How to Find Concealed Mold

Sprinkler water damage

Do-It-Yourself Guide for How To Start: 

Very toxic mold can be completely concealed. You may not smell it. Some people exposed to toxic mold will feel fine. But the mold is still there and it may be compromising your health or the health of people you care about without event knowing it.

Do not completely trust any screening test including ERMI, HERTSMI or air testing results if symptoms or bloodwork is consistent with mold illness and those tests come back negative. I have had very good ERMI and air tests for me and for others in my family, and still found VERY toxic mold concealed. In one case the water damage was exposed and the ERMI still came back great. 

So what does one do if they have health issues that might be connected to mold or other environmental factors but there are no outward signs?

Here’s my list of how to start:

INSPECT the inside of your home or building

Use a flashlight to look for any changes in texture or color on surfaces. The signs may be very subtle. Early signs on that water might be behind drywall include sparkles on the surface, bubbling of paint, peeling of paint, emergence of a white powder substance. Any color changes at all should be noted. The flashlight is key to avoid the natural drop off of light from light fixtures. Be meticulous.

INSPECT the outside

Scrutinize during the day on a clear day, but also get outside when it is actually raining. Look for puddles or drainage paths near or towards the structure foundation or against the walls from the roof above. Note any grade slopes with are either level or sloping toward the structure. Neither are good. There should be a noticeable slope away from the structure on all sides. Six inches of slope in 10 feet is a good rule of thumb. Check all downspout connections and make sure you have extensions moving water well away from the structure. Make sure gutters are draining properly and not overflowing in locations and dumping lots of water on your walls or window openings.

INSPECT your systems

HVAC systems are the cause of possibly 50% of mold problems in buildings. Check coils and condensate drains. Check all vents to make sure they are unobstructed and drawing air well. This includes cooking vents, dryer vents, and bathroom vents. These vents should NEVER exhaust in the basement, crawl space, attic or from the underside of soffits If you don’t have working bathroom exhaust fans in rooms where showers produce moisture, there is likely to be a problem as the humidity alone over time will collect.

CHECK humidity levels in each room

Invest in a humidity monitor or even several. Humidity monitors cost between $9-$12 and are readily available through online stores, Walmart, and home improvement big box stores. There are also monitors that can show the comparison between indoor and outdoor humidity levels which are more expensive but can provide very worthwhile information. 

Cheryl Ciecko is an ALA, LEED AP, Licensed Architect who helps homeowners and building professionals create safe homes through online education to prevent mold, water damage, and poor indoor air quality. 


You can find her video masterclasses, online programs, and education subscription options at .


For detailed answers on your specific situation or building project, schedule your appointment for an individual consultation.




The information contained in this presentation is for educational purposes only and is not intended to diagnose, prescribe, treat, or cure any disease, ailment or injury to the body. It is not medical advice. FDA regulations prohibit the use of medical claims in conjunction with the sale of any product not approved by the FDA. Statements made herein have not been evaluated by the FDA. 

Any products, techniques, and/or personal usage tips referred to are not suggested as a replacement for proper treatment from a licensed health care professional. I am not a licensed health care professional and the decision to use or not to use any of this information is the sole responsibility of the listener and/or reader. Everyone is an individual with different body types, different blood types, different body chemistries, and it is important to remember that what works for one person may not work for another person.