How to Control Humidity in Your Home

Updated on January 25, 2022 by Joseph D. Nielson

Table of Contents

Woman standing behind glass with humidity holding her finger to the glass

We hear the word all the time and most people have a pretty good idea of what it is. But humidity levels in your home impact your family’s health, the structure of your home and your valuable possessions. So understanding what humidity is and how it works is crucial to protecting your home and loved ones.  Keep reading to learn more about humidity’s impact in the home, what the risks of high and low humidity are and how to protect against them.

What is Humidity? 

In a nutshell, humidity is the amount of water vapor in the air. When water is in a gaseous form, it’s called vapor. There is always some amount of water vapor in the air. Water goes through a constant cycle of evaporating into a gaseous state and condensing to become liquid again. During evaporation, water is warmed up enough to escape its liquid form and turns into tiny droplets of water small enough to be trapped in the air like a gas – this is water vapor. The more water vapor in the air, the more humid it is. That’s why you hear people talk about “moisture” in the air. They are talking about the amount of water vapor.

A Quick Lesson on Relative Humidity

When we discuss humidity in the home and how it affects your family and the structure of your home, we often refer to relative humidity. Relative humidity is also something you always hear about in weather reports.

Without getting into too much detail, relative humidity is the amount of moisture in the air at a specific temperature compared to how much water vapor the air can “hold” at that temperature. Technically speaking, air doesn’t hold water vapor because it moves too quickly. 

When the air outside reaches 100% relative humidity, it rains. When the air in your home reaches a specific water vapor capacity, or relative humidity, it will make the air feel damp and condense as moisture when it hits a cool surface.

How Does Humidity Affect the Human Body?

Heat and humidity are related. The higher the temperature of an area, the more water that evaporates. That’s why people complain about humidity in the summer and say, “It’s not the heat, it’s the humidity!” When the human body gets hot, it also releases moisture, in the form of sweat. But the air in summer is often already saturated with moisture from water vapor because of a high relative humidity which makes it feel “muggy” outside. This prevents our sweat from being evaporated into the air and makes us feel “sticky”.

On the flip side, there’s also a possibility that there’s too little humidity in the air, making us feel cooler than we should in relation to the temperature. This is low relative humidity. This can happen in the winter when the air is cool and dry from the lack of water vapor or moisture. The air helps our sweat evaporate quicker than it normally would, sending a signal to our bodies that it’s cold.

What Are the Ideal Indoor Humidity Levels?

It’s recommended that you keep your home’s relative humidity between 30 and 50% – above 30-35% in the winter and below 50% in the summer.

Too much or too little humidity on the home can affect health and cause structural damage to our homes. That’s why it’s also recommended to install an air quality monitor in your home to act as an early warning system and help you prevent the following conditions.

Woman and man wearing bathing robes standing in front of a bath tub and looking out the window while hugging.

Health Effects of Humidity in the Home

Both low and high relative humidity levels in the home have been linked to health problems such as:

Respiration Issues

When relative humidity is above 50%, it makes it harder to breathe, which can worsen existing respiratory conditions. 

The constant moisture in the air also encourages the growth of mold and dust mites, which wreak havoc on both the structure of your home and your family’s health. They are often associated with the development of asthma and allergies. People in homes with mold and damp conditions are more likely to suffer from:

  • eye, nose and throat irritation
  • coughing and mucous (phlegm) build-up
  • wheezing and shortness of breath
  • worsening of asthma symptoms
  • other allergic reactions

Too little humidity in the home, on the other hand, can cause respiratory illnesses, dry sinuses, itchy throat and eyes. It’s also the ideal condition for spreading viral infections like the flu and COVID-19. That’s why cases and transmissions increase in the winter – because of the cool, dry air. 

Skin Issues

Low humidity is also known to cause dry skin and eczema. Dry air can extract moisture from the skin drying it out and aggravating conditions like eczema. If you know someone suffering from dry skin or eczema, help relieve their pain with the best humidifier for small rooms.

The dry air in a low humidity environment can also damage the tear film in your eyes.

How Does Humidity Affect Your Home?

One of the major concerns of high relative humidity is the growth of microorganisms like mold, dust mites and mildew. Not only do they cause the health issues mentioned above, but they can cause and promote damage to your home.

As they grow and spread, they feed on materials in the home like drywall, wood, carpeting and clothing.

The moisture in the air also impacts household items and structures. An excellent example of this is in bathrooms. Bathrooms are constantly exposed to high humidity when we shower. That’s why it’s common for wallpaper and drywall tape to peel in a bathroom. The same holds true for the rest of your home. If you notice these issues in other areas of your home, it’s probably due to excess moisture in the air.

Other humidity-related damage to the home includes:

Framing, Furniture and Floors

Wood is used everywhere in the home and is affected by humidity and moisture. Too little humidity and dry air can cause the wood’s natural moisture to evaporate, causing it to warp. Excess moisture can cause wood to swell, warp and/or decay.

So, in other words, having the right level of humidity is necessary to prevent damage to floors, baseboards, joists and studs. 

Humidity and Wall Damage

Like wood, drywall and plaster are also affected by humidity and moisture. While drywall covering the inside of exterior walls is protected by vapor barrier (at least it’s supposed to be), high relative humidity and moisture changes can also cause drywall and plaster in all areas of the home to swell, contract and eventually crack.

Another concern is moisture forming around the foundation of your home’s exterior. Any cracks can cause moisture to leak into your basement, leading to structural damage and significant repairs.

Brick wall with cracks

Humidity and Electronic Devices

High humidity in a home also impacts expensive devices we rely on constantly. As the air in your home contacts the cold external surfaces of your devices, wiring and electronics, excess moisture in high humidity condenses back into tiny droplets of water. Worse, some devices and electronics have ventilation systems with openings. So high relative humidity can produce moisture on the insides of those electronics. 

Water is known to corrode wiring and short circuit electronic components like microchips, processors and hard drives. Not only do we need these devices to last as long as possible, repairing them is costly.

Damage to Windows

You’ve more than likely seen condensation on surfaces like windows and mirrors. The cool surface of a window or mirror condenses the water vapor and turns it back to the water droplets you see running down your window or mirror. 

The problem is those droplets collecting on window frames and other wood surfaces that cause the wood to warp and shift, leading to window damage.

Sources of Humidity in the Home

There are many daily activities we perform and appliances we use that add to the problem of high humidity in the home. Leaks and other damage to the exterior of your home are also sources of condensation and moisture inside the home. Here is a closer look at some of the culprits:

  • The environmental conditions in your area of the country play the biggest role in the relative humidity inside your home. Learn the humidity best practices for the climate in your area.
  • Leaks and cracks around exterior walls, windows and the foundation of the home can allow moisture to seep in.
  • Blocked gutters and downspouts cause water to build up and fall at the source of the blockage instead of flowing through the system and away from your home.
  • Showers. Most people use a warm-to-hot water temperature when they shower. This usually leads to paint, wallpaper and plaster damage. It can also lead to mold growth. Escaping steam from the bathroom after a shower also adds humidity to the home. 
  • Cooking and boiling water add excess moisture to the air.

Use the tips below to address these issues.

How to Lower Humidity Levels

Below is a good mix of major and minor upgrades as well as some things you and your family can do around the house to lower the humidity when you notice you have high relative humidity in your home.

Protect Your Home Inside and Out

Some of the repairs and improvements you can make include:

  • Fix plumbing leaks right away.
  • Repair cracks and leaks in the roof, walls, window frames and foundation.
  • Slope the grade of the landscaping around your home away from it where possible to drain rainwater and snowmelt away from the structure.
  • Clean your gutters and clear all obstructions from eavestroughs and downspouts to ensure that the system flows water correctly away from your home.
  • If you finish your basement or do any drywall work yourself, make sure to vapor-barrier and insulate exterior and foundation walls and use moisture-resistant sheetrock in kitchens and bathrooms.
  • Use moisture-resistant countertops, cabinets and construction materials when renovating kitchens, bathrooms, laundry rooms and anywhere else with a lot of moisture.
  • Make sure bathroom and kitchen fans ventilate properly and efficiently (no leaks) to the outside.
  • Replace old, drafty windows with energy-efficient upgrades, ensure window frames are not damaged and caulk the interior and exterior around them. 
  • If it isn’t already, make sure your clothes dryer vents to the outside and hang-dry clothes outdoors when possible.
  • Use the right sized AC in your home, along with your existing mechanical ventilation system. If you don’t have one and are considering installing a ventilation system, use one with a Heat Recovery Ventilator (HRV) or an Energy Recovery Ventilator (ERV).

Monitor Problem Areas

  • Use a dehumidifier in damp areas like your basement when you know that relative humidity is going to be high.
  • If you notice condensation on your windows, wipe the frames and sills with a dry, moisture-absorbing towel like a chamois.

Be Mindful During Daily Activities

  • Always use your bathroom exhaust fans while you shower and keep them running afterwards if you still notice steam on the mirror. Open the nearest window when you can.
  • Always use the fan in the range hood and open a window, if possible, when cooking and boiling water.
  • Keep heating and cooling vents clear of furniture. Also move furniture away from walls and room doors open when the windows are open to ensure airflow is distributed throughout your home. The same goes for when the heater is on.

How to Maintain Comfort Level with More People at Home

When we have guests over, most of us wait until the house is already too hot because of all the body heat to open a window or sliding door. While this can cool things down in a hurry (especially in the winter), surfaces in your home will cool faster than your guests and become prime targets for moisture condensation. 

Plan ahead for parties and get-togethers and use your home’s ventilation system or have fans plugged in and ready to go as soon as you notice the temperature rising.

How to Prevent Low Relative Humidity in Your Home

In the winter, when your monitor tells you humidity is low or when you notice dry air, one of the easiest and healthiest things to do is use a combination air purifier and humidifier to raise the humidity in your home. When heating up cold areas of your home, you can potentially save on energy bills and take control of low humidity and respiratory health by using the air purifier/humidifier in combination with one of the best space heaters for large rooms.

Other tips include:

  • Add plants around your home.
  • Opening the dishwasher as soon as it’s done to let the steam out. 
  • Air dry clothes indoors
  • Boil water without the fan on.
  • Shower with the bathroom door open.

To Sum it All Up…

Having the right humidity levels in your home year-round can help you avoid illnesses and respiratory issues and protect the structure and furnishings in your home. 

Install an air quality monitor to know where you stand and use the above tips to gain control over your home’s humidity. 

Joseph and Family
About Joseph D. Nielson

Former journalist and editor for various press groups, I now dedicate my time to reviewing products for the home and family life. When I get time to myself, I enjoy rock climbing, taking my dirt bike for a rip, and most importantly providing my family with the best home possible!