D07 · Mixed-foundation and multiple-zone radon system

ALT TEXT
Labeled mixed-foundation diagram showing basement, crawlspace, and slab collection zones connected conceptually to an active radon vent.

LONG DESCRIPTION
A wide house cross-section contains a basement, crawlspace, and slab-on-grade zone. Conceptual collection branches from each foundation zone join a vent riser and fan. The drawing communicates that mixed foundations may require combined methods; it does not claim that one fan, one riser, or the shown number of suction points will be adequate in a real building.

Source basis: U.S. EPA Consumer’s Guide to Radon Reduction (2025), guidance that mixed foundations may require combined techniques.
