What Causes Mold to Grow in a House? Hidden Mold Happens

With good cleaning habits, mold can be kept under control and even prevented altogether. The key is to understand some things about mold. What causes mold to grow in a house?

Mold grows in a house when there is adequate moisture in the air for the mold to flourish. The lack of proper ventilation in a house, as well as water leaks, are common causes of mold, as this encourages a damp and moist environment for mold and mildew to thrive.

What Causes Mold to Grow in a House? Hidden Mold Happens
Mold happens in any house.

Mold grows when there is moisture present, and there are several ways that mold can enter your home.

What Causes Mold to Grow in a House?

Mold can enter your home through the ventilation systems of the bathroom, shower, and kitchen vent.

When mold spores are traveling through the air, they will eventually settle. If mold spores land on a porous, damp surface, they will continue to multiply.

This can be a sink, a kitchen vent, or a mold-infested garbage bag that is not properly disposed of.

It can also occur from water damage due to cracked pipes, excessive humidity from air conditioning units, and the growth of mold on porous materials such as drywall or wood.

In addition, mold spores from outdoor sources such as forests, fields, and gardens settle indoors as well.

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How Can I Know if I Have Mold Growth in My House? 

It can be difficult to tell if mold is growing in your home because mold can grow on walls, floors, ceilings, and other places you don’t notice.

Mold growth will appear as a fuzzy, discolored patch of material that may have an unpleasant odor. Common places to find mold:

  • Behind a refrigerator
  • Around an HVAC and ductwork
  • Walls near leaking windows
  • Mold growth in your shower or bathtub
  • Closets
  • Under sinks
  • Around plumbing
  • Behind furniture that is up against a wall

If you notice any moldy spots, it is important to clean the mold up as well as prevent further mold growth.

If you have mold growing in your home it is important that you also correct the cause of that mold growth.

This is because mold spores will continue to become airborne and float from room to room. Eventually, some spores will land on just the right spot where there is enough moisture and dampness for them to multiply even more.

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How Do I Test for Mold in My House?

If you aren’t sure that you have mold or you want to know the seriousness of your mold problem, you will want to test for mold. How do you test for mold in your house?

You can test for mold by hiring a professional mold inspector or by purchasing a mold kit at your local home improvement store. A professional will take samples of your surfaces, the air, and the dust in your home. These samples are tested in a laboratory, and the test results are provided to you.

Hiring a professional can be expensive. Fortunately, testing for mold in your house doesn’t have to be so costly if you do the testing yourself.

Not only will you save yourself money, but testing for mold is relatively simple to do.

Mold test kits can be found at your local home improvement store or on Amazon. Keep in mind, however, that some test kits are better than others.

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Some things to look out for when shopping for a mold test kit::

  • Mold detection kits can tell you whether mold is present on a surface and what kind of mold it is in minutes.
  • These kits will tell you if there is mold in the air but do not identify the type of mold.
  • Some mold kits include lab fees in the price and some do not

Mold tests work by testing the existence of mold spores in the air. Mold testing kits use this mold spore release to alert you to mold problems inside your home.

Because mold spores are microscopic, mold testing is often done with mold testers that use chemicals like Stachybotrys or ultraviolet light like UV-A or UV-B lights.

Mold testing that uses ultraviolet light enables mold spores to glow.

The mold test kit will turn mold spores into a mold “cloud” that you can see to know when and where there is mold inside your home.

The one drawback of mold testing is that some mold tests only work on specific types of mold.

This means mold testing can be expensive if you have to buy more than one mold test, and mold testing might miss mold spores that the mold test doesn’t recognize.

Remember to go over mold test results with a professional to confirm a mold problem in your home before using any mold removal products or hiring mold remediation services.

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How Do I Get Rid of Mold in My House?

If you’ve found mold in your home, you naturally want to know how to get rid of it to keep it from growing. How do you get rid of mold in your house?

To get rid of mold in your house, use a solution of one cup of bleach to one gallon of water and apply it directly to the affected area with a large sponge. Do not rinse the area after applying the bleach solution. White vinegar may also be applied to the surface, as well as an ammonia and water solution.

If mold is growing inside your house it is important that you clean up mold immediately, especially if mold growth has made you ill.

Even if mold hasn’t yet made you ill yet, the effects of mold do not always become apparent right away, and symptoms of mold can be seen much later on.

Here is what to do when mold grows in your home:

  • Mold removal should start anywhere mold is growing.
  • Since mold grows best in damp environments, mold may be growing behind walls, under floors, or on carpets. Mold cleaning will begin by removing mold from these areas first.
  • Clean any mold that has grown on hard surfaces such as countertops, sinks, toilet seats, moldings, and moldy carpets.
  • After the mold has been cleaned up, you will need to fix the conditions that caused the mold to grow.

Mold will continue to grow and be a problem if the cause is not remedied. Make sure that you are using your ventilation systems when taking hot baths and showers and when cooking.

Environments with a higher level of moisture in the air are a prime breeding ground for mold.

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How Do You Prevent Mold from Growing in Your House?

Before mold grows, it needs a source of moisture to reproduce. Here are some things you can do to prevent mold growth in your home:

  • Fix any sources of water damage such as leaking pipes
  • Keep the humidity level low inside and outside of your house
  • Use mold-resistant materials when building a new house or remodeling an existing one
  • Clean moldy surfaces with soap and water to remove mold
  • Always use ventilation fans when doing things that raise the humidity in a room, such as bathing or preparing meals.

If you have mold growing in your home it is important that you clean up the mold as well as prevent mold growth by fixing mold conditions.

If you have mold allergies, are pregnant, or have a family history of immune system problems, mold infestations in your home can be very unsafe.

What is Black Mold?

Black mold is a type of mold that many people think of and often fear.

They may have heard about black mold poisoning or black mold symptoms, and they likely believe black mold can be dangerous for their health.

However, black mold is not as dangerous as some media outlets make it seem. It has never been scientifically proven that mold which happens to be black is any more unsafe than any other kind of mold.

Black mold is one of many different types of mold that grow on surfaces or in places where there is an excessive amount of moisture.

Most molds are pinkish-gray to black, depending on the species.

Black mold’s appearance comes from the spores that black mold produces; black mold grows and spreads by releasing black-colored spores into the air.

10 Common Places to Find Mold in a House

There are several places where mold can commonly grow inside a house. Let’s take a look at some of those common places:

10 Common Places to Find Mold in a House

  • Closets
  • Bathrooms
  • Kitchen cabinets above the stove
  • Under sinks
  • In corners of the bathroom
  • Walls and ceilings in humid areas
  • Crawlspaces
  • Basements
  • Attics
  • Drywall near a water leak

Mold is a type of fungus that grows in places with high humidity and airflow, and there are places all over your house where mold can grow out of sight.

You can take preventative measures against places where you know water leaks happen by fixing leaky pipes and making efforts to keep the humidity levels down.

Can You Get Sick from Mold in Your House?

Mold has a very bad effect on the human body because mold is a kind of fungus. The mold spores that enter your house can cause mold allergies and mold infections.

Mold allergies are a hypersensitivity to mold, meaning a person will have an adverse reaction from mold exposure.

This type of allergy causes nasal congestion, watery eyes, sneezing, headache, or wheezing attacks after being exposed to mold.

In addition, mold allergies can lead to mold infections such as respiratory illnesses. Mold infections cause fever, chills, fatigue, and pain in the muscles and joints.

If you have mold allergies or a mold infection, it is important to see a healthcare provider right away. Mold allergies can lead to mold infections if left untreated.

If you have mold growth in your home, it is important that you clean up the mold as well as fix any conditions that are causing the mold.


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.