Signs of a Mold Problem

Signs of a Mold Problem

Signs of a Mold Problem

22 signs that you may have a potential mold problem in your home or building.

1. High Humidity

If you live in an area with high humidity, then you should always be on the lookout for potential mold problems. Naturally, the outdoor humidity affect indoor humidity levels, creating a perfect environment for toxic mold growth.

A relative humidity (RH) level of greater than 55% promotes the growth of mold and other fungi. (more about relative humidity). Although relative humidity remains fairly consistent outdoors, it fluctuates drastically inside as a result of being altered by the artificial heating and cooling (i.e. climate control by the HVAC system). 

In which case, it is critical to closely monitor the relative humidity level in various parts of your home or building, since relative humidity can also vary from room to room. (Relative Humidity Sensor Buying Guide).

In addition to using humidity sensors to monitor the moisture level, you can also run dehumidifiers and employ other products and methods to control humidity in the home or building.

Controlling Humidity in the Home

What to look for in a Dehumidifier

2. Water/Pipe Leaks

Mold needs moisture in order to grow and thrive. Many mold problems originate as a result of some kind of water intrusion, especially those that are not resolved quickly. In which case, water and pipe leaks are common culprits, since they provide plenty of moisture, and are often undetected for days, months, or even years if minor enough.

When leaks are discovered, appropriate steps are not normally taken to minimize potential mold growth problems (Mold Problem Prevention Tips).

By the time they are discovered, it is often too late, since the mold will have had ample opportunity to grow in the same hard-to-find places where water leaks occur, such as in wall cavities (Mold Clean Up Tips).

Signs of a Leaking Pipe

3. Flooding

Mold problems are very common after flooding for obvious reasons (plenty of moisture which is conducive for mold growth). Plus, it usually requires several days or weeks to fully dry out the home or building once flooding occurs, giving colonies of black mold more than adequate time to become fully ingrained in these sections.

4. Mildewy/Musty Odors

Odors can often be the first or only sign of a potential mold problem, since mold commonly propagates in places not normally in view. This does not necessarily mean that you definitely have a mold problem, but it should prompt you to look for the other signs, or to look for the mold growth itself (How to Find Mold).

In some cases, mildewy smells will only be evident when the air conditioning or heat is turned on, or it may just be much more evident when the HVAC system is running. If this is the case, then it is very possible that you have significant mold growth within the HVAC system.

5. Increased Allergy/Respiratory Symptoms

If one or more people living in a house, or working in a building (especially if it is an unusually high percentage of occupants) begin suffering allergic reactions that seem to be associated with your home or building, then it could be due to the presence of high levels of mold, especially if other signs are also present.

This may mean that people began experiencing much more allergic and respiratory-related symptoms after moving into a home, or after beginning to work in a building.

Remember, that according to a 1999 Mayo Clinic study, nearly all chronic sinus infections (afflicting about 37 million Americans) are a result of mold.

Health Effects of Mold

6. Signs of Toxic Poisoning

Toxic black mold and other fungi produce Volatile Organic Compounds (VOCs) during the process of degrading substances to obtain nutrition.  The VOCs are the cause of the typical “moldy/musty” commonly associated with fungal contamination indoors.  Exposure to high levels of VOCs may irritate the mucous membranes and the central nervous system leading to symptoms of headaches, decreased attention span, difficulty in concentration, and dizziness.

Health Effects of Mold

7. Leaky Roof

Like other types of water leaks, water intrusion through the roof is difficult to find until it is too late. If you suspect a leaky roof, check in the attic for signs of water damage or mold growth. Also be on the lookout for signs of water damage or mold growth in ceilings on the uppermost floor of the home.

Preventing Leak Roofs

8. Use of Humidifiers without Relative Humidity Control

Using humidifiers can easily raise the moisture level in the air to the point where mold is able to grow at a rapid rate. When using a humidifier, the key is to regulate the relative humidity level, to ensure it stays within 55-60% RH.

This can be accomplished with a relative humidity sensor. However, if you are using a humidifier, it is best to have one that can be programmed to automatically shut off when relative humidity reaches 60%, such as the SuperAire humidifier (with built in relative humidity sensors) by

9. Damp Basements or Crawl Spaces

Basements and crawl spaces tend to receive less ventilation (especially crawl spaces), while also seeing cooler temperatures. With all things being equal, cooler temperatures will lead to a higher relative humidity percentage, since cooler air is able to hold less water before condensation occurs. Of course condensation means moisture. 

In addition to all of this, basements and crawl spaces are more likely to be neglected than other parts of the home, so mold can grow undeterred for a longer period of time.

Also, water from leaks in the home will eventually make its way down to the lowest areas, thanks to gravity.

Finding Mold in Basements/Crawl Spaces
Preventing Mold Problems in Basements/Crawl Spaces

10. Condensation or Rusting

Condensation on or around pipes, windows, or walls is a sign of a leak or high humidity. Rusting on pipes in particular, and anything else metal, is also a sign of a high humidity problem or nearby leak.

11. Lots of House Plants

House plants require consistent watering, which increases moisture levels inside.

12. Discoloration of Walls (Water Stains)

Yellowish stains on walls and ceilings are a sign of excessive moisture. In more obvious cases, where mold growth may already be in full swing, the wall or ceiling may have a greenish, brownish, or blackish discoloration to it. 

You may also notice places where the paint is coming off due to moisture, or where it is "bowing" out.

One way to check for mold growth is to move a medical grade, flourescent tube ("black light") around walls, ceilings, and even carpets while it is dark. A yellow glow is a sign of mold growth.

Preventing Excessive Moisture in Walls

13. Cracked, Peeling Paint

This usually means that there is moisture build up behind the paint. By the time the paint shows these signs, the moisture has often had an opportunity to spawn the growth of mold within the wall.

14. Blocked Gutters

Gutters that are blocked can cause water to seep into walls, through the roof, and can cause water to collect at the base of the foundation, which will result in further water damage in the home or building.

Preventing Blocked Gutters

15. Warped Wood

Naturally, moisture is going to cause wood to warp. If wooden materials in your home have been infiltrated by enough water to actually warp, then sufficient levels of moisture are probably present to accelerate mold growth.

16. Black Growth in Bathroom Tiles

Bathrooms are a favorite breeding ground of mold. The increased moisture and common presence of tile in bathrooms are each highly conducive to the proliferation of mold colonies. 

Tile grout is porous and will allow water penetration, and behind the tiles themselves. In addition, dirt and other grime (favorite foods of mold) are easily trapped in the grout. This combination creates an ideal environment for mold to thrive. 

Even if some type of sealant is applied, tiles expand and contract, and pieces of grout will eventually break off, compromising the seal. (preventing mold growth in tiles/bathroom)

17. Loosening of Drywall Tape

This is a sure sign that moisture has infiltrated the wall.

18. Visible Biological/Mold Growth

This may seem like an obvious sign, but many people do not take a little visible mold growth very seriously. However, this can be an indication of a much larger mold growth in less visible places.

Mold can take on a variety of appearances, such as black, grey-brown, grey-green, white & orange spots, or even pink or purple splotches if growing behind vinyl wallpaper. Stachybotrys is commonly a dark, slimy, greenish-black mold.

Some of the more common locations where mold is found inside includes in bathroom tile, basements/crawl spaces, and other damp and/or dark areas.

How you know if what you’ve found is Mold

19. Clothes Dryers/Other Appliances Not Vented Outdoors

If the steam from these types of appliances is vented inside, then this significant amount of additional moisture creates a great environment for mold to flourish.

Properly Venting Combustion Appliances

20. Poor Ventilation

If the air pressure in your home is "negative", meaning the air pressure outside is greater than it is inside, then it will force moisture and contaminates back into the home. If the air pressure is well into the "positive" side, then it can cause moisture to be forced into walls. The air pressure in your home should be slightly positive, or at least balanced.

Ensuring Proper Ventilation

21. Presence of Wet Materials Indoors

This can include rags, steam from cooking, indoor clothes lines, carpet, or furniture. If these or other items are damp for extended periods of time, then the moisture level can be high enough to accommodate mold growth.

22. Mold Test

There are a variety of sampling techniques that can be used to help determine whether or not you have excessive levels of mold. There are mold tests that take samples from the air, and some that take samples from surfaces. Each method has its advantages and disadvantages. 

Mold tests by themselves cannot give you the full picture, but when combined with other evaluation methods (such as those listed on this page) you can better determine the extent of the problem.

Since they can be expensive, and usually tell you only what you already know, it is usually best to find the source of excessive moisture and to try fixing it before resorting to a mold test.

Some techniques identify what species of molds are present. This can be helpful since some mold species pose a greater health risk than others.

(Mold Test Review)

All in all, you are generally better off tracking relative humidity, since a relative humidity level of 55% or greater usually means that you will have indoor mold growth (Relative Humidity Sensor Buying Guide).

What’s Next?

If the signs point to a mold problem, then the next step is to Find the Mold Growth, so it can be cleaned and removed.

You should also start employing methods to Prevent further Mold Growth (prevent it as much as humanly possible anyway).

How to Find Mold – Where to look and ways to uncover mold growth in your home or building.

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