Do-It-Yourself Steps for Mold Investigation

Looking for water damage

How to evaluate your buildings for water damage

Discovering water damage and mold, especially concealed sources, can require detective work and close attention to details. Start with this list and compare your notes based on what you find to help focus additional investigation.

Here are the first 5 steps to take to evaluate your buildings for water damage and find mold:

History of water damage 

Flooding, pipe leaks, overflowing toilets and tubs, ice dam damage (icicles in winter), roof leaks, window leaks, condensation on surfaces, etc. are just a few possibilities. Note where and when these events happened. Check these locations closely, but also know that water can travel great distances before it settles to cause damage. Lack of a properly sized and functioning exhaust fan in bathrooms, will mostly likely lead to moisture accumulation with potential mold problems.

Downspout and rising damp on brick

Indoor & outdoor visual inspection

Look for surfaces and locations with discoloration (even slight), texture changes, even slight shine or powder accumulation. Any color changes should be photographed and monitored. Pay close attention to ceilings below rooms with plumbing.Check locations where any exhausts for bathrooms, kitchens or dry expel warm, moist air. Soffit venting of bathroom or other vents will cause mold in attics over time. Check attics, crawl spaces and basements also for improper venting in these locations.

Monitor humidity levels

Checking humidity readings is a good idea, as stored moisture in concealed spaces usually adds to the humidity levels in a room. Meters cost around $10 at Walmart, Amazon etc. Just give them time to acclimate and look for anomalies from room to room. In heating seasons below 40% humidity is normal. In humid summer months that number could be okay up to 55%. Higher readings or rooms with higher readings than other rooms is a red flag for further investigation. Check for a previous blog post on humidity monitors for more information on this topic.

Humidity and Temperature monitor

Inspect in the rain

Review the building and property during a rain event. Walk around the outside looking for gutter overflow, puddling along the foundation, indications of moisture saturation in walls, especially around openings, which may show as darkened areas which appear to soak up water. Many of these signs will go away shortly after the rain stops, so pay attention immediately. Brick and stucco are very good as showing signs of water accumulations immediately after rain events. Look for water pooling next to the foundation, gutters overflowing and not functioning properly, downspouts dumping on walls or foundations, window sills, door or windows, roofs draining into walls, etc.

Check the exterior of the building when it’s wet

Inspect and clean HVAC systems

Clogged condensate drains, dirty filters and coils, and even accumulation of debris in ducts can cause mold to flourish. Up to 50% of mold in building challenges are directly related to poorly maintained, poorly functioning and sometimes faulty installations of Heating, Cooling and Ventilation systems (HVAC). Check my prior blog posts for information on HVAC duct cleaning.

Dirty HVAC system

Important considerations

Know that very toxic mold can be completely concealed. You may not smell it. Some people exposed to toxic mold will feel fine others may get very sick.  Mold may be compromising your health or the health of people you care about without even knowing it.

Do not completely trust any screening test including ERMI, HERTSMI or air testing results if symptoms or bloodwork or history is consistent with mold illness. 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 some cases, the water damage was exposed and the ERMI still came back unremarkable – (score under 2.0).

Get a list of possible mold exposure symptoms. Also, check back to this blog for follow-up steps.

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.