13 Hidden Signs Of Mold in Your House

Most people think that they don’t encounter mold on an everyday basis. In reality, mold is everywhere – on the street, in your office, in your local supermarket, and your home.

Unfortunately, you can’t always see mold. But you can use the clues your house gives to investigate and find mold-infected areas. 

We’ve collected 13 easy-to-notice signs that mold might be spreading through your house based on data from the EPA, the CDC, and our own professional experience.

Because mold spreads through spores that travel in the air, it is normal to have a certain level of it present in our environment. Usually, mold spore count in our home equals that of the surrounding outside air. 

However, when the levels of mold inside exceed the norm, it can not only cause discomfort but also health problems in humans and even pets. Mycotoxins, produced by some species of fungi (mold), can annoy you with something as small as a runny nose, but if exposure continues, or your immune system is compromised, it can lead to serious health problems or even death.

#1: Existing Stains That Might Actually Be Mold

“Isn’t it easy to spot mold growing on a surface? How could you miss it?” you might ask. Actually, growing mold is often overlooked. Mold isn’t always obvious, and it is easy to misinterpret it as “dirt around the sink” or “an old basement stain” that just wouldn’t come off. 

Take a closer look at a potential infestation area, as that might be a sign of growing mold in your house. If this affected area becomes larger over time – it is most likely mold. 

Run a quick test: take a cotton swab, soak it in a mixture of bleach and water (1 part bleach, 16 parts water), and apply to the stain. If the spot where you applied it quickly becomes lighter or if the color comes back after – it is mold.

#2: Your Bathroom Grout Turns Dark

Have you noticed that the grout between your bathroom tiles is darker than it was originally? That could mean that the water vapor, after you shower, doesn’t have a way out of the room. 

If you don’t see additional mold growth – that’s the good news. You can easily remove mold from your shower grout with different DIY methods. But if you have a bigger problem outside of the shower, you might not want to deal with that yourself. 

If mold isn’t handled well, it can release spores into the air, which can cause mold growth in new places and even health issues.

To prevent moisture from building up in your bathroom, run the exhaust fan for 30 minutes after you shower, wipe down the walls in the shower (especially grout), and leave doors and windows open for some time.

#3: High Humidity Levels

There is nothing as annoying as dry air that makes your nose bleed, your eyes water, and dries out your skin. That’s why humidifiers help us feel better, providing that healing moisture. 

But uncontrolled humidity levels might hurt you more than dry air itself. According to the CDC, indoor humidity should not exceed 50% to prevent excessive mold growth. 

High moisture levels, oxygen, and a place to grow on is everything that indoor mold needs. And, damp drywall behind your sink fits all the criteria.

#4: Your House Smells Musty

One of the signs of hidden mold in your house can be the odor. 

During the different stages of mold growth, it releases smelly compounds called mVOCs. When your house smells musty or earthy, it might indicate that your home is growing mold, and you need to find the source of that smell. 

According to the EPA, it is unknown if mVOCs (the smelly compounds, not the mold itself) causes health issues. We didn’t test this on our health, and you probably don’t want to either. If you find any mold in your house, remove it as soon as possible.

#5: Flu-like Symptoms Never End

The fact that mold can cause health issues is widely known. Often, these symptoms resemble the common cold or flu. Your never-ending battle against headaches, runny nose, and sneezing might be a sign of an elevated level of mold spores in the house. 

If the flu-like symptoms linger more than usual, you should contact professional mold remediators to measure the level of airborne mold inside your house. Typically, you will get the report within 3-5 days, along with suggestions of necessary steps to eliminate mold.

#6: Seasonal Allergies Don’t Stop

If your seasonal allergies just don’t stop or become worse when you’re home, this might suggest that your house has a mold issue. 

People with allergies are more susceptible to developing a mold-related illness, so it is important to find and remove the source of the problem. If you can’t see mold, check your air quality. Airborne mold is invisible, yet still dangerous, especially for people with asthma or allergies.

You can hire a local mold removal company, or you can test the air yourself.

#7: Your Asthma is Getting Worse at Home

If you’re experiencing more asthmatic symptoms while at home than outside – you need to check your home for mold. Mold contributes to and worsens asthma, and it has also been linked to developing asthma in those who didn’t have it before. 

As with any health issue, talk with your doctor and consider hiring a mold testing company to find and professionally remove mold from your house.

#8: Your Plumbing Is Leaking

How long has it been since you checked the condition of the sink or toilet pipes? We recommend checking them at least twice a month. 

If you notice rust, leakage, or condensation on pipes, this is a sure warning that if you don’t fix it and its damage (if there’s any), you will see mold grow there pretty quickly. 

Both the EPA and the CDC recommend drying out any wet or damp area within 24-48 hours after the incident to prevent mold growth.

#9: History of Flooding in The House

If your house or basement has been flooded, most likely, it will develop some mold.

Responding quickly to water damage is the key. In case you noticed the damage too late or didn’t dry it out completely, mold will start spreading and might cause a variety of health issues. 

Treat any current or past flooding as an early sign of mold in the house. If you notice mold, contact a professional mold remediator to remove mold from your home environment.

#10: Condensation Builds Up

As winter approaches, you may notice another sign of mold in your house – condensation. This word should scare homeowners, as it can not only help mold development, but it can also damage your house. 

Condensation occurs when warm air contacts the cold surface, then the water in the air changes its state from vapor to liquid. Condensation most commonly occurs on windows, basement walls, or in a garage when it’s cold outside.

If the condensation isn’t taken care of, it will start dripping and make the floors, windowsills, or walls wet. That creates a pleasant environment for mold growth. 

You might want to turn down your humidifier or let the air circulate through your house by opening windows often to avoid condensation.

#11: Your Wallpaper Is Peeling or Bubbling

Besides hurting your health, mold can also damage your house. It loves to eat on cellulose-rich materials, so drywall and wallpaper are mold’s favorite meals. 

If you suspect that mold hides in your home, look at your wallpaper. Mold growth can cause unnatural peeling or bubbling on your walls. Dark stains on your wallpaper can also be a sign of mold.

React quickly if your walls become wet for whatever reason. You don’t want it to stay that way for over 12 hours, as that can be enough for mold to start growing.

#12: Your Air Conditioning Smells Weird

If you turn on the air conditioning, and it has a funky smell, this is yet another sign that you have mold in the house. 

You might have heard that air conditioning helps you prevent mold, and that’s true. But when these systems (HVAC) are turned off, they create perfect conditions for mold growth, as they’re warm, damp, and dark. 

To minimize the risk for your family and the rest of the house, don’t use the air conditioning if you suspect mold until remediated or a professional confirmed its absence.

Moldy air conditioning can quickly spread mold spores throughout the house, which can cause other areas to develop mold growth. 

According to the EPA, mold-infected HVAC systems should be treated by professionals only.

#13: Your Skin Is Dry and Itchy

Yes, that’s right! Your clothes can grow mold, and it can irritate your skin, making it dry and itchy.

Whether it be in your closet, a laundry bag, or clothes washer, if you leave clothes damp, it will create opportunities for mold to grow. Make sure to dry out your bathroom towel or clothes after getting them wet. 

Ventilate your bathroom to reduce excess moisture that can cause mold growth on your clothes or in your home.

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Who is Jeff Neeley?

Jeff Neeley is an industry expert and the trusted authority in mold remediation in Nebraska. As the owner and CEO of Pure Maintenance Mold Removal in Nebraska since August 2019, Jeff has amassed a wealth of experience and expertise in tackling mold-related issues. With an unwavering commitment to safety and effectiveness, he has successfully treated hundreds of homes, ensuring the well-being of both occupants and their beloved pets. Jeff's comprehensive approach leaves no room for compromise, as he meticulously addresses every aspect of mold removal to deliver exceptional results.