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Mold Testing – The Basic

What Is Mold Testing?

Mold testing and inspections have become a very large industry. The health effects of mold are severe and hence we need to identify possible risks of exposure. The information below is a general overview. First, we will address where to look for mold and mildew in various types of buildings, then we will discuss the equipment used and then we will wrap up the discussion with a brief look at sampling.

Where Do I Start?

The first rule of thumb when looking for mold is to think – wet, damp, and humid. Mold grows where there is a moisture source.

pin leak

For example, a pinhole leak in a pipe can lead to mold in the walls, carpet, flooring and any other area the water can flow. It is very important to note that if you find a leak and are able to completely dry the area within 1-2 days then it is likely mold will not begin to grow. So if you spill a bucket of water on the carpet and dry the carpet as well as the backing and pad completely within 24 hours – you should be safe from mold growth.

Test The Flooring

Always do your mold testing in carpet areas. Especially where these areas enter into a humid environment. For example basements, laundry areas, carpeted bathrooms, and the carpet that adjoins these areas. It is very common for mold to occur because water contaminated the area and it was never properly dried out. Under the carpet there is a padding. This padding holds water very well and is very difficult to dry. Oftentimes the pad is not completely dry after a spill cleanup. The carpet is then layed down on top of the moist pad and in 48 hours – mold begins to grow.

Smell – the essential mold test?

Testing these areas is always advisable. Especially if there is any moldy or “stale” smell in the area. One last note – it is not uncommon to remove and replace the pad under carpet after a spill – this way you have a better chance that the moisture is completely removed from the area.

brown mold

When looking for mold remember that not all mold is black. Mold comes in a variety of colors and does not need light to grow. Look along the inside of wallpaper, backside of paneling, as well as on top of ceiling panels. These are all areas to test for mold. It is very common for dampness to occur on the inside of crawl spaces and around utility ducts and plumbing. This pipes oftentimes have condensation which of course is moisture and can cause the growth of mold. Always test for mold anywhere you find moisture. One place commonly overlooked when looking for mold is on the inside of utility chases and the inside of air ducts. The air inside the ducts can contain moisture that aggregates in joints on the tubing and mold can begin to grow.

Commercial Buildings Mold Testing?

Inside commercial buildings it is best to talk to the maintenance and service personal about past leaks or tenant complaints of foul smells or water. There is nothing better than walking the property with the responsible maintenance personnel who normally are more than helpful in identifying potential and past problems. Be certain to ask them about the way past problems were handled to ensure there is not mold resulting from a previous problem that was not properly handled. These are all crucial parts of thoroughly doing mold testing.When touring the commercial building look into air ducts as well as crawlspaces. If you note a white sandy material on the duct or just in the crawl space – this indicates there may have been a past problem with moisture. Also, always smell as you move through a building. Mold have a distinct musty smell – if you smell it – there likely is a problem.Of course in a commercial building the entire heating and cooling system areas need to be examined. These areas are notorious for having moisture and oftentimes are the starting points for mold contamination. Mold contamination anywhere in the duct system of a building could pass mold spores throughout the entire building and potentially cause mold symptoms for occupants throughout the facility.A key step when looking for mold in a building is to determine whether there has been a water leak. Maintenance personnel are frequently among the first to know when moisture problems have occurred. In some cases, management or health and safety personnel will have been notified. Either way, I will say it again – always ask the maintenance personell.

Do I need A Professional?

Mold testing can be done by the lay person but in actuality it is best left to a professional. A professional has the proper equipment and experience to identify mold. The professional also knows when they encounter a dangerous mold situation and are rained to not spread the mold throughout the building. For example, an amateur can easily and accidentally spread mold throughout a home by disturbing a spot of mold within an air duct. The professional would know to shut off the air duct and clean the mold and stop further contamination.


Professionals also use specialized equipment. They use borescopes, moisture meters, and specialized techniques to identify mold areas. The average mold professional also has the proper protective gear to ensure they are not over exposed to any dangerous situations. They are also qualified to determine what is a minor contamination and what is a major problem that can be harmful to building occupants.Investigating hidden mold requires caution since disturbing moldy areas may spread mold throughout the building. Opening and closing air handlers, for example, can send high levels of dust and mold into the air. Personal protective equipment (PPE) is not always needed when looking for mold, but it should always be available. If mold might be released into the air, investigators should use PPE to reduce exposure.

Tools For Mold Testing


Testing does not require too much by way of specialized equipment. Certainly when a problem is found it takes a lab to identify the specific strain of the problem as well as potential mold symptoms. But the best equipment when looking for mold is, believe it or not, your nose and your eyes. Maybe a light source to see dark areas. Remember the borescope mentioned earlier? It is simply a tool to all you to see with your eyes areas you cannot see without it.The borescope can be run down an air duct, in tight spaces or even into walls along piping. It is simply a “scope” that goes into a “bore” or hole in order to allow you to see what you cannot see without it. It is particularly useful for seeing the backside of drywall in bathrooms, kitchens, and laundry areas.The other primary tool used for mold testing is also a moisture meter. A moisture meter or humidity gauge simply allows the investigator to determine where there is high moisture. Remember any place with prolonged exposure to moisture can easily grow mold. It is amazing how the insulation above your ceiling or drywall in you home or even wood in the bathroom vanity can hold enough moisture from steamy showers to allow for mold growth. Remember mold only needs 24-48 hours of moisture – take a couple long showers over a couple days in the winter and it is not likely the wood in your floors in your bathroom will ever completely dry out. And it is just that easy that you can begin a mold problem.

Is An Expert Worth The Money?

After all this discussion you may conclude you are not interested in the services of a professional. Remember a professional is trained to help you – they will find what you cannot and they will be able to determine a real problem versus a problem that can be handled easily.Once mold is found then you do not need to provide some samples for review. The professional is worth every penny in this instance because they will be able to asses the type of mold as well as the extent of the problem. Oftentimes there is a lot of mold that is unseen whenever you find a problem. The professional is equipped to evaluate this. If there is a potential for a lawsuit or insurance claim the professional will need to take samples.Otherwise the main concern is cleaning up the problem. This clean up is given the fancy word of mold remediation. The goal of mold remediation is to locate the moisture source, stop it, dry the area completely, and kill and remove the existing contamination. That is all there is to it. Simple process but a professional is advisable to ensure your health.The professional can then take sampling of the air in the building to ensure that the mold has properly been removed and that it is save for everyone. Mold sampling is a subjective process so be certain to employ a license mold remediation expert and check there references. It is perfectly acceptable to get more than one opinion and quote when encountering a mold remediation contractor quote.

Jumping To Conclusions

One last thing to think about looking for and conducting mold testing. Not everything that appears to be mold is actually mold. Carpet stains, black on pipes or walls – it could be dirt, it could be insect residue, it could be contractor leftovers from original construction or it actually could be mold. There are home test kits that you can purchase but the results of these are far from perfect. While it is important to take your mold testing seriously also remember to keep your calm. Just because you see mold does not necessarily mean it is harming you in a sever way. When you see the mold – consult a professional and let them help you understand the ramifications if any.


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