How to Find Mold

According to a recent study conducted at the University of Arizona, mold can be found in at least four areas of every home in America. Since moisture is required for mold spores to grow, you need to be aware of places in your home that are frequently damp.

Attention to the areas to the right can help you rid your home of mold

Inside Cabinets

Any place that is dark, and where moisture can accumulate, is a potential breeding ground for mold.

Beneath Drywall

When mold grows within wall cavities (which it often does) the nearby drywall is usually infected as well. If toxic mold does become engrained in the drywall, it should be replaced (after the mold is cleaned up and the source of excessive moisture is resolved).

If your walls show signs of mold (cracked/peeling paint, bulging behind the paint, discoloration of walls), then that section of drywall should be torn out and inspected. If the drywall is determined to have mold (How you know if what you’ve found is Mold), then follow the suggestions on the

Behind Floor Baseboards

The space between the wall and the baseboards serves as a great growing ground for mold. Since it is a fairly sealed off space, it traps moisture. Plus, a lot of dirt ends up here, providing the mold colonies with plenty of nutrients to thrive.

Basements / Crawl Spaces

If you suspect that you have a mold problem, then you should be especially conscientious of the basement or crawl space of your house. This level has more of a chance of fostering mold growth than any other level in the home.  In basements and crawl spaces, just look for any evidence of dampness. Be especially aware of any black mold growth that might be taking place in wooden building materials, especially in the framing, since this is the best path for mold to take to other parts of the home. It can also lead to the weakening of beams and other bearing walls that are crucial in the stability of the structure.

Water-Damaged Areas

Any area where flooding, leaks, or other types of water damage have occurred are prime candidates for toxic black mold growth.

Rooms / Areas with High Relative Humidity

If the relative humidity in a certain room or area is commonly above 55%, then over time, there is a strong likelihood a mold problem will occur. In which case, it is important to monitor areas with high humidity on a regular basis. In order to determine the relative humidity for a room or area, you will need a relative humidity sensor

Above Ceiling

Just as mold in the wall cavities can lead to mold growth in interior walls, the same can happen in the spaces above ceilings. Especially since a common source of water infiltration – roof leaks – start from above.  If you see any evidence of water damage or biological growth in your ceilings, then you should investigate right away.

Beneath Bathroom/Kitchen Sinks

This is yet another place where moisture is commonly a problem, and therefore another place where mold can often be found.

Behind Wallpaper

The glue from the wall paper attracts a lot of organic material (such as dust) that serves as a favorite nutrient of mold.

Moist Window Frames

The window frame is in a position where warm air commonly meets cold or cooler air, as a result of the temperature difference outside and inside. This formula leads to condensation, which leads to mold growth.  Look for biological growth in the seal where the window frame meets the wall.

Inside Wall Cavities  

This is another place where warm air meets cooler air, especially the walls around the perimeter of the home or building.  Plus, wall cavities are good at trapping moisture. In addition to all this, pipes often leak in between walls, where we are not aware they are occurring. If mold is present inside mold cavities, it will eventually manifest its presence by working its way to the outside of the walls, where it will be visible. If signs of excessive moisture and mold begin to show on your walls, you can smell the musty odor, and you or others in your home or building are showing health effects from mold, then it is likely growing in your wall cavities. If this is the case, then you will need to remove the drywall in places where you suspect the mold is growing within the wall. Then, you will need to clean and remove the mold.

Particle Board Material

This material is another desirable source of nutrition for mold.

Fiberglass Insulation and/or Backing and other Insulation Material

Mold does not live and grow on the insulation itself. However, fiberglass and other types of insulation collect a lot of dust and other organic particulate. It is this dirt and grime that are able to make insulation a nice home and breeding ground for mold.  Exposed insulation in the ductwork, attacks, and basements/crawl spaces are most susceptible to mold growth.


Just as moisture and dirt become trapped between walls and above ceilings, they also become trapped beneath the floor. Tile and carpet make great environments for mold since they collect a lot of dust and other organics for mold to feed on. Carpet can become especially ideal for mold growth since it also holds in moisture.

Ductwork/HVAC Systems

In addition to the insulation (if present), mold can grow in a variety of other places in the ductwork/HVAC system. Other than the insulation, the two other places mold is most likely to grow is the condenser or cooling coil and the drain pan. In central air systems, these are located in the air handler (by the fan).

The cooling coil cools the air that comes into the system below the dew point, to remove the condensation from the air. As a result, condensation builds up on the coil itself, making it vulnerable to biological growth, including mold.  The drain pan is located beneath the coil, and collects the condensation that drips off the coil. Naturally, the water in the drain pan can become the perfect environment for mold growth, especially if the pan is not sloped. If it is flat, then the water will become stagnant, increasing the likelihood of mold growth. If your system has an in-duct humidifier, then it can add too much moisture into the ductwork. When this added moisture combined with dirt and grime, mold can germinate in the ducts.  Evaporative Coolers (a.k.a. Swamp Coolers)

Evaporative coolers increase humidity in the home or building. They cool the air by evaporating water (which has a cooling effect), then blow this air inside. In which case, the air has an increased moisture content.

As a result, evaporative coolers increase the potential for mold growth, especially nearby the unit.


The drain pan beneath the refrigerator should be regularly checked for mold and other types of microbiological growth.

Plant Pots

The fact that plants need to be watered regularly, and that the soil contains valuable nutrients for mold, equals a haven for mold.

Cracked / Peeling Paint

This is a sign that there is excessive moisture within the wall, meaning that there could also be mold growth nearby.

Sweating Pipes

When this happens, track where the moisture is accumulating. This can lead you to mold growth.

Shower Curtains

Between the dirt and grime we wash off ourselves, and the water that can usually be found on shower curtains, mold is often to be found as well.