What Humidity Does Mold Grow?

Simple Answer: According to moldtesters561.com, a humidity level above 55% to 60% can lead to the growth of mold. If the humidity levels are above 70% (water or moisture being present), you can see mold growth in some hours.Similarly, if your building material is saturated (20% or more), mold can grow in your property. 

Mold can grow anywhere that has high levels of humidity. It is a natural process, but it can also indicate other problems in your home. Mold spores are everywhere, and the only way to avoid them is to eliminate all indoor moisture sources. Keep in mind that humidity level plays a major role in mold’s ability to grow and the speed at which it does so.

This article will go over exactly on what humidity makes molds grow, how you can tell if you have an issue, and what solutions there are for getting rid of it forever!

Relative Humidity and Mold on cold surfaces

When a high level of humidity hits the cold surfaces, it will cause water droplets that result in mold growth. For example, if you have been away from your home for some days, the mold might be welcome when you return. It can even form when you accidentally leave your AC on.

To avoid this, you can keep the cold surfaces dry by using a dehumidifier. You should also make sure that your home is well insulated and has proper ventilation to balance the humidity levels.

What Humidity Does Mold Grow?

When the humidity level is above 55 to 60%, mold can grow. If it is above 70%, it can grow within 24 hours of water or moisture being present. Condensation can also occur as a result of elevated relative humidity. When humid air comes into touch with a cold surface, it may produce moisture or condensation.

Mold is often found in bathrooms and basements due to high humidity levels from showers, baths, sinks, toilets, etc.

If you find mold on your ceiling or walls, you need to realize that humidity levels in your home are extremely high, and they will most likely continue growing.

In Boca Raton, the average humidity level is 72%. This high humidity can cause many problems for people with allergies and asthma. It also creates an environment that is perfect for mold growth. So, for mold inspection in Boca Raton, you can contact us anytime!

At What Humidity Level Does Black Mold Start to Grow?

Black mold, also known as Stachybotrys chartarum, is a type of toxic mold that can start to grow at humidity levels above 60%. It needs high levels of moisture to grow, and it often grows on materials that are damp or have been water damaged.

Black mold produces mycotoxins, which are poisonous compounds. If you are exposed to them, it can cause several health problems, including asthma, respiratory problems, and even death.

If you think that you may have black mold in your home, it is best to get it tested by a professional. You can also test the humidity levels in your home with a hygrometer to see if they are too high.

How to Tell if You Have an Issue?

The best way to determine whether or not you have a mold issue is to perform a visual inspection. Look for black, green, or brown patches on walls, ceilings, floors, and furniture. If you see any of these colors, you likely have a mold problem.

You can also use a hygrometer to measure the humidity levels in your home. This device will give you an accurate reading of the relative humidity.

What Can You Do to Reduce the Humidity in Your Home?

There are a few things that you can do to reduce the humidity levels in your home and help prevent mold growth:

  • Use a dehumidifier to remove moisture from the air.
  • Make sure that all of your appliances and fixtures are properly vented.
  • Fix any leaks or water damage that may be present.
  • Keep your home clean and free of clutter, creating a humid environment.
  • Open windows and doors to allow air to circulate.


Hopefully, this article has given you a better understanding of what humidity mold grows. There are some simple steps that you can take to reduce the risk of moisture in your home and prevent black mold from growing. Moreover, if you are looking for professional mold testers, Moldtesters561 is here to help. Give us a call today!


how much humidity can grow moldQ: Will mold grow at 55 humidity?

A: Mold will not grow at 55% humidity, but it can still spread. The higher the humidity level, the faster mold will grow.

Q: Can I use a humidifier to prevent mold growth?

A: You can use a humidifier to help control the humidity levels in your home, but you cannot rely on it to stop growth. The best way to ensure that you have a mold-free home is by eliminating the humidity source, which means no showers, baths, sinks, toilets, etc.

Q: What humidity level kills mold?

A: Mold can grow in any humidity level above 60%, but it will not spread if the levels are under 30 to 40%.

Q: Does high humidity cause black mold?

A: High humidity can lead to condensation and an increased risk of moisture damage in homes with elevated levels of molds. The presence of black mold is not indicative of high humidity, but it can signify that you have a moisture problem.

Q: How do I get rid of the mold if the source of humidity is still present?

A: If the source of humidity cannot be eliminated, you will need to treat the areas where mold has already developed. It can be done using a commercial mold killer or a household cleaner. You can also hire professional mold testers to get rid of mold permanently.