Skip to Main Content

Relative Humidity

Not controlling the indoor levels of humidity can affect the health of your family and your home. Here is everything you need to know about relative humidity.

Schedule Free Inspection

Even though you learned about humidity in school, the only way it impacted your life was when it messed up your hair when you went out. However, fast forward a couple of decades, and suddenly humidity is playing an important role in your life; at least keeping it out of your house is. Humidity may seem completely harmless until you realize it can compromise the structural stability of your home and even lead to health issues among members of your family. 

High humidity can turn your home into a much less comfortable living space. It can boost mold growth which can cause respiratory problems, as well as attract various pests that can wreak havoc all over your home. Also, humidity can trap harmful allergens that cause nose, eye, and throat irritation. When you add structural problems to the equation, it is easy to see why keeping humidity levels under control should be on your to-do list. 

crawl space humidity measurement

What Is Relative Humidity? 

Relative humidity will tell you how much moisture is currently in the air compared to what the air can hold at that temperature. Some of the factors that can affect relative humidity are air saturation, temperature, and the dew point. Due to these changing factors, relative humidity is always changing as well.  

Relative humidity is expressed in percentages. The higher the percent, the more humid your air is. 

What Is the Ideal Level of Indoor Humidity? 

According to The Environmental Protection Agency (EPA), you shouldn’t allow the humidity level to drop below 30% in the winter because these decreased levels can irritate your respiratory system and impact your home’s structure as well. On the other hand, it should not rise above 50% in the summer. Most homeowners find 30% to 50% most comfortable, and this is the level that prevents microorganism growth. 

How to Measure It 

Measuring the level of humidity in your home is rather easy. All you need is to get a psychrometer, a device that comes with two thermometers. This device measures the humidity of the air by comparing the difference in temperature between a dry thermometer bulb and a wet one. It is important to keep the humidity level in your home under control as when relative humidity becomes too high or too low it can cause a wide range of problems that can impact your health and the health of your loved ones, as well as your home’s comfort. 

Effects of High Humidity Levels 

If the humidity levels in your home are too high, here are some of the problems that may pop up: 

Lowers indoor air quality: Various fungi, bacteria, and viruses thrive in moist places and can easily spread throughout your home. They can contaminate the air you breathe and cause a range of health issues. 

Aggravates health issues: If any of your family members have respiratory problems, such as asthma, or have allergies, their condition will worsen if the humidity levels rise. 

Damages your structure: Fungi that attack the wood and cause it to rot are attracted to humid places. Decaying wood can compromise the stability of your home and lead to a musty smell and termite infestations. High humidity can even damage your floors, art pieces, furniture, and even electronic devices. 

Increases your energy bills: Since your home will become damp due to high levels of humidity, you will need to run your air conditioner more often than you would. This will impact your energy bills and cause you to spend more money. 

Effects of Low Humidity Levels on Your Home 

If, on the other hand, the levels of humidity in your home drop below the desired level, this can also cause a myriad of problems. For example, air that is too dry can irritate the mucous membrane and make asthma and allergy symptoms flare up. Also, flu viruses spread more quickly in these conditions, so there is a higher risk of sinus infections. At the same time, you may struggle with chapped lips and dry skin. When it comes to ways it can damage your home, low humidity levels can cause cracks in walls and ceiling, separate your wood floors, and shrink your door and window frames. 

How to Control Relative Humidity in Your Home 

As a responsible homeowner, you should make an effort to manage indoor humidity. Here are some of the ways you can keep humidity levels in your home under control: 

Crawl Space Encapsulation 

If you have a crawl space that is not protected in any way, moisture can easily enter your home through it, increasing the humidity levels. To prevent this problem, contact your local contractors and encapsulate your crawl space. With a protective vapor barrier that covers the walls and dirt floor, the outside air won’t be able to seep through it. 

Seal Crawl Space Vents 

If you have a vented crawl space, you might want to consider sealing the vents. Warmer air holds more water. So, once outdoor air enters your crawl space, it will create an excessive amount of humidity and snowball into any number of issues.  

If you live in a coastal region, the air will absorb water from the ocean, which will make it even more humid. When your vents are open, they let the humid air into your crawl space. Through condensation, warm air can introduce dampness into the crawl space and causes all sorts of problems. To prevent this, seal your crawl space vents with durable vent covers and stop the outdoor air from entering your dry crawl space. 

Install a Dehumidifier 

A dehumidifier is a useful appliance that can control the levels of humidity in your basement or crawl space. It removes excess moisture from the air and makes it less attractive to mold, fungi, pests, and other uninvited guests. 

Whether you wish to install a dehumidifier or to encapsulate your crawl space, call AFS Foundation & Waterproofing Specialists and schedule a free inspection. We offer our services to homeowners in Alabama, Mississippi, Tennessee, and Georgia, so contact us today and after a thorough assessment, our experts will recommend the best waterproofing solutions for your home.

Publish Date:

Last Modified Date:

AFS Coverage Map


Birmingham, AL

130 Interstate Commerce Crt. Bldg. 100 & 200
Alabaster, AL 35007

Chattanooga, TN

214 Industrial Park Dr.
Soddy-Daisy, TN 37379

Columbus, GA

2701 Opelika Road
Phenix City, AL 36870

Huntsville, AL

2415 Jordan Road
Huntsville, AL 35811

Knoxville, TN

3028 E Governor John Sevier Highway
Knoxville, TN 37914

Mobile, AL / Biloxi, MS

3131 Hamilton Blvd.
Theodore, AL 36582

Montgomery, AL

445 Dexter Avenue, Suite 4050
Montgomery, AL 36104

Nashville, TN

1519 Heil Quaker Blvd.
LaVergne, TN 37086