2026-09-16 · Dave Kessler · 4 min read
Mold in East York Homes
The addition is the usual suspect: a crawl, a lower floor, or a porch that became a room.
Additions
We see this on radon jobs too — mixed foundations are on the East York radon page. For mold, open the crawl hatch under the addition before you buy a bigger air freshener. Crawl spaces explains the plastic.
Split levels
The lower level is a basement with better carpet. If it smells, treat it like a basement: gauge, no pad on a damp slab, and walls that are not hiding wet paper.
Remodel fans
Added baths in these wings sometimes exhaust into the joist bay. That is an attic or crawl shower. Find the duct termination outside.
Questions people also ask
+Can I encapsulate just the addition crawl?
+Is a split-level lower level livable?
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.