Is White Mold Dangerous?

Why this question keeps coming up

Someone online said black is the bad one, so white gets ignored until the joist is fuzzy.

What it looks like in York County

Fieldstone downtown throws efflorescence constantly. Joists over a Spring Garden crawl throw actual white mold when the soil is open. Different surfaces, different meaning, same need to find water.

What to do

• Crush-test powder on masonry — salts powder, mold smears or smears and smells.
• Meter the wood.
• Fix humidity or the leak.
• Clean or remove the organic material that is actually growing.

What makes it worse

• Paint salts the same day.
• Assume white means mildew and therefore harmless.
• Scrape dry mold into the air without protection.

Block and stone: a closer look.

Questions people also ask

These pages are homeowner education from Radon Mitigation of York, written by Dave Kessler. They are not a medical diagnosis, a species identification, or an insurance determination. Color does not tell you which mold you have. If someone in the house is sick, talk to a physician. EPA's homeowner guidance treats roughly 10 square feet as the line where many people stop DIY cleanup and call a remediation crew — sooner if sewage, HVAC, or anyone immunocompromised is involved. We are a radon and basement crew. When we are already under a York house we will tell you what we see and what we would do in our own place. We do not pretend a radon fan is a mold remedy.