R Radon Mitigation Of York

2026-07-28 · Dave Kessler · 4 min read

Summer Humidity and Basement Mold in Pennsylvania

The wall is not suddenly cracked. The air got wetter than the wall is cold.

Dehumidifier running in an older stone basement
  1. The July pattern
  2. Airing out, translated
  3. What to set and forget

The July pattern

We walk into basements the week after a humid stretch and the block looks like it rained indoors. Toilet tanks sweat. The homeowner is sure the footer failed. Sometimes it did. Often it is condensation. A gauge that says 68% is the whole diagnosis.

Airing out, translated

Air out when the outdoor air is actually drier — a cool, dry day, or winter afternoons when you are not freezing pipes. Do not air out because the upstairs feels stuffy. Stuffiness upstairs and a wet cellar are different weather.

What to set and forget

Dehumidifier on a hose, target under 50%, cardboard off the floor, and a glance at the gauge every Sunday in July and August. Sizing help is here.

Questions people also ask

+Does air conditioning dry the basement?
If the basement is on the same system and the unit actually runs, it helps some. Many York cellars are outside that duct loop. They need their own machine.
+Is mold worse some summers?
Yes. A wet June plus a closed house is a different year from a dry one. The foundation did not change. The dew point did.

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.

Keep reading

Humidity Targets for Pennsylvania Basements

Keep a York basement under 60% relative humidity, ideally 30–50%. How to measure it, and how to tell if a dehumidifier is keeping up.

Basement Condensation Versus a Real Leak

Sweating block walls in a York July are often condensation, not a cracked foundation. How to tell the difference before you excavate.

What Humidity Level Prevents Mold?

Keep York basements under 60% relative humidity, ideally 30–50%. How to measure it for more than an afternoon.

Musty basement? Start with the water.

Call Radon Mitigation of York if you want a local walkthrough of a damp cellar, crawl space, or a house where radon work and moisture are tangled together. Mon–Fri 8am–6pm, Sat 9am–2pm.

877-552-8556 Request a visit

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Mold guides live at /guides and the questions people ask are collected on the FAQ.

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