We have recurring mildew/mold in certain areas of our home. It is a brick/wood ranch with a full basement under 1000 square feet.

Asked by Carol
Birmingham, MI

I have cleaned it all with bleach solution more than once, but it always comes back. I purchased a hygrometer, but it did not indicate excessive humidity in the house.


Michael Holcomb

Answered by Michael Holcomb

Byron Center, MI

Alliance for Environmental Sustainability (Headquarters)

November 12, 2012

This is one of those questions that raises more questions than answers.

If it is actually mold we need to look at what causes mold growth. Mold requires: a food source, oxygen, moisture and temperatures above 40-degrees Fahrenheit. 

You'll need to identify the moisture source

  • If the mold growth is on a surface that is common to an outside wall (or ceiling) the affected areas could be reaching dewpoint (the temperature necessary to condense moisture in warmer air).
  • Alternatively, you might have a moisture intrusion issue (from outdoors to indoors).
  • If it is a condensation issue you should be able to hire an insulation contractor to make repairs.

Elevated moisture levels in the home may be cyclical (short time frames after showers, cooking, watering plants, etc.). Increased use of bath fans may also help.

There is a condition called ghosting that mimics mold but is actually soot/dust/carbon build up on colder surfaces (but not so cold as to cause condensation). This condition is also the result of missing/defective insulation coupled with high particulate material in the air.



For more information:

Go to my website at for further information or for my contact information if you have any additional questions about this problem.

Also, read "Will a high-heat pest extermination process also eliminate mold systemically from my home?" a Q&A answered by David Willson.

Tagged In: mold removal, mold

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