What humidity does mold grow?

3 Key Takeaways:

🚀 Mold thrives in areas with high humidity levels, specifically in areas with a relative humidity of 55% or higher.

🚀 Maintaining ideal indoor relative humidity levels is important to prevent mold growth.

🚀 Dehumidifiers can help manage high humidity levels by extracting moisture from the environment, keeping it dry and free from the growth of mold and mildew.

Relative humidity and mold growth are a balance that many homeowners struggle with. Maintaining the ideal relative humidity reaps several benefits, likewise, problems arise when the relative humidity level is not maintained.

Many still wonder at what humidity does mold grow, the causes and consequences of not maintaining the relative humidity in a space. In this article, we will discuss each of these factors in detail. Let’s get started!

How is Mold Formed?

how mold is formed

Mold growth is harmful to both us, humans, and to the property around us. The problems that arise from mold growth are plentiful. It must be a priority to focus on keeping our home and surrounding safe from mold growth and preventing mold growth at all costs. Some temperature and humidity levels might make it difficult to prevent mold growth, however, they can also be handled by maintaining the indoor humidity levels and the relative humidity levels at a constant.

Let us take a look at the reasons or conditions in which mold thrives:

Excess Moisture

A good moisture source and high humidity levels are all that mold requires. Mold spores and mold grows in dark and moist areas that have little to no moisture control. If your home or environment has constant moisture problems, you must concentrate on methods to remove moisture at once.

As long as moisture problems persist, you will also have a mold problem. Mold growing on damp wood, wet building materials, wooden floors and furniture, bathrooms, laundry room, kitchen, leaky roofs, etc., happens for one reason. All these are moist areas, dark, and the best places for indoor mold.

To kill mold growth completely is difficult but is possible. An indoor mold problem can be tackled with proper mold remediation. However, the first step is to find a permanent solution to the moisture problem. No matter which space, when mold spores come in contact with enough moisture to sustain them, that is all mold requires to have your home filled with hidden mold. All types of molds can thrive in excess moisture, black mold, yellow mold, etc. To prevent mold growth from all areas of your home, execute moisture control.

Excess humidity levels

Maintaining the ideal indoor relative humidity level is important for various reasons, one of the most important ones being to prevent mold growth. Preventing mold growth by having the relative humidity under control is possible.

Just like moisture, mold grows in high humidity areas. Humidity mold will thrive in any area that has a relative humidity RH of 55% or higher. The high indoor humidity level is another supportive factor of mold growth. When it comes to temperature and humidity, it has been found that mold can flourish effortlessly and part of its negative effects on its surroundings in an area that has a high humidity level for an adequate amount of time. If low humidity conditions do not visit the place and the relative humidity RH stays high, mold is going to thrive.

A smart way to kill mold is to have air flowing freely inside the room or home. Prevent condensation or identify condensation by noticing the windows and act upon maintaining the relative humidity level without delay. The simplest and most efficient way to maintain the temperature and humidity level in an area and prevent condensation is to invest in relative humidity monitors and dehumidifiers.

While relative humidity monitors will help to keep track of the relative humidity RH of the space, dehumidifiers will act upon moisture problems, removing moisture from the air, and maintaining the ideal absolute humidity level and ideal indoor relative humidity. Thereby, preventing humidity mold in the area with ease.

High temperatures

Mold growth takes place in an environment that has constant temperatures. If your home or room is maintained with consistent temperatures, you will find hidden mold growing. Rooms or homes that do not have a change in temperatures, whether by using air conditioners or heaters, it is going to be easier to find mold growth in them.

High-temperature areas are the best suitable for mold growth. Spaces like air ducts, appliances, leaky roofs or hot roof areas, cracking in ceiling tiles, clothes dryers, crawl space, indoor environment or indoor space exposed to heat apart from direct sunlight, duct work, etc. Although these places seem like the perfect environment to be called warm areas, they might still turn into the right temperature with the perfect environment for hidden mold.

Warm areas or high-temperature places that have a consistent temperature range of 70-degree Fahrenheit or more are the ideal range for mold to grow. Regulating the temperature of your indoor environment; in the basement, crawl space, roof, and all rooms by using a cooling system like air conditioning will help to solve the issue and effects of high temperature and mold growth.

Oxygen level

The problems that arise when we want to kill mold growing causing structural damage and health problems arise with cutting off the oxygen supply. Like all living organisms, molds require oxygen. The issue is molds can grow with minimal levels of oxygen and therefore it is a challenge to kill mold and mold spores without expert help.

Use a polymer sealant to reduce oxygenation on areas that you suspect will help mold grow.


Just like mold remediation takes time, so does growing mold. Different types of molds grow at different paces, however for mold spores to begin proliferating it takes time. For mold to grow successfully the temperature and humidity must remain stable and unchanged.

Available food source

For mold to grow and spread its mold spores, there must be a viable food source available at all times. Damp roof and ceiling tiles, wet building materials, wood flooring with standing water, wall cavities, cabinets with enough moisture, appliances like clothes dryers, exhaust fans, air conditioners, air ducts, or devices with duct work, basement and crawl space, etc.

A home affected with mold and moisture problems is at the risk of structural damage and losing its structural integrity. It is important to remove mold with all its effects to bid adieu to the issue completely.

How do you know if mold is making you sick?

feeling sick with mold

The mold problem comes with adverse side effects for both you and your home.

Hidden mold can lead to several health problems that can be identified with symptoms. Frequent asthma attacks, allergies, difficulty breathing, headaches, wheezing, skin irritation, etc., are a few of the many health problems that come when mold grows. If you or your family members have pre-existing health diseases, it is important to discourage pests of all kinds and kill mold growth, black mold, and mold spores. Take measures to permanently remove the mold problem.

The structural integrity of a home is compromised when it is filled with mold and mold spores. Structural damage can take place when there are enough moisture problems and condensation in the house, standing water, excess cold surfaces, and water vapor, mold growing in wall cavities, poor air quality in the indoor space, moisture in building materials, lack of direct sunlight, standing water in crawl space, unable to identify the moisture source, high humidity in the basement area, excess moisture in the air, etc.

Each of these problems will lead to poor structural integrity. Act swiftly to remove moisture using dehumidifiers and get rid of the moisture problem. This will diminish the mold, mold spores, dust mites, and also discourage pests of all kinds.

Removing the moisture problems will be a good start to leaving behind difficulty breathing, allergies, and other symptoms from dust mites, mold, and mold spores.

How Humidity Impacts on Mold Formation?

  • When the relative humidity level is above 55% it leads to mold growth. Dehumidifiers can be used to monitor and maintain the relative humidity levels at the desired point.
  • Higher humidity levels lead to water vapor condensation. Water vapor barriers can be used to resolve this.
  • High relative humidity levels alter the comfortable temperature range. Fungi can thrive in humid temperatures.

Learn How to Prevent Mold From Experts

The key to removing mold from the home is to prevent mold growth. Take steps to stop the mold problem from growing or escalating. Here are a few of the measures that experts advice to prevent mold growth and to get rid of all types of molds.

Keep a track of the humidity that exists in your home. Add humidity control to your priorities and maintain indoor relative humidity seamlessly. Invest in humidity monitors that make indoor humidity maintenance easier. Dehumidifier, thermometer, hygrometer, are devices that will help to identify high humidity or low humidity and maintain the indoor environment accordingly. Keeping your indoor space free from low humidity and high humidity issues, dust mites, molds, etc., starts with humidity control.

Do not procrastinate fixing leaks. Any leak in air ducts, wet building materials, stagnant water, air conditioner leaks, cracks in windows and doors, etc., must be fixed at the earliest. We often fail to look at small leaks through the walls that can happen with air conditioners. If you suspect an issue with the air conditioning in your home and the air conditioner has to be looked at, do it without delay.

Ventilate the area adequately. When there is air flowing freely, it not just acts as a natural cooling system but also ensures there is enough moisture and is not in excess, and removes chances of condensation. Free air movement and not relying on air conditioning, minimizes the growth of molds.

A well-ventilated place is not the ideal food source. Lack of moist or warm areas will discourage pests and other moisture problems.

Can you clean up mold yourself?

Trying to remove molds by yourself can go either way. You might either get it done right or make the problems worse. Getting professional help with mold remediation is advised since they will do thorough work on molds growing in spots you may miss out. The ducts and pipelines within air conditioners and clothes dryers, crawl space, any cold surface that seems suspicious, etc.

Some types of molds are dangerous and must be dealt with caution. Removing the moisture problem at the root can be done by professionals alone. They might suggest you invest in a hygrometer and dehumidifier to ensure the problems from molds don’t recur.

FAQ Section

1. At What Temperature Does Mold Die?

Most types of molds are sensitive to heat and will die at high heat temperatures. A temperature of 140-160°F (60-71°C) is found effective to destroy mold. There are high-temperature treatments that can kill molds at these temperatures. Nevertheless, it has also been found that some varieties of mold generate spores that are resistant to high-temperature treatments too. This can be the reason why you find mold growing on pickled vegetable products despite the temperatures they are at.

2. Is there a mold detector?

Yes, the basement spaces have much more moisture, mold, foul odor, and pests than rooms upstairs. It consists of vents that let humid air in and water seepage sources that raise humidity levels. Go for the best basement dehumidifier or dehumidifier for the whole house to eliminate excess moisture.

3. At what dew point does mold grow?

A dew point temperature that is higher than the cold surface in your basement is a potential signal that mold can be growing in your home. Cold surfaces in basements and a high dew point temperature point out to mold growth. Relative humidity of 70 to 80%, a damp environment and high dew point temperature, condensation on windows, are confirmed signs of mold.

4. Will using a dehumidifier get rid of mold?

Yes. Dehumidifiers will effectively maintain the relative humidity level. When the humidity levels of the home are dealt with and moisture removed, you will prevent mold and its issues and effects almost completely. Getting relative humidity monitors and dehumidifiers is a good start against mold.

5. Can mold destroy a house?

Yes. Mold can jeopardize the structural integrity of your home.

6. Can you just paint over mold?

Yes, you can use mold-resistant paint to cover the damage mold has caused, like the darkened patches. But painting over mold DOES NOT KILL mold or resolve the problem. You must remove the growth completely.

7. Is it safe to clean black mold yourself?

You can clean black mold using the right precautions and products. Contact a professional at the first sign of an allergic reaction.

8. What kind of vinegar kills mold?

Regular white distilled vinegar is an effective choice.

Wrapping Up

With this, we have reached the end of the particle. We trust we have a clear idea of the hazards of high relative humidity and mold growth. Share with us your experiences on mold removal and how you protect your home from it.


About The Author

Olivia — a self-confessed air quality addict — is a home climate enthusiast, fresh air advocate, and someone with deep personal experience and knowledge about mold extermination. Her work was mentioned in countless notable humidity publications. Previously she was an editor at Mold Remediation.