentage. This percentage is known as relative humidity because it is estimated relative to the maximum amount of humidity possible at any given temperature. Relative humidity affects the way that people feel indoor and outdoor temperatures, especially heat. On a hot day, high humidity can make people think that the temperature is even hotter than it is. Humidity affects people's ability to cool down by sweating, which is why high humidity can be difficult to manage or even dangerous.

What Is the Ideal Home Humidity?

In most cases, the ideal relative humidity for a home is 30 to 50 percent. Humidity rates higher than 50 percent can trigger mold growth because the ventilation systems in the home may not be able to evaporate it quickly enough. Humidity rates below 30 percent also present a problem that requires a solution. Very low humidity can cause health problems for people and structural damage to the home. HVAC systems are designed to help maintain an ideal relative humidity range, but proper sizing, installation, and use are key. Homeowners may need to augment the system in some cases.

How to Monitor Home Humidity

There are ways that homeowners can determine if the humidity level is a problem, but they may need a sensor to determine the extent of the problem. Homeowners can buy smart thermostats that contain a sensor to measure and report relative humidity. These tools cost between $50 and $200, and they are designed to control the home's HVAC system as well. Otherwise, people may consider buying a humidistat or hygrometer for $10 to $20. These are small devices intended to measure humidity, which can be placed almost anywhere in the home. Homeowners can buy these products online or at home improvement stores.

Why Is My House So Humid?

When homeowners begin to suspect that their homes have too much humidity, they should start by exploring the possible causes. In most cases, high humidity is affected by some combination of high humidity already present in the region's climate, plus an inability of the home's existing systems to manage it. Ideally, air conditioning systems exist to extract humidity from the indoor air. However, if the system is too large for the home, it may cool the temperatures and shut off before removing enough moisture.

In some cases, the presence of humidity is a larger problem that homeowners have to manage. Regions with high humidity will naturally have homes with higher humidity, absent some form of moisture management. Additionally, people who live in areas with a lot of groundwater may notice that it seeps in through cracks in the foundation, spreading to the walls. Even running a lot of baths or showers, or cooking often in the kitchen, can lead to higher relative humidity levels in these rooms. Insufficient ventilation, or a failure to use it effectively, could make these problems worse.

Signs of Too-High Humidity

There are a few signs that the humidity is too high:

• Condensation buildup on windows and walls
• Musty, mildewy, or moldy odors
• Rooms that feel hot and muggy
• Fog on window panes, independent of outside temperatures
• Higher incidence of allergies
• Moldy or rotting wood

How High Humidity Affects Your Health

Although high humidity may seem like largely an issue of comfort or structural integrity for the home, it presents a number of health concerns as well. People should watch out for the following as indicators that they may need to find a better way to manage their home's humidity:

• Regular problems with dehydration, even in cooler temperatures
• Dizziness, weakness, or other signs of heat exhaustion
• Skin problems, such as dermatitis or eczema
• New diagnosis of asthma, or difficulty managing an existing condition
• Congestion or cold-like symptoms
• Difficulty sleeping

One reason that high humidity often contributes to a greater incidence of allergies and asthma is the way that it affects indoor air quality. Due to imperfect ventilation, indoor air quality is often worse than the air outdoors. Homeowners do not use ventilation effectively, contaminants can create more issues. Humidity often causes products with high levels of VOCs to off-gas more readily, releasing pollutants that can make people feel sick, stuffy, or lightheaded. Although managing moisture in the home may not immediately solve all of these problems, it is relatively simple and can help rule out other possible causes.

Effects of High Humidity on Your House

High humidity can have severe effects on the home, even if they do not become apparent immediately. In many cases, moisture takes time to accumulate, and homeowners may not be aware of it because much of the damage occurs in places that are difficult to see. Much like other types of water damage, humidity can be devastating to a structure. Common problems include:

• Accumulation of mold or mildew behind the walls
• Rotting wood, especially in the house's framing
• Swelling and contracting of the structure, which could lead to cracks and sinking
• Damaged belongings, particularly furniture and flooring
• Cracked or peeling paint and wallpaper
• Pest infestations that are difficult to prevent or remove

For short periods of time, the accumulation of moisture in the structure may be relatively simple to fix. Over time, water damage can require repairing or replacing significant parts of the home. For example, a foundation that contracts and breaks due to high humidity makes leaks from underground more likely. People may notice a higher incidence of mold or basement flooding as a result.

How to Decrease a Home's Humidity in Summer

For most homeowners, decreasing humidity in the summer is the most important task. By using a variety of methods, including dehumidifiers and other approaches, homeowners may notice an improvement in their electricity bills as well.

Portable and Whole-House Dehumidifiers

One of the simplest and most practical solutions to removing moisture from the home is to purchase and install a dehumidifier. Homeowners can choose between portable models and products that are designed to work with a central HVAC system. Simply put, a dehumidifier extracts moisture from the air surrounding it. In most cases, it has a collection unit for condensation that users can empty on a regular basis.

When using these systems, users should ensure that it has the proper amount of airflow on all sides and operate it in an area that is generally clean and free of debris. Whole-home dehumidifiers operate in a similar way, but they are designed to turn on and off automatically to go with the HVAC system. They may also have a built-in drainage system so that users do not have to remove the condensation manually.

How to Reduce Humidity Naturally Without a Dehumidifier

Although some homes may require a dehumidifier to maintain a proper humidity level, it is not always necessary. Homeowners may want to try other methods first, particularly if they have a modern HVAC system. Air conditioners were originally invented to control humidity, not temperature. The positive effect on temperature was a beneficial side effect. As a general rule, air conditioners and heat pumps remove moisture and recycle the conditioned air back through the home. Proper sizing is essential. A unit that is too large cannot extract enough water before turning off at a lower temperature. As such, homeowners should aim to install a unit that matches their home's cooling load.

Even without an air conditioner, people can still lower the home's humidity level. The use of desiccants is a very popular method of controlling a room's humidity level. Regular use of exhaust fans in the kitchen, bathrooms, and laundry room can vent the excess moisture produced from activities in these rooms. Sealing air leaks around the structure and fixing cracks in the basement can prevent moisture from getting in. Similarly, homeowners may want to consider cleaning out their gutters and ensuring that the downspouts point away from the home. Proper grading of the property also helps to ensure that outdoor precipitation does not turn into indoor moisture. Installing and maintaining a sump pump can minimize the damage from storms and prevent moisture accumulation in the basement.

How to Control Indoor Condensation

Cool surfaces in a warm room lead to condensation, which can increase the humidity. Homeowners can manage this by reducing the likelihood of condensation collecting on surfaces inside the home. There are several methods that can help, including:

• Insulating cool-water pipes in the plumbing
• Installing new windows with multiple panes and air between to reduce condensation from temperature differences outside
• Installing storm doors and windows to keep precipitation out
• Adding caulking and weatherstripping to doors and windows

Covering pots while cooking and promptly cleaning up spills can also decrease moisture production and the resulting condensation.

What Causes Low Humidity?

Some regions are drier than others, which calls for a different type of humidity management. The changing seasons often affect relative humidity. In most cases, winter is associated with lower levels of humidity. When the air is colder, it is less able to retain moisture. As such, water naturally present in the air is more likely to show up as condensation rather than humidity. People living in regions that have dry winters, or dry months in autumn or spring, may notice the effects of low humidity the most.

In addition, the use of heating systems affects humidity levels inside the home. Central, forced-air heating is a common cause of dry air in the home. Systems that rely on combustion tend to burn up the excess moisture in the air as part of the process for creating heat. The continuous cycling of air throughout the home, as a major function of the HVAC system, ensures that the air maintains a relatively consistent humidity in all rooms of the house. Although other types of heating that rely on combustion can cause the same problems, they may be focused in one room instead of the entire home.

Signs of Too-Low Humidity

Low humidity causes a variety of problems, including:

• Chips in the interior paint
• Wood that splits or cracks as it dries in flooring, furniture, and millwork
• Static electricity, commonly present near carpets and other soft surfaces
• Health issues related to dry air

How Low Humidity Affects Your Health

For most people, low humidity manifests as cold-like symptoms. Mucous membranes are intended to remain relatively moist, which is more difficult to manage in an area with exceptionally dry air. It is common to notice sore sinuses or a bloody nose after spending time on an airplane or in a hospital, for example, because these places maintain low humidity levels by design. Similarly, when living in a home with low humidity, people can suffer from the following concerns:

• Dry skin
• Itchy or dry eyes
• Sinuses that feel dry or tight
• Increased sneezing
• Chapped lips
• Dry mouth or throat

Over time, these problems can cause those mucous membranes to become inflamed as a result of the dryness. Swollen sinuses are a common cause of chronic headaches. In some cases, the dry air makes it easier for infectious diseases to spread. Someone sneezes, the air droplets dry out, and the virus moves in an aerosol form. People who notice these problems may want to consider adding humidity to the home through different methods.

Effects of Low Humidity on Your House

Low humidity can also cause damage to various parts of the home. Most components in a structure are designed to handle moderate humidity. Too much or too little can change their composition, which affects how they can support the house. Wood shows one of the most common and visible effects of low humidity. As the natural moisture in the wood evaporates, each piece may contract to accommodate a smaller mass. Wood flooring that has been nailed down could split at the side of the nail. People may notice gaps between boards or small cracks that grow larger. The effect is similar for things like paint and wallpaper, although they tend to be less severe.

Low humidity also prompts people to make different decisions in the way that they heat their homes. Air with low moisture content tends to feel cooler. As a result, people may notice that dry air in the home makes them more likely to turn on the heat as a way to warm up. Unfortunately, most heating methods also contribute to low humidity. This process can become a repeating cycle where people feel the effects of low humidity and then take actions that decrease humidity even further.

How to Deal With Low Humidity in Winter

Dealing with low humidity in winter offers numerous benefits. Besides providing better protection for the structure and the health of people living in the home, maintaining an ideal humidity can also lower utility bills.

Portable and Whole-House Humidifiers

Humidifiers use a fan to turn water into vapor that can add humidity to the air. Portable humidifiers are available online and in a variety of stores for $20 or more, depending on the size and features. These devices are easy to use and ideal for increasing humidity in a specific room. Humidifiers come in cool and warm mist varieties, depending on the room and the need to protect residents from steam heat. Users must clean out the reservoir regularly to prevent the buildup of mold or other contaminants.

Homeowners should take care to avoid using a humidifier that is sized improperly for the space. Humidifiers that add too much moisture can lead to accumulation on the walls or other issues related to condensation. New humidifier users may want to start with a smaller model or consider hiring a professional to install a whole-house humidifier that is the right size.

How to Increase Humidity Without Buying a Humidifier

Although buying and using a humidifier is usually the easiest way for people to increase low humidity in the home, there are alternatives. Anything that turns water into water vapor can increase the humidity, even if it is limited to a particular room. For example, homeowners who are trying to raise the relative humidity may want to try the following:

• Boiling pots of water on the stove
• Opening the bathroom door while taking a shower or bath
• Leaving hot water in a bathtub for a few minutes after bathing
• Adding indoor plants, especially those that require regular watering
• Placing bowls of water on a windowsill to evaporate in the sun

Allowing clothes to air dry instead of running them in the dryer can increase humidity while simultaneously decreasing the effects of a dryer that relies on combustion to produce heat.

In winter, one of the best things that people can do to improve low humidity is to keep careful control of the thermostat. Running a forced-air heating system to a higher temperature or for longer periods of time burns up water vapor in the air. Paradoxically, that can make people feel colder. Instead, they may prefer to turn down the heat and use other ways to keep warm. Radiant heat does not create the same problems, so homeowners could consider installing radiant heating methods as a replacement. Otherwise, turning down the thermostat and wearing warmer clothes may be an adequate solution.

Keep Your Home Healthy and Comfortable

Homeowners wanting to keep a comfortable home may need to start with humidity management. People are more likely to feel too hot in the summer and too cold in the winter when the home's humidity is not in an ideal range. Homeowners can avoid many problems by paying attention to the relative humidity of the home and taking action to correct it when it gets too high or low. By adding or removing humidity based on the conditions of the home, the inhabitants will usually notice that they feel better and healthier.

Additional Reading

• https://topwindowfans.com/how-to-manage-humidity-in-your-home/
• https://www.epa.gov/mold/what-are-main-ways-control-moisture-your-home
• https://www.lowes.com/n/how-to/controlling-moisture-and-humidity-in-the-home
• https://www.apartmenttherapy.com/hot-tip-use-a-humidifier-105471
• https://homeclimates.com/blog/tips-controlling-homes-humidity
• https://paylesspower.com/blog/how-to-lower-humidity-in-house/
• https://www.marthastewart.com/1119460/how-care-humid-home-and-find-relief
• https://blog.getawair.com/6-health-symptoms-associated-with-humidity
• https://www.sansone-ac.com/homes-not-hot-just-humid/
• https://www.airthings.com/resources/home-humidity-damage
• https://www.bobvila.com/articles/why-is-my-house-so-humid/
• https://getcold.net/article/the-dangers-of-high-indoor-humidity
• https://www.huskyair.com/blog/reducing-indoor-humidity/
• https://www.coolray.com/help-guides/indoor_comfort_issues_to_much_or_too_little_humidity
• https://www.huskyair.com/blog/how-low-humidity-is-bad-for-your-household/
• https://www.sensorpush.com/articles/the-effects-of-low-humidity-on-your-health-and-comfort
• https://www.bobvila.com/articles/increase-humidity/
• https://www.servicechampions.net/blog/need-humidifier-effects-dry-air-low-humidity/
• https://www.mayoclinic.org/diseases-conditions/common-cold/in-depth/humidifiers/art-20048021
• https://www.drhvac.ca/blog/whole-home-dehumidifier-vs-portable/
• https://www.energystar.gov/products/appliances/dehumidifiers/dehumidifier_basics
• https://theozonehole.com/what-causes-low-humidity-in-a-house.htm
• https://www.airbetter.org/optimum-humidity-levels-home/