Photograph: mold hidden behind basement wall paneling How to Recognize Harmless "Cosmetic" Mold in buildings
Don't spend a fortune on needless cleaning of cosmetic-only mold growth

  • COSMETIC MOLD, RECOGNIZE - CONTENTS: How to identify cosmetic & other low-risk or harmless black and other colored mold in buildings. Age of mold: how to determine that mold has not been actively growing on building framing. How to tell, with confidence that black mold you see on building framing or other wood surfaces is old, came in with the lumber from the lumber yard, and is a cosmetic stain fungus.
  • POST a QUESTION or READ FAQs about how to spot harmless or cosmetic black mold in buildings

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Cosmetic mold generally does not need to be tested nor removed. How can we recognize harmless mold indoors?

This article discusses how to recognize mold that may be harmless, or cosmetic only in importance in buildings. We look for mold in buildings not only where mold is visible but also by context: where do we see leak stains, or where do we see building practices most likely to have produced a hidden leak or moisture problem?

Ice dam leaks in walls, hidden plumbing leaks, roof spillage by the foundation, are all common clues that often track to a wet building wall or ceiling cavity and from there to a hidden mold problem which may need to be addressed.

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How to Recognize Harmless Cosmetic Molds and Other Low-Risk Molds

Photograph: typical cosmetic bluestain mold on new framing lumber, floor joists -  © Daniel Friedman

Cosmetic-only Ceratocystis/Ophistoma bluestain mold is shown on the floor joists in the new construction framing in the photo just above.

This is a harmless, cosmetic-only mold that does not damage the lumber and is not a pathogen for humans. Here's a good example of the observation that not all "black mold" is "toxic black mold". It will be totally hidden when the ceiling drywall is installed.

The mold shown in the photograph above is plain to see during construction, but will be covered and hidden completely when the contractor installs the ceiling drywall.

One of our clients discovered this scary-looking black mold during a renovation and was quite concerned that a major toxic black mold reservoir had been found in the building.

He client was facing a very costly mold cleanup project if this mold had to be addressed as a toxic material. Luckily this was not the case in this instance, as was easily demonstrated both by a simple inexpensive lab test and confirmed by onsite inspection of other framing details discussed at "Cosmetic Molds" linked-below.

So sometimes the mold in your house might be only a cosmetic concern.

"Bluestain" or Ceratocystis/Ophistoma is common on framing lumber and we often find it in attics on the under side of roof sheathing. Unless it's in finished portions of living space where it creates a cosmetic problem, no particular action needed to address this black mold.

Detailed advice about spotting harmless black mold including how to determine by visual inspection alone whether or not you're probably looking at one of these common framing lumber cosmetic molds is

Warning notice about Cleaning Up Mold Yourself

Guidelines defining what's a "large amount" of mold and what's reasonable for a homeowner to handle have been published by several states including New York and California. Links to some key documents describing mold cleanup and mold remediation procedures are

People who are allergic, asthmatic, infant, elderly, immune-impaired, etc., should not disturb mold and should not be in the area where mold remediation is being performed. Consult with your doctor, health department or other professional before tackling this job yourself.

On occasion some visible mold can be determined to be harmless and "cosmetic" old mold that was present when the building was constructed.

While it is always possible that additional more harmful molds are present in addition to the cosmetic mold, if there is no leak history nor any other evidence of mold growth in a building and if there are no health or building-related occupant complaints, the identification of the cosmetic mold described here might be accomplished by visual inspection alone, saving on more costly professional mold tests.


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