Key takeaways: 

• A high humidity level in your home is above 60%. 
• For the best comfort, keep the humidity level between 40%-50%. 
• A portable dehumidifier is a temporary solution for one area, while a whole-house dehumidifier decreases humidity throughout the home. 

By Anne Fonda

High humidity can negatively affect your indoor air quality (IAQ) as well as your home and belongings. But there is a lot that you can do to reduce humidity levels and protect your health and home. 

Let’s start with some basics. 

The Environmental Protection Agency (EPA) considers a relative humidity (RH) of 60% or higher to be high humidity. For optimal comfort and health, they recommend an indoor humidity level between 30% and 50%.  

Both sudden and longstanding problems can cause high humidity in your home.  

• High outdoor humidity in the summer or year-round 
• Flooding 
• Slow water intrusion in your basement or crawlspace 
• A plumbing leak 
• An air conditioning system with inadequate dehumidification capabilities 
• Poor ventilation 
• A combination of factors 

High humidity can lead to some serious problems. 

There are a lot. Some you can feel, some you can smell, and some you can see. Common signs of high humidity/excess moisture include: 

• Cold, clammy feeling when the AC is running 
• Sticky feeling 
• Difficulty sleeping 
• Doors and windows swell and stick 
• Musty smell 
• Mold and mildew growth 
• Increase in dust mites and pests 
• Condensation on walls, windows, or pipes 
• Peeling or bubbling paint and peeling wallpaper 
• Wood rot or crumbling concrete in the basement or foundation 

In addition, according to the Asthma and Allergy Foundation of America (AAFA), family members with allergies or asthma may have increased symptoms such as sneezing, itchy eyes, or difficulty breathing.  

The fix for excess humidity depends on the root cause. 

You may have high humidity only in certain rooms, such as the bathroom or basement. 

In a bathroom, the likely culprit is inadequate ventilation. Consider installing a bathroom exhaust fan, opening a window during showers, and opening the door as soon as you can to let humid air escape. 

If you have water intrusion in your basement or crawlspace, you will need to solve that problem first, potentially with basement waterproofing or crawlspace encapsulation. Fixing the root cause may return your home humidity levels to normal. 

If you had flooding or a plumbing leak, fixing the leak and throwing out or drying out water-damaged materials should fix any temporary high-humidity problem. Keep in mind that wet drywall and insulation should be disposed of. Replacing the carpeting and padding is the safest way to avoid mold growth. 

Carpet and carpet padding may be dried, but it takes some work. A portable dehumidifier can help remove moisture from the air, while a wet-dry vac can help extract water from carpeting. Depending on how long the leak was active or how long you had standing water, you may have rotting wood in the subfloor.  

If you have higher humidity throughout your home, you need whole-home solutions. If you have an older home with leaky doors and windows that let warm, humid air in, consider some weatherization projects such as sealing gaps and adding insulation to keep conditioned air in and help keep humid air out. 

You could also consider upgrading your HVAC system to a variable-speed system, which does a better job at dehumidification than a single-stage or two-stage air conditioner. 

"Another, more affordable alternative is to add a whole-house dehumidifier. A whole-house dehumidifier can be installed as a standalone unit or connected to your existing ductwork to utilize your HVAC system fan. It’s an excellent solution for homeowners with a single-stage system in a high-humidity area. It’s a whole-house solution and a better fit than a portable dehumidifier."

- Sean Goddard, Product Manager, Coils & Indoor Air Quality 

Common installation areas include: 

• Basement 
• Crawlspace 
• Attic 
• Utility room 

Trane offers an energy-efficient whole-house dehumidifier with optional ventilation suitable for homes up to 3,000 sq. ft. and capable of removing up to 120 pints (15 gallons) of water from the air daily. Your local Trane dealer can assess your home’s humidity and recommend the proper dehumidifier capacity and placement for maximum effect. The dehumidifier will need a power supply and a drain system. 

The Awair Element™ indoor air quality monitor measures the temperature, levels of pollutants, humidity, and more. When it’s connected to your HVAC system, humidity levels above the Good range (40-50%) can trigger the air conditioning or whole-house dehumidifier to come on, without you lifting a finger. 

“Homeowners often overlook how crucial indoor air quality is to their family's health and comfort. With the Awair Element integrated into their Trane HVAC system and Trane smart thermostat, they gain real-time insights into temperature, humidity, and pollutants.”

-David Lothe, Communications and Accessories Product Manager 

 “This smart device empowers homeowners to maintain a healthier living environment, providing peace of mind and optimal comfort. They can breathe easier knowing their indoor air quality is continuously monitored and managed," Lothe continued. 

Concerned about high humidity? Worried about indoor air pollutants? Visit our Indoor Air Quality Guide to learn more, and then contact your local Trane dealer for an air quality assessment and effective solutions to control humidity. 

Anne Fonda, Content Writer

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A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.

When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by Sean Goddard, Product Manager, Coils & Indoor Air Quality