What Humidity Should a Basement Be? A Guide for the Perplexed

If you’re like many people, you may not think about the humidity level in your basement until it’s too late and moisture problems have already developed. What humidity should a basement be?

The ideal humidity level for a basement should be between 30% and 50%. You can measure the humidity level with a hygrometer, and there are several ways to adjust the humidity level to meet this range. Ventilate humid spaces, and use a dehumidifier or an AC to help remove excess moisture from the air.

What humidity should a basement be?

As a homeowner, you know that maintaining your home can be a challenging task. There are always repairs to be made and new problems to solve. And when it comes to humidity, many homeowners don’t know where to start.

This article will help you understand what humidity is, how it affects your home, and what you can do to maintain the correct level in your basement.

If you have a finished basement and spend a good amount of time in this space, controlling the moisture levels matter even more.

Failure to remove contaminated materials and to reduce moisture and humidity can present serious long-term health risks. 


What Humidity Should a Basement Be?

Basement humidity is often overlooked because most people don’t think of their basements as living spaces. Now that we know a basement’s humidity should be between 30% and 50%, it’s now time to dive a bit deeper.

Basements are prone to moisture problems because they are typically the lowest point in a home and they often have poor ventilation. These below-grade spaces need extra attention to help maintain their recommended humidity levels.

This can cause the humidity level to rise, which can lead to mold growth, damage to your home’s structure, and other problems.

Humidity that is too high can also lead to mold and mildew growth in a home due to the excess moisture in the environment that mold needs to thrive.

According to the CDC, mold exposure can cause symptoms including runny nose, wheezing, red or itchy eyes, or itchy skin. Those with serious respiratory ailments are likely to experience worse symptoms such as wheezing, shortness of breath, or even coughing up bloody phlegm.

In order to maintain the correct humidity level in your basement, it’s important to understand what that level is and how to measure it.

The benefits of maintaining the correct humidity level in your basement include preventing moisture damage, protecting your belongings from mold and mildew, and keeping your family safe from potential health hazards.

Below is a summary of what you should do to keep and maintain your basement humidity level within the desired range, as well as what we will cover in this helpful guide:

  • Measure the humidity level in your basement regularly and track it over time. This will help you determine if it’s fluctuating outside of the desired range and allow you to make necessary adjustments.
  • If the humidity level is too high, increase air circulation by opening windows and doors, using fans, or installing an exhaust fan.
  • If the humidity level is too low, consider using a humidifier to add moisture to the air. Especially if you have a finished basement and spend time in there.
  • Inspect your home for any leaks that could contribute to moisture problems and fix them as soon as possible.
  • Remove any clutter or items that could block airflow in the basement.
  • Check caulking around windows and doors and seal any cracks or gaps found.
  • Avoid storing boxes or items against basement walls in the basement as this can prevent proper ventilation.
  • Regularly clean surfaces that may be prone to mold growth, such as windowsills and shower stalls.
  • Keep gutters clean and in good repair to prevent water from seeping into the basement.

Water leaks, high humidity, and failure to properly ventilate by using exhaust fans in kitchens and bathrooms are leading causes of mold and mildew in a home. A humid basement will only add to your troubles.

Signs of High Basement Humidity

If you suspect that your basement is too humid, there are a few telltale signs to look for. First, check for condensation on walls or surfaces. Window condensation is also another giveaway of high humidity. This is a sure sign that the air in your basement is too moist. Second, take a look at any stored items.

If they are covered in mold or mildew, this is another sign of high humidity. Finally, if you notice any musty odors coming from your basement, this is also an indication of excessive moisture in the air.

If you see any of these indicators, it’s important to take steps to reduce the humidity in your basement to prevent further damage.

What Causes High Humidity in Basements?

There may be several causes for high humidity in a basement. Poor ventilation in the basement can cause high humidity levels in the space, leading to mold and mildew growth and damage to building materials.

Leaky plumbing fixtures or pipes may also contribute to high humidity in the basement, as water that is leaking out of the system will evaporate into the air, creating excess moisture that encourages mold growth.

Clogged or missing condensation lines can also lead to high humidity in basements, as this can result in water being trapped inside the walls and floors of a basement without an opportunity to escape through proper drainage systems.

Flooding or excessive amounts of rainwater entering a basement can contribute to high humidity levels, as this additional moisture can saturate the surrounding area and lead to increased dampness and musty smells within the space.

Poorly insulated walls or ceilings in the basement can allow excess moisture from outside conditions like rain or snowmelt to penetrate into the space, increasing humidity levels over time and potentially causing damage to structural components like wood framing or drywall.

Basement Humidity in the Summer

During the summer months, the humidity in your basement can rise to unhealthy levels. This is because hot air holds more moisture than cold air, and as the temperature outside rises, the air in your basement will become more humid.

To help prevent mold and mildew growth, it is important to keep the humidity in your basement between 30 and 50%.

You can do this by running a dehumidifier or by opening a window to allow ventilation.

By keeping the humidity in your basement at a safe level, you can help to prevent mold and mildew growth and ensure that your home is safe and comfortable.

Ideal Basement Humidity in the Winter

When most people think of ideal basement humidity, they think of cool, dry space. However, during the winter months, you may need to raise the humidity in your basement to prevent damage to your belongings and to your health.

If the air in your basement is too dry, it can cause wood furniture to crack and electronics to malfunction.

In addition, low humidity levels can lead to respiratory problems, such as sinus infections and bronchitis. The best way to maintain the ideal moisture content in your basement is to use a humidifier.

This will help to add moisture to the air, preventing the problems that can occur when the air is too dry.

Just be sure to monitor the humidifier so that you do not overdo it and create a damp environment, which can lead to mold growth.

How to Remove Humidity From Your Basement

To eliminate dampness from your basement, consider doing the following:

Invest in a Dehumidifier

Install a dehumidifier in your basement to remove excess moisture from the air. This can be done manually or automatically, depending on the type and model of dehumidifier you choose.

Ventilation is Key

Open windows and doors to allow fresh air into your basement, which will help dry out any excess moisture that may be present.

Add a ventilation system to your basement if it does not already have one, which will allow for increased airflow throughout this space and help reduce humidity levels over time.

Use Fans

Use fans to circulate dry, cool air around your basement in order to help remove humidity and prevent mold growth and mildew accumulation.

Repair Leaks

Seal any cracks or gaps in your basement’s walls or floors, as these openings can allow humid air to seep into the space and cause it to become damp or dampen other areas of your home.

Turn on Exhaust Fans

Run exhaust fans in other parts of your home that are adjacent to the basement, such as a bathroom or kitchen area, which will draw humid air down into the basement and away from other rooms in the house.

Use a Hygrometer to Measure Humidity

A hygrometer is a device used for measuring the humidity levels in a home. The most common type of hygrometer is the thermistor, which uses electrical resistance to measure the amount of water vapor in the air.

Thermistors are generally more accurate than other types of hygrometers, but they can be more expensive as well.

Hygrometers are important because they can help to regulate the indoor air quality in a home. If the humidity levels are too high, it can lead to mold growth and other problems.

On the other hand, if the humidity levels are too low, it can cause dry skin or furniture to become damaged and cracked.

By using a hygrometer, homeowners can ensure that their indoor air quality is maintained at optimal levels.

Leonardo da Vinci was noted to have built the first known instrument to measure the humidity of air or gas — called a “hygrometer” — around the 1400s.


Is 60% Humidity too High for a Basement?

When it comes to basements, the ideal humidity level is between 30 and 50 percent. Anything above 60 percent is too high and can lead to a number of problems, such as mold and mildew growth, musty odors, and warped wood.

High humidity levels can make it difficult to keep the basement comfortable, as the air will feel damp and clammy.

To lower the humidity level in your basement, you can use a dehumidifier or take steps to improve ventilation.

If you have a central air conditioning system, you can also use the AC to help regulate the humidity levels in your home.

Will Mold Grow at 55% Humidity?

While most molds prefer warmer temperatures, there are some that can grow at lower temperatures. And while 55% humidity is not ideal for mold growth, it is certainly possible for mold to thrive in this environment.

Of course, the type of mold will play a role in its ability to grow at lower humidity levels. For example, black mold is more likely to grow at lower humidity levels than other types of mold.

As a result, it is important to be on the lookout for signs of mold growth even if the humidity level is not ideal.

If you see any signs of mold, it is important to take action quickly to prevent the problem from getting worse.

How Long Should You Run a Dehumidifier in the Basement?

How long you should run a dehumidifier in the basement depends on a number of factors, including the size of the basement, the level of humidity, and the weather conditions. In general, you should run the dehumidifier for at least 12 hours per day during periods of high humidity.

You may need to run it for longer periods of time if the weather is particularly hot or humid, or if the basement is larger.

If you have a smaller basement or if you live in an area with moderate humidity, you may be able to get by with running the dehumidifier for shorter periods of time.

Ultimately, it’s important to monitor the moisture levels in your basement and adjust the dehumidifier accordingly to prevent mold growth.

Do I Need to Run Dehumidifier in Basement in Winter?

Many people wonder if they need to run a dehumidifier in their basement during the winter months. The answer to this question depends on a few factors, including the level of humidity in your basement and the amount of insulation in your home.

If your basement is uninsulated or poorly insulated, running a dehumidifier can help to prevent moisture from condensing on surfaces and causing mold or mildew growth.

Additionally, if your basement is prone to high levels of humidity, a dehumidifier can help to keep the air comfortable and reduce musty odors.

However, if your basement is well-insulated and does not experience excess humidity, you may not need to run a dehumidifier during the winter months.

How Much Humidity Is too Much in a Basement?

The amount of humidity in a basement should be no more than 50%. Any higher than that and becomes a breeding ground for mold, mildew, and bacteria. Not only is this a health hazard for you and your family, but it can also lead to structural damage to your home.

Basements are typically more humid than other parts of the house because they are below-grade and have limited ventilation.

To combat this, you can install a dehumidifier or take other steps to improve air circulation.

You should also make sure to keep the area clean and free of clutter, which can trap moisture.

What Humidity Should I Set My Dehumidifier to in the Basement?

Most people set their dehumidifiers to between 35% and 50% humidity. This range is generally considered safe for most people and helps to prevent the growth of mold and mildew.

However, the ideal humidity level for your basement may be different depending on the level of insulation, the amount of ventilation, and the temperature.

If your basement is poorly insulated or poorly ventilated, you may want to set your dehumidifier to a lower humidity level to prevent condensation from building up on walls and floors.

If your basement is very cold, you may also want to set your dehumidifier to a lower humidity level to prevent the formation of ice crystals on surfaces.

Ultimately, the best way to determine the ideal humidity level for your basement is to experiment until you find a setting that is comfortable for you and that prevents condensation and mold growth.

Can a Dehumidifier Spread Mold Spores?

Dehumidifiers work by removing water from the air. This can lower the humidity level in a room and make it less hospitable for mold. But dehumidifiers don’t actually kill mold spores.

So, if your unit doesn’t have a filter, the mold spores could be recirculated into the air, potentially causing more problems.

If you’re going to use a dehumidifier to help control mold, be sure to choose one that has a filter. That way, you can trap the mold spores before they’re emitted back into the air.

You should also keep an eye on the humidity levels in your home and empty the dehumidifier’s reservoir regularly.

Is High Humidity Bad for Your Health?

High humidity can have a number of negative effects on your health. It can cause respiratory problems, as the moist air can make it difficult to breathe. In addition, high humidity can lead to dehydration and overheating, as your body has to work harder to regulate its temperature.

Additionally, high humidity can create an ideal environment for mold and dust mites, which can cause allergies or asthma. High humidity can also make your skin more susceptible to rashes and infections.

If you live in a climate with high humidity, it is important to take steps to stay cool and dry. Air conditioning and dehumidifiers can help to create a comfortable environment, and keeping your skin clean and dry can help to prevent irritation.

By taking these precautions, you can minimize the health risks associated with high humidity.


Maintaining an acceptable level of moisture in your basement is important for preventing moisture problems and damage to your home.

In order to do this, it’s helpful to understand what poor humidity is, how to measure it, and what to do if it’s too high or too low.

There are many tips available for keeping the humidity within the desired range, so follow these suggestions to protect your home and belongings.


Trina Greenfield, Author
SmackDown Media LLC

About the Author:
Trina Greenfield, the owner of SmackDown Media LLC, is passionate about providing information to those interested in the air quality in and around their homes. Trina writes content about things she’s passionate about, such as safe, in-home air, educational platforms for children and adults, as well as all things family-related.