July 21

How to Stop and Prevent Mold in the Home

By Kevin Finn

July 21, 2021

There are a lot of issues homeowners must tend to after a major flood or storm.  Structural concerns, insurance claims, and the health of their family to name a few. Water damage to your home presents many challenges that include the growth of mold. If not taken care of immediately, it can spread throughout your home. 

Excess moisture can increase the risk of mold growth in basements and closets. Mold can also grow on clothing, carpets, food, on and behind walls, pipes, in the ceiling, and almost anywhere moisture can seep into.

Mold can be very destructive to the building structure, eating away at it and causing extensive damage. It is an incredibly serious problem to have in any space and needs to be dealt with quickly and effectively. 

While most people focus on its appearance and smell, exposure to high mold levels can cause allergic reactions and exacerbate symptoms. Some ailments attributed to untreated mold include respiratory difficulties like asthma and pneumonia, rashes, depression, fatigue, digestive problems, and inflammation and pain in the joints.

What Causes Mold?

mold in home

Molds are organisms that grow indoors as well as outdoors. As part of the fungi family, mold releases tiny spores that float through the air. Outside, they’re an important part of the ecosystem. Indoors, the presence of mold can be problematic. 

You’re likely to find mold growing in the darkest and dampest spaces. Certain conditions must be met before mold begins to grow in a home. Moisture is the main factor.

Leaks, spills, and poor ventilation are all common household problems that increase moisture levels. These areas provide the perfect breeding ground for mold spores. When the furniture, carpets, and other materials absorb the water, mold will begin to grow on them as well. Mold can then spread throughout your home within a matter of hours via air ducts or doorways.

Mold grows within 24 to 48 hours after a water intrusion, so you must fix any moisture problems as quickly as possible to prevent its growth. Once it starts growing, mold will continue to feed off your drywall, wooden beams, joists, wallpaper, and carpeting as long as it has a source of moisture.

Other Causes of Moisture

Floods and storms aren’t the only causes of moist environments where mold can grow. Others include:

  • Humidity

    Humidity is the primary cause of mold on walls. Living in the St. Louis area, there are high levels of humidity. An easy solution to reducing the humidity indoors is to purchase a dehumidifier and move it to different rooms regularly. Clean behind your laundry machines regularly. Use exhaust fans or open the windows when you shower in the bathroom or wash dishes in the kitchen, and keep your home well-ventilated.
  • Condensation

    Condensation occurs naturally on the perimeter walls of your home, which are often cooler than the air inside your house. As a result, the water in the air can experience a temperature drop and change state to become liquid. Inspect any outside walls of your house regularly to prevent moisture buildup.
  • Water Leaks

    The third most common cause of mold in residential homes is water leaking. If your pipes drip, water is likely making its way into the framework of your house every time you turn on the tap.As this moisture builds up over time, it becomes a potent hotbed for all kinds of bacteria, and mold becomes inevitable. Check your pipes frequently, and make sure that you take steps to keep them from leaking when the temperature in your area changes.

Preventing Mold Growth

Taking steps to prevent mold growth in the home can go a long way in reducing the need for mold removal. The key to preventing mold is moisture control. Without excessive moisture in your home, mold cannot grow. Below are five tips for stopping and preventing mold growth in your home.

1. Maximize Air Circulation and Ventilation

Keeping the spaces clear around air vents and the HVAC system in your home can increase the airflow. If clutter or furniture is blocking the vents, condensation can form and encourage mold growth. On especially humid days, you may want to add some fans for additional circulation.

Opening a window or installing an exhaust fan in your bathrooms and kitchen can help reduce condensation from forming when showering, bathing, and cooking. Other ways to increase circulation are to open doors between rooms, move furniture away from walls, and open doors to closets that may be colder than the rooms they’re in. Let fresh air in to reduce moisture and keep mold at bay.

Vents to appliances that produce moisture, like clothes dryers and cooking stoves, should be directed outdoors. Using ceiling or free-standing fans within the home can also increase air circulation and keep it drier.

2. Clean Up Water Immediately

If you experience a water leak or flooding, it’s critical to eliminate the excess water within 24-48 hours to reduce the chance of mold spores developing. Use a wet/dry vacuum to clean up as much water as soon as possible. These machines are the most effective tools for removing water. Also, locate the source of water and moisture and handle needed repairs quickly.

Even common everyday occurrences need attention. Don’t leave wet items lying around the house, and make sure to dry the floor and walls after a shower. Don’t leave wet clothes in the washing machine, where mold can spread quickly. Hang them to dry — preferably outside or in areas with good air circulation.

3. Monitor and Control Indoor Humidity

The EPA-recommended humidity level for indoors is between 30 and 60 percent. You can purchase moisture meters from a hardware store to measure indoor moisture levels. 

Using dehumidifiers can help reduce indoor humidity by removing any moisture from the air that you aren’t able to prevent and will help you control the humidity in the house. It’s particularly important to have dehumidifiers in damp areas, such as basements and crawl spaces.

4. Check Furniture and Flooring

Look for water damage and remove furniture from wet flooring. Remove damaged materials, furniture, and carpet if they can’t be cleaned or restored. You can always replace these items once your home is back to normal. 

5. Sanitize and Clean

All items affected by floodwater should be cleaned and sanitized. Clean all walls, hard-surface floors, and household surfaces with soap and water. Sanitize and deodorize all carpets by having them steam cleaned.

Common Problem Areas For Mold Growth

You can do a walkthrough of your home to identify potential mold problem areas like:

  • Basement flooding
  • Condensation on windows
  • Water stains on ceilings
  • Damaged or clogged gutters
  • Damp carpets
  • Leaking pipes
  • Moisture around sinks, toilets, and tubs
  • Musty odors, especially in basements and attics

Focus Areas for Stopping Mold Growth

Below are some additional steps to take to stop and prevent mold growth in your home.


  1. Control moisture. Keep the humidity level under 60 percent.
  2. Dry up wet materials quickly. It only takes mold two days to grow.
  3. Clean, disinfect, and dry surfaces prone to mold growth.
  4. Repair leaks. Replace dilapidated old pipes. Fix leaks on the roof, walls, and foundation of the house. Unclog HVAC units and drain regularly.
  5. Dry items thoroughly before storing them.
  6. Improve airflow at home. Start with opening closet doors more frequently and moving furniture far from walls to provide better ventilation to confined spaces. The more windows you can open, the better.
  7. Monitor your basement’s ventilation. Set up a foundation drain, put in a dehumidifier, insulate walls, set up a thermal plane, and let the entire room dry.


Walls are a very common area for mold to grow, especially in damp environments such as basements, washrooms, and laundry rooms. Another common occurrence is mold growing behind your walls. Mold can also grow behind wallpaper, as the glue can often absorb moisture and produce mold.

  1. Mold on the walls can spread to adjacent areas, such as the carpet or other items. Move these away from the walls and salvage whatever you can.
  2. Use a mixture of one part bleach and three parts water and scrub the wall with a heavy-duty sponge or scrub brush. Let the solution soak in for a few minutes. Turn on the ventilation fan.
  3. Allow the walls to dry completely.


  1. Remove and replace sealant or caulking affected by mold.
  2. Use effective mold-killing chemicals to clean your bathrooms. Keep your bathroom doors and windows open while cleaning. This should help dry up the bathroom.
  3. Invest in an effective exhaust fan for every bathroom at home. Vents can suck out the moisture in your bathroom and send it outside. Use the fan properly. Turn the vent on during a bath or shower and leave it on for an additional 30 minutes after leaving the bathroom. You can purchase a fan with a timer for your convenience.
  4. Make it a habit to dry up the shower walls or tub with a squeegee.
  5. Once you notice leaks, fix them right away. Delaying repairs will only encourage mold to grow and take hold.
  6. Dry out everything in the bathroom. After using your sponges, loofahs, and product bottles, remove them from the shower and let them dry.
  7. Wash towels, rugs, and mats regularly.


  1. Look for mold way beyond the visible surfaces because they tend to spread farther than the exposed parts.
  2. Remove bags, boxes, and other items in the area, especially those that have come in contact with the mold.
  3. Remove carpets and other flooring materials that you suspect are affected by mold.
  4. Use a mild cleaning solution and scrub the surfaces.  Use brushes on hard-to-reach spots.
  5. Rinse the scrubbed surfaces well and let them dry.
  6. Proper ventilation of your basement is also key to preventing mold growth. Keeping windows open is one way to keep your basement properly ventilated. Purchasing a basement dehumidifier is one of the most effective ways to stop mold from growing in your basement.
  7. If getting air circulated in the basement is a problem, think about buying an air mover to maintain proper ventilation in the basement.
  8. Once the basement is dry, repair and redecorate it with new flooring and insulation.


  1. Check for leaks in the crawl space ceiling and walls, especially the plumbing components and HVAC ducts.
  2. Downspouts and gutters should push water away from the foundation of the house to prevent water from flowing into the crawl space.
  3. Provide proper ventilation in the space.
  4. Insulate the space floor and foundation walls with plastic sheeting. Check the insulation bi-annually or annually for any water problems.
  5. Dryer vents should release air outside and not into your crawl space to prevent humidity readings in the area from increasing beyond the 30 to 50% level.


  1. Open the windows closest to the affected closet before laying a tarp or other protective layer on your closet floor.
  2. Spray water onto the affected areas of the closet to stop spores from going airborne.
  3. Prepare a bucket full of warm water with mild dish-washing soap. Scrub the closet mold down with a stiff brush dipped in the cleaning solution. Rinse affected areas.
  4. Dry up all the closet surfaces.  Leave the windows and doors open for more thorough drying.


  1. Vacuum the affected area to remove loose spores.
  2. Use warm water and soap on stained or painted wood. Use bleach on raw wood. You may also use vinegar to soften the mold.
  3. Sand the recently cleaned area to get rid of any residual mold. You can refinish it afterward to prevent mold from coming back.
  4. Control moisture content in wood. If it's already wet,  kiln drying will help keep the wood dry and mold resistant.
  5. Use appropriate chemical treatments to effectively kill and prevent mold spores from growing.

Immediate Action Prevents Mold from Spreading Further

There are signs you can look for to determine if you’ve already got mold growing in your home. If you notice any of these signs, it can be dangerous to try to remediate them yourself.

Once mold becomes visible to the naked eye, it has likely already caused more damage than the typical homeowner can fix. Contact with mold can be very dangerous unless you have the proper equipment, experience, and knowledge, and the appropriate gear to remediate it.

If you believe you have mold growing in your home, call the professionals at St. Louis Cleaning and Restoration as soon as possible. We are available 24/7 for emergencies to help prevent further devastation to your home and health.

We have been serving St. Louis families, businesses, and corporations since 1991 as a local family-owned company. Our mission is to exceed our client’s expectations and provide fair and honest pricing, quality service, innovative technology, and unprecedented customer service.

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