Black mold harmless cosmetic mold from building materials when constructed?

I found what appears to be black mold isolated to the bottom of a couple of floor joist. In that same area/corner of the house there seemed to be a lot of efflorescence. The efflorescence was widespread. Would that be a coincidence or could it be something worth having a mold inspector take a look at? Didn’t find any water in the crawl space at all after heavy rain last night.





Both conditions require moisture, or high humidity, coupled with poor ventilation.

Now explain what “black mold” is supposed to mean…


he said he’s not a mold inspector, Dom.

Steve, if you’re not qualified to test/inspect mold, don’t try. Call it for inspection by a mold inspector.

Steve, Be careful with your wording. Black mold refers to a rare very dangerous species, not the color. Calling our black mold in an inspection report could get you in trouble. You can call it mold or bio-growth, but black mold sounds like you’ve identified the species, and you have not, because a lab didn’t look at it.

I’ve always referred to it as organic growth and recommended the client to get a mold inspection for health and safety reasons.