Why Does My House Smell Like Mildew? Causes and Preventions

Mold can be a serious problem in many homes, leading to unpleasant odors and health hazards if left untreated. If your home is experiencing a musty or mildewy smell, it could be due to mold growth in your basement or other damp areas.

To address this issue and prevent further problems, it is important to identify the source of the odor and take steps to remove the mold. This may involve cleaning surfaces, removing waterlogged items, installing dehumidifiers and fans, and more.

Why does my house smell like mildew? Lady spraying air freshener

With proper care and attention, you can restore your home back to its fresh and clean state and keep it smelling fresh for years to come.

Indoor relative humidity (RH) should be kept below 60%, ideally between 30% and 50%, if possible. Low humidy discourages the growth of mold and mildew.


Why Does My House Smell Like Mildew?

In this article, we will be discussing why houses sometimes smell like mildew and how to remove the smell if it is present in your home. We will also be outlining some prevention tips to keep your home smelling fresh.

Mildew can form when there is moisture present in the air combined with a lack of ventilation. This can be a problem in bathrooms, kitchens, and rooms where moisture is commonly present.

Mold and mildew can also grow in areas where there is water damage or leaks, such as around windows or in basements.

If you suspect that you have a mildew problem in your home, it is important to identify the source of the smell and take steps to remove it.

According to the CDC, mildew exposure can cause health problems, so it is important to take action quickly if you notice a mildew smell in your home.

Removing the mildew smell from your house can be a challenging task, but it is important to take action if you are concerned about the health risks associated with mold and mildew exposure.

By following the tips below, you can successfully remove the smell of mildew and keep your home smelling fresh.

The most common challenge people have when trying to remove the mildew smell from their house is knowing where to start.

There are many methods you can use, and it can be difficult to know which one will work best for your situation.

Another challenge people face is getting rid of the smell permanently. If you only take steps to temporarily cover up the smell, it might come back later.

It is important to identify and remove the source of the mildew if you want to keep your home smelling fresh.

If you have a severe mildew problem, it might be necessary to hire a professional to help you get rid of the smell.

Talk to your local hardware store or cleaning service for recommendations on how to best address the mildew odor in your home.

How to Remove Mold Smell from a House

Mold can be a major nuisance in your home, causing unpleasant odors and potentially damaging your property. If you are struggling with mold smell in your house, there are several steps that you can take to get rid of it and restore the freshness of your space.

With some time, care, and perseverance, you can successfully remove mold smell from your house and protect your home against future growth.

Step 1. Follow Your Nose

As they say, the nose knows. Start your inspection in the areas of your home where the mildew smell is the strongest. Be mindful of other locations in the home where the mildew smell could be coming from, such as a basement that you may not visit often.

Step 2. Address Moisture Issues

Address any existing moisture issues, such as leaks, condensation, and excess humidity or dampness in your house. Pay particular attention to possible hidden leaks underneath sinks and behind toilets.

Practicing ways to maintain a healthy and safe humidity level is key in this whole process. Once you get a handle on controlling the humidity levels, you can then address cleaning up the mold and mildew mess it left behind.

Start better habits by doing the following:

  • If you live in a humid climate, running your AC pulls moisture out of the air in your home, lowering your relative humidity.
  • Invest in a dehumidifier. You may need more than one if your house is relatively large. Dehumidifiers allow you to be in control of the humidity level in your home. A humidity level of 50% is ideal and will prevent the growth of mold and mildew.
  • Run fans and open windows during and after hot baths and showers.
  • Ensure that your dryer vent is venting to the outside of your home.
  • When cooking, run the exhaust fan.

Doing what you can to prevent the accumulation of excessive moisture in the air will discourage more mold from returning.

Step 3. Inspect Your Attic, Crawl Space, and Gutters

When was the last time you were in your attic or your crawl space? Roof leaks can go unnoticed for a very long time. Pipe leaks inside walls can also go unnoticed. If you see a random patch of mold on a wall, you may very well have a pipe leak.

Clogged gutters can cause a backup of water that eventually finds its way inside your home. Routine gutter maintenance is highly recommended.

Step 4. Time to Scrub

Using white vinegar or hydrogen peroxide (3%) in a spray bottle, saturate the area you wish to clean. While wearing cleaning gloves, scrub the affected area with a scrub brush, repeating if necessary.

The odor of vinegar goes away after it dries with proper indoor ventilation. Vinegar is also a natural order neutralizer, so it will help you get rid of the mildew smell.

With the practice of keeping your humidity levels no higher than 50% and proper ventilation, you’re sure to get a grip on the mildew that was once out of control.

You can also purchase a hygrometer at your local hardware store. Hygrometers are small handheld instruments that measure the humidity in the air to help you control moisture levels with a dehumidifier or AC if needed.

About 40% of asthma episodes are triggered by the household presences of mold, dust mites, or rats.

Center For American Progress, 2016

Causes of Musty Smell in a House

A mildew smell in a house can be caused by a number of factors, including dampness, poor ventilation, and mold growth. Dampness is often the culprit in musty basements or crawlspaces, as these areas are typically poorly ventilated and prone to moisture buildup.

In addition, any area of the house that has had water damage is also at risk of developing a musty smell. This is because mold and mildew can grow in damp, humid conditions, and these fungi release spores that can cause an unpleasant odor.

Musty, mildewy smells can also be caused by tobacco smoke, pets, or even certain types of cleaning products.

To eliminate an offensive smell, it is important to identify the source of the problem and take steps to address it. In some cases, this may involve simple measures like opening windows or using a dehumidifier.

Possible causes of that mildewy, musty smell in your house:

Mold and Mildew

The most common cause of musty smells in a house is mold or mildew growth, which can occur both indoors and outdoors.

Water Damage

Another possible cause of musty odors is water damage, which may be the result of a leaky roof, a flooded basement, or any other source of moisture intrusion.

Poor Ventilation

Poor ventilation or air circulation can also contribute to the development of musty smells in a house, particularly in areas that are prone to high humidity levels or periods of condensation.

Dampness and Humidity

Along with poor ventilation, dampness and humidity can create the ideal conditions for mold and mildew growth, leading to an accumulation of mildewy odors over time.

Clutter and Dirty Surfaces

Clutter and unclean surfaces can also contribute to the development of musty smells, as they prevent air from circulating freely throughout the house and allow moisture to accumulate in certain areas.

Outdoor Pollutants

Outdoor pollutants like exhaust fumes or industrial emissions can be carried indoors on wind currents, resulting in musty smells that seem to come out of nowhere despite having no actual source inside the home.

The Health Risks Associated with Mildew Exposure

Many people are unaware of the health risks associated with exposure to mildew. While it is commonly thought of as nothing more than a nuisance, mildew can actually cause a range of health problems, from respiratory issues to skin irritation.

In some cases, exposure to mildew can also lead to serious infections. For example, people with weakened immune systems may be at risk for developing pneumonia if they inhale high levels of mold spores.

In addition, children and the elderly are also more susceptible to the ill effects of mildew exposure.

That’s why it’s important to take steps to prevent mold growth in your home and to seek medical attention if you believe you’ve been exposed.

By understanding the risks associated with mildew, you can help keep yourself and your family safe from its harmful effects.

Common Symptoms of Mildew Exposure

The symptoms of mildew exposure from inhaling mold spores or skin contact may include:

  • Sneezing
  • Coughing
  • Wheezing
  • Watery eyes
  • Runny nose
  • Skin irritation
  • Fatigue
  • Headache

Those with asthma or other respiratory illnesses are likely to suffer more severe symptoms such as difficulty breathing, wheezing, and coughing up bloody phlegm.

Why Does My AC Smell Musty?

Air conditioners circulate cold air throughout your home, and in the process, they also circulate any mold or mildew that may be present. As the air conditioning unit pulls in warm, humid air from your home, the colder temperatures inside the unit cause the water vapor in the air to condense.

This creates an ideal environment for mold and mildew to grow. In addition, dirt and dust can accumulate on the coils of the air conditioner, providing a food source for mold.

As mold and mildew grow, they release spores into the air, which can cause musty odors.

If you notice a musty smell coming from your AC unit, it’s important to clean the coils and change the filters to prevent further growth.

Why Does My Bathroom Smell Musty?

Your bathroom may smell musty due to the presence of mold or mildew growing somewhere in the room. This is most likely to occur in areas that are warm and humid, such as around the shower or toilet.

Another possibility is that the drain is partially blocked, causing water to build up and creating an ideal environment for bacteria to thrive.

If you notice a musty smell coming from your bathroom, it’s important to take action right away. Left untreated, these problems can lead to serious health risks.

Fortunately, there are a few simple steps you can take to eliminate the source of the odor and keep your bathroom smelling fresh and clean.

Why Does My Basement Smell Musty?

When you notice a musty smell in your basement, it’s a sign that mold or mildew is present. Both mold and mildew thrive in damp, dark environments, so basements are a common target. The first step in getting rid of the problem is to find the source of the moisture.

If you have a water leak or high humidity levels, address those issues first. Once the environment is no longer conducive to mold growth, you can clean up any existing mold with a bleach solution.

To prevent musty smells from returning, be sure to keep your basement dry and well-ventilated. Installing a dehumidifier can also help to keep mold and mildew at bay.

Water Leak Smell

Water leaks are usually accompanied by mold and mildew problems. When water leaks behind walls or beneath floors, it creates the perfect environment for mold and mildew to grow. These fungi thrive in damp, dark places, and they can spread quickly through a home or office building.

In addition to causing musty odors, mold and mildew can also cause health problems, particularly for people with allergies or respiratory problems. If you suspect that you have a water leak, it’s important to fix it as soon as possible to prevent the growth of mold and mildew.


By keeping a home’s humidity levels between 30-50%, mold and mildew will not feel welcome, and will pack their bags and leave town. Finding and resolving the source of the mildew smell in a house sets the stage for a dryer, mildew-free home moving forward.


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.