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Basement Mold Issues Identified & Solved

Depending on where you live, basement flooding can be a common source of mold and indoor air quality problems.

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What causes basement flooding?

The source of water in a flooding situation can range from extremely obvious (exterior flooding) to obscure (cold joint).  Compounding the difficulty is the erratic nature of many leaks.  A house can sit bone dry for 20 years, and without any warning, allow hundreds of gallons of water to enter.  The most common points of entry are:

  • Cold joint.  This feature occurs when the slab floor and foundation wall are poured at different times, creating a small crack that can allow moisture to enter.
  • Foundation cracks.  Cracks in the vertical foundation walls can allow large quantities of water to enter a basement.
  • Cracks in the slab.  Pressure from the groundwater can force water up through the concrete and into the basement.

Basement Flooding lead to Mold Growth on Sheetrock

When does basement flooding lead to a mold problem?

Thankfully, not all basement flooding events cause mold growth. The primary deciding factor in whether mold growth will occur relates to the duration of saturation.  If the basement is dried out within 72 hours, mold growth is unlikely. Unfortunately, in practice this can be difficult to achieve.  Often when your house is flooded, there are hundreds of other flooded homes in the area, making a fast response from a dry out company difficult.

How can I prevent basement flooding from causing a mold problem?

  • Contact a water damage restoration company or mold remediation contractor immediately.
  • Dry out all materials within 72 hours.
  • Utilize both heat and dehumidification in the dry out process.
  • Immediately remove the carpet pad.
  • Test all remaining materials with a moisture meter (sheetrock, trim, underlying framing, etc.)

Groundwater sources of indoor flooding

Flooded ground

Clogged French Drain

Mold caused by ground saturation

Mold caused by ground saturation


Improper drainage can lead to damaging siding and mold inside a home

Improper drainage can lead to damaging siding and mold inside a home

Ground flooding


Project Report > Inspection for Mold in Basement due to Flooding

General Information

  • The basement of the home had recently been flooded by ground water intrusion.
  • The home owner had immediately extracted all flood water, removed carpet and padding, and disassembled all cabinetry.

Laundry Room:

  • Moderate mold growth was noted on sheetrock behind laundry fixtures.
  • RH: 41.2%     Temp: 69.8F     CO2 = 492ppm     CO = 0ppm

Main Basement Area:

  • Large amount of contents remained in place at the time of inspection.
  • Remaining parquet flooring tests with increased moisture content and has become heavily warped and deformed.
  • Sink and cabinetry is set on top of affected parquet flooring.
  • RH: 38.9%     Temp: 71.7F     CO2 = 664ppm     CO = 0ppm

Basement Bedroom:

  • Water reportedly affected only a small portion of this area.
  • All carpet and pad had been removed by the home owner prior to inspection.

Basement Bathroom:

  • Water reportedly had no contact with this area.

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