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Mold & Indoor Air Quality Library

Water Damage & Prevention

Moisture control: the key to mold control

Best practice Sources: EPA 402-K-01-001

In plain English

Nearly every mold problem starts as a water problem — a roof or plumbing leak, condensation, a clogged AC drain, or ground that slopes toward the house. Find and fix the source first; everything else depends on it.

Keep indoor humidity below 60%, and ideally between 30% and 50%. In Central Texas that mostly means an air conditioner that is sized and running correctly, bath and kitchen fans that vent outdoors, and a dehumidifier where the AC can't keep up.

Key points

  • Fix plumbing and roof leaks as soon as you find them.
  • Dry wet or damp spots within 48 hours.
  • Keep AC drip pans clean and draining.
  • Vent dryers and other moisture-making appliances outside.
  • Slope the ground away from the foundation.

Official text

EPA 402-K-01-001 — Prevention p. 3 Best practice

The key to mold control is moisture control. Solve moisture problems before they become mold problems!

Sidebar: Mold Prevention Tips

  • Fix leaky plumbing and leaks in the building envelope as soon as possible.
  • Watch for condensation and wet spots. Fix source(s) of moisture problem(s) as soon as possible.
  • Prevent moisture due to condensation by increasing surface temperature or reducing the moisture level in air (humidity). To increase surface temperature, insulate or increase air circulation. To reduce the moisture level in air, repair leaks, increase ventilation (if outside air is cold and dry), or dehumidify (if outdoor air is warm and humid).
  • Keep heating, ventilation, and air conditioning (HVAC) drip pans clean, flowing properly, and unobstructed.
  • Vent moisture-generating appliances, such as dryers, to the outside where possible.
  • Maintain low indoor humidity, below 60% relative humidity (RH), ideally 30 – 50%, if possible.
  • Perform regular building/HVAC inspections and maintenance as scheduled.
  • Clean and dry wet or damp spots within 48 hours.
  • Don’t let foundations stay wet. Provide drainage and slope the ground away from the foundation.

Citation: EPA 402-K-01-001, Prevention, p. 3.

Read on the official site ↗ See it in the full EPA 402-K-01-001

Citations