Can Mold Grow Without a Visible Leak?

Why this question keeps coming up

People search the foundation for a crack because a crack feels like a real cause. Air feels too ordinary to be the villain.

What it looks like in York County

This is the entire July story in otherwise tight houses from Devers to North York. The wall sweats, the boxes get speckled, and nobody can find a drip. The gauge reads 67%. That is the leak.

What to do

• Log humidity for a week.
• Do the foil test on a wet wall.
• Dehumidify.
• Remove paper from the cold surfaces.

What makes it worse

• Excavate the foundation before you measure the air.
• Open windows every humid afternoon.
• Wait for a puddle as permission to act.

Foil test: condensation versus a leak.

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.