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What Causes High Humidity In A House?

What causes high humidity in a house

When the temperatures begin to climb, you may detect some changes around your home. Perhaps you catch a whiff of musty air and notice that your windows are getting foggy. Or, maybe you’re relaxing in the kitchen with a glass of lemonade and suddenly you start sweating even though you’re not exerting any physical energy beyond lifting your glass. You might even spot damp spots on your walls and what looks like mold in your shower.

If any of this sounds familiar, your home may have a problem with excessive humidity because your air conditioner is not controlling the level of moisture in your indoor air. Not only will it make you hot and uncomfortable, but also high interior humidity can cause more serious problems like mold, mildew and rust, along with posing potential health risks.

In parts of the country that have hot and humid climates, homeowners often call AC repair companies about overly humid houses every year when the weather starts to warm up. Ready to put an end to this sticky and heavy feeling in your house once and for all? We’ll tell you all that you need to know about indoor air comfort, why houses can become humid and most importantly, what you can do about it.

Let’s start at the beginning.

What Is High Humidity, Exactly?

“It’s not the heat, it’s the humidity.”

You’ve probably heard that phrase a number of times in your life, especially if you live in some of the wetter, hotter parts of the country. Maybe you’ve even used it yourself.

Have you ever asked yourself what exactly is humidity?

In basic terms, humidity is the measurement of water vapor in the air. When the air retains more water vapor, the environment will feel more humid. When the air retains less water, the environment will feel dry.

Generally, people feel most comfortable at a low to medium amount of humidity. Too-low humidity may be uncomfortable and detrimental to your home and house. Excessive humidity, on the other hand, is also not what most individuals would prefer, and can cause both health and home complications.

Ranking humidity on a scale of 1 to 100 with 100 being the highest level of humidity possible without rain, you generally want your home to be somewhere between 45 and 55 percent humidity.

Why is my house so humid

Why Is My House So Humid?

What causes excess humidity in a home? Simply put, high humidity in a home occurs when moisture comes into a home and cannot get out. The main way that your home’s humidity level is controlled is through your air conditioning system.

Apart from your AC not properly removing humidity from the air circulating inside your home, here are three of the most common ways excess moisture gets into your house and causes humidity:

  • Everyday activities. You may be surprised to learn that many of your daily activities may be introducing excess moisture into your house. Everyday actions like cooking, washing the dishes, running the washing machine, taking a shower, sweating and even breathing can cause moisture to build in your home—especially if you’ve got a big family.
  • Leaks. Moisture could also be entering your house through leaks and cracks in or around your home. To find the culprit for these types of issues, look around for leaky pipes, a cracked roof tile or a loose zinc joint or fitting.
  • Rising damp. Rising damp is a rarer, but more serious cause of high humidity in a home. Rising damp occurs when moisture from the ground rises through the pores in the bricks and masonry. Keep an eye out for symptoms of rising damp, such as mold, rotting window frames, flaky plaster or damp or wet patches on your walls. If you have reason to suspect rising damp in your home, it’s definitely time to call in the professionals.

High humidity in house health problems

High Humidity In House: Health Problems

When humidity grows beyond 60 percent, you’ll find you feel clammy and uncomfortable. But as mentioned above, feeling overheated isn’t the only problem with high humidity. There are many other health consequences of humidity—and some of them can be quite serious.

Here are some of the biggest health problems caused by high humidity in a home:


As the humidity in your surroundings rises, it becomes increasingly difficult for our bodies to keep us cool. Sweat doesn’t evaporate effectively in humid weather, so our bodies pump out even more sweat to try and compensate. Excessive sweating can lead to loss of water and essential minerals that your body needs.

Your body will start using other defense mechanisms to try and protect you against overheating, including increased respiration and altered blood flow. All of this can put you at risk of dehydration, respiratory problems, fatigue, muscle cramps, and more.

Sleep Problems

High humidity has been linked to sleep problems. When humidity is high and you feel overheated, you may find yourself tossing and turning all night long, leading to less restful sleep. Humidity can also increase congestion, disrupting your breathing and causing snoring.


Bacteria love moisture, and a damp house can lead to bacterial colonies growing on moist walls and floors. Dust mites also thrive in warm, humid environments. High humidity also welcomes in harmful molds, which can contribute to allergies, asthma attacks and many other health concerns.

It doesn’t stop there, either. Beyond health problems, an overly humid home can have a negative impact on the structure of your house as well. Too much moisture in your home can cause the wood in your home to swell, rot and deteriorate. High humidity can even encourage rust and oxidation.

How to remove humidity from a room without a dehumidifier

How To Remove Humidity From Your Home Without A Dehumidifier

Considering the comfort, health, and structural concerns caused by an overly humid home, it’s essential to tackle this problem as soon as possible.

One solution many homeowners try to remove humidity is to get a dehumidifier. These devices collect moisture from the air in your home in a bucket that you empty periodically. However, using a dehumidifier is a temporary fix and only one of the many ways you can remove moisture from the air in your home.

Luckily, there are some other ways to get rid of humidity in your house without a dehumidifier.

Run The Air Conditioner

A functioning, high-quality air conditioning system essentially acts like a dehumidifier, removing moisture from the air as it cools. If your home stays humid, you likely have a problem with your system. Be sure to perform routine maintenance and regularly replace the filters on your air conditioner as well as your furnace, as clogged filters can stifle airflow.


Activities like boiling food, taking hot showers and even breathing produce moisture in your home—moisture that will get trapped if it has no way to escape. That’s why proper ventilation is essential to preventing high humidity. You can help to ventilate your home by doing several simple things.

Cracking open windows, particularly in high-moisture areas like the bathroom, is very helpful. Ventilation fans are one of the most effective ways to combat humidity, and you should consider having them professionally installed if you do not have these in your kitchen, bathroom and laundry rooms.

Cool Down Your Showers

To reduce humidity, taking shorter, colder showers can help. You may also want to consider using a low-flow showerhead or showering with a partially opened tap. Thankfully, when temperatures are warmer, you’ll probably want cooler water temperature in your shower, anyways!

Be Mindful Of Your Cooking Habits

When you cook, make sure to switch on the exhaust fans over your stove and cover your pots. You may also want to try using slow cookers, which produce less moisture than oven and stovetop cooking.

Move Your Houseplants

Did you know that water can evaporate from the exposed soil of your houseplants? To reduce humidity, you may want to move them outside, even just temporarily. Also, avoid overwatering your indoor plants, as this can contribute to your problem.

Dry Your Clothes Outside

Your dryer could be a major culprit behind your humid home. You can prevent excess humidity by drying your clothes outside on a clothesline. If you do use a dryer, make sure it’s vented to the outside.

High humidity in house with air conditioning

High Humidity In House With Air Conditioning–What Gives?

We mentioned above that running your air conditioner is usually the primary way to combat high humidity in your home. However, if you feel humid, hot, and clammy even with your AC on full blast, there could be a problem with your unit.

Common causes of high humidity in a house with air conditioning include:

  • Oversized unit. Contrary to what you might think, an air conditioning system is less effective at controlling temperature and humidity if it is too large. This is largely due to the power of the compressor, which allows it to run for short periods of time—too short to remove all the humidity from the air.
  • Frozen coils. Your AC coils won’t be able to perform their job effectively if they’re covered in frost. As a result, your air conditioner won’t cool or dehumidify the air as well as it should.
  • Dirt and dust. Even if you regularly replace the air filter of your AC unit, dust, dirt and other debris will still collect in the system over time. If you don’t have the expertise nor time to perform the tasks on the manufacturer-recommended air conditioner maintenance checklist, enlist the help of a licensed professional.

ABC Can Make Your Home More Comfortable

Excessive humidity in your home is a serious concern that should be addressed as soon as possible. If you continue to experience problems with interior humidity, it’s time to seek professional expertise. The longer you wait, the worse this problem can become. Since most of us homeowners are not professionally trained in how HVAC systems work, the best way to handle these types of issues is to get in touch with ABC Home & Commercial Services. Our experienced technicians have been working with AC systems for more than 60 years. We can help you locate the cause of your overly humid home and put an end to the problem, once and for all. Your home should be a refuge from the summer heat, so give us a call and let the pros at ABC turn your home into the cool oasis you need to survive summers in the southern states.

Tom Riggs

Tom Riggs is the Division Manager for Mechanical Services, overseeing sales and operations for HVAC, Plumbing, Electrical, Appliance Repair and Water Quality for all ABC Austin branches. He joined ABC in 2014. Before ABC, he was an HVAC Service Technician, HVAC Comfort Advisor/Sales and Operations Manager. Tom attended Universal Technical Institute. He's an avid outdoorsman and enjoys country living with his wife and two sons.

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