Indoor Mold FAQ

Questions such as ‘what is mold?‘ and ‘how do I detect mold?’ are important topics to consider if there is a mold problem in the home or if mold has been discovered. Other questions and concerns can arise as well.

1. How does mold get in my house?

Nature contains thousands of different types of molds

in forests, wetlands, lawns, gardens, and farms. These molds produce spores, which are microscopic “seeds” that are constantly blowing in the wind. Outdoor airborne mold spores are lowest during a “hard-freeze” winter and highest during a warm, damp summer climate. Conclusion: Natural outdoor mold spore counts vary from season to season and region to region. If you put a film outside during the testing period will it capture a sample of the natural background environmental spore count, for that hour, on that day.

When the wind blows

these natural environmental mold spores blow into and around buildings through windows, doors and drafty openings.

Buildings with open doors

and windows and window fans will have the highest level of “blow in” mold spores.

Buildings which are tightly built

with windows and doors kept closed and air conditioned will have the lowest level of “blow in” mold spores.

Normal “blow in”

mold spores which are not cleaned up by dusting, vacuuming or washing, remain inside as your “normal resident or background” mold spores.

“Background” mold spores

settle onto surfaces and mix in with the other house dust. “Background” mold spores will gradually build up on the most difficult to clean or infrequently cleaned surfaces, such as rugs, books on shelves, cloth furniture, drapes and blinds. These resident spores are dormant. They are not considered contamination.

2. Why does mold begin to grow indoors?

Mold contamination starts

to occur inside when the dormant “background” mold spores inside a building become wet through a leak, flood or condensation and begin to grow within the building. It is unacceptable to have mold growing in occupied buildings since it will destroy building materials and may cause chronic negative health effects which is why regular mold testing is important.

Visible Mold Contamination

Surface Mold is usually recognizable as blotches or a fuzzy or powdery-looking coating in black, gray-green or pink colors growing on a damp surface. It smears when touched and often stains the surface. After cleaning, it usually grows back. It is usually found on the walls where rain water has leaked in or on a wall with leaky plumbing or on walls and furniture which have been wetted by flooding or high humidity.

Hidden Mold Contamination

Hidden mold is growing in walls, under rugs, behind wallpaper, under linoleum, under floorboards, in the back of closets, on the back side of ceiling tiles, in damp basements, crawl spaces, and attics, etc. You can’t see it or often smell it. The spores get blown into the rooms by drafts through walls, ceilings, windows, floors, trim spaces or cracks, or walking on the rugs and floors, etc. Mold testing is critical for detecting hidden mold.

3. What is an acceptable amount of mold in indoor air?

“Normal” Indoor Mold Spore Levels

Scientists have not yet been able to set a simple standard or formula for how much indoor airborne mold is normal, due to the “blow-in” effect, because it varies based on every building’s fresh air exchange, cleaning practices, air filters, climate, season and locale.

Scientists and health officials agree that naturally occurring levels of environmental mold spores are not a threat to a normally healthy person. However, high levels any kinds of naturally occurring environmental mold spores may cause negative reactions in persons with allergies, asthma and other immune system disorders.

4. What is Abnormal? Is it abnormal to have any source of mold growing inside an occupied building?

Since all mold colonies eventually release spores into the air, they will eventually increase the mold spore count in nearby rooms or areas. Mold almost never grows alone as a single type. There are usually several different types of mold growing on a wet contaminated area.

When mold grows indoors, it is trapped and concentrates abnormally high mixtures of the spores, off-gases and chemical irritants which can only provide harm to your health, such as irritation to the eyes, nose, throat and lungs, stomach and in some rare cases, dangerous toxic effects – even to non allergic individuals. Mold testing will help you locate these indoor sources.

Once you find any source of growing mold, don’t worry about identifying their names – It’s an expensive waste of time unless you’re going to court! Just clean all of it up – safely (For instruction on how to do this use the MoldCheck™ Mold Testing Kits Clean Up Guide).

5. Taking Action – what do I do once I have found the mold?

Once you have found a source of mold growing within an occupied building, use the Mold Clean Up Guide to make a careful plan to clean it up.

6. How do I use my mold testing results?

Your mold testing results give you clues to track down sources of mold contamination growing indoors. Every building has some level of normal “resident” blown-in mold spores. The way to find out if an indoor source of mold contamination is increasing your spore count is: A) to locate the rooms with the highest spore counts, and; B) then conduct a detailed search for the possible hidden source in high spore count rooms, using The Building Detective Guide™.

Use these clues and your Building Detective Guide™ to search for sources of growing mold.

Search Clue #1: Take your Guide and go to the rooms with the highest spore counts.
Search Clue #2: Inspect the rooms or areas which have the highest mold spore counts.
Search Clue #3: Inspect all rooms or areas which have a mold spore count that is more than 20-30 colony counts.
Search Clue #4: Search areas or rooms which make anyone sneeze, itch, get a runny nose, itchy eyes or cough.
Search Clue #5: Search areas that smell musty or have an unexplained odd or stuffy odor.

Read the Important Facts about Indoor Mold (above). The MoldCheck™ Mold Test Kits should help you find the hidden source of mold if you have one inside your building.

If you have any questions, give us a call or drop us an e-mail at