Living with Mold Risks

How To Live With A Basement or Subgrade Living Space


Main Problems:

Moisture intrusion and organic materials that grow mold.

Air contamination that spreads mold throughout the residence.

Severity of Mold Risk:

Cost of Recommendation:



The Problems

Basements Are More Susceptible to Mold Problems Due to Moisture Intrusions

All living spaces built below ground level are very susceptible to moisture intrusion. And as we know, moisture (water) is necessary for mold to grow. This moisture intrusion may come from:

  • Hard rains or flooding brought in by gravity
  • A high water table bringing water through the flooring or walls
  • Excessive humidity from moist ground against the subgrade walls and flooring without a moisture/vapor barrier or with a compromised moisture/vapor barrier
  • Leaks from plumbing or spills on the ground floor or upper levels
  • A failed sump pump, which creates standing water

Other factors also contribute to making mold growth more likely. There is often very little ventilation in basements and subgrade spaces to push contaminated air out and bring clean air in. The organic building materials of these spaces make things worse since they are prone to issues from the moisture intrusion. All these factors contribute to mold, yeast, and bacteria growth. 

Mold-Contaminated Air Travels Up Through Your Residence

If the basement or subgrade area does get a mold problem, that contaminated air will be carried up through the residence by what is known as the “stack effect”. The stack effect is defined as the movement of air into and out of buildings through unsealed openings, chimneys, flue-gas stacks, or other containers, resulting from air buoyancy. Buoyancy occurs due to a difference in indoor-to-outdoor air density resulting from temperature and moisture differences. The result is either a positive or negative buoyancy force. The greater the thermal difference and the height of the structure, the greater the buoyancy force, and thus the stack effect. The stack effect helps drive natural ventilation and air infiltration. Bottomline — construction science tells us that mold in your basement will travel up into the rest of your residence.

Mold Prevention & Recommendations

How To Live With A Basement or Subgrade Living Space


Monitor Humidity & Moisture



Humidity – Buy a hygrometer and monitor the humidity to assure that it does not exceed 60%. Amplified humidity could indicate amplified mold growth.

Our Recommended Hygrometer

Water Pooling – Ensure that there is no standing water on the floor. If there is ever standing water, dry it as soon as possible (ideally within 48 hours of it being present) and ensure that the humidity is <60%.

Moisture Detection – Use one or more moisture detectors to alert you if water is present.

Our Recommended Moisture Detector.

Nice to have

Heavy Rain – Within 48 hours of a significant rain (greater than ~0.5” in an hour) perform an infra-red (IR) camera inspection on all indoor walls and ceilings. This can be done by hiring a home inspector or indoor air quality inspector to perform the IR investigation, or by buying an IR camera and DIY. We recommend doing this every ~6 months.

Our Recommended Infra-Red Camera


Improve Your Basement/Subgrade Living Areas



Ventilation – Improve the ventilation in the subgrade areas. This can be done with an Energy Recovery Ventilation (ERV) System.

If Possible

Remove Organic Building Materials – If possible, do not use organic building materials in these subgrade areas (e.g. – drywall, wood framing, wood flooring, etc.)


Maintain the Area



Clean – Consider a maintenance strategy using natural cleaning products that fight mold, such as: the HavenMist Kit by BioBalance or the Remedy Air Maintenance Candle by CitriSafe.

HavenMist Kit by BioBalance

Remedy Air Maintenance Candle by CitriSafe

Maintain Sump Pump – Monitor the sump pump to ensure that it works properly. Keep it clean.


Periodically Test for Mold



Every 6-12 months check your indoor air for mold growth with the Mold Check-Up. If your results show significant mold growth, that could be an indication of mold in your basement.

Guides for tackling mold

Living With Mold Risks

Guides for reducing mold and maintaining cleaner
environments in situations we can’t change.

Flat Roof



Visible Mold


Indoor Plants


Evaporative Cooler