Radon mitigation plan

A homeowner in the Appalachian region of Virginia posted a detailed question online about finishing a do-it-yourself radon mitigation project on a 1940s house with a dug-out basement and crawl space. Radon is a naturally occurring gas that can build up in basements and crawl spaces; high levels are a health concern, which is why homes get fitted with mitigation systems. This homeowner already runs a dehumidifier in the basement and has installed a radon fan drawing suction from the sump and from two points in the basement, plus one in the crawl space. The crawl space floor is already covered with thick plastic sheeting.

The remaining questions are about the basement, which has a concrete floor poured directly over clay with no gravel layer underneath. The homeowner wants to seal plastic sheeting to the basement floor and walls so they no longer need to ventilate the basement in cold weather just to keep radon levels down, since that ventilation raises heating costs. Open questions include how to attach the plastic to brick walls, how high up the wall it should run, whether a drainage layer or perforated pipe is needed under the plastic to help the fan pull radon out evenly, and whether foam insulation should go above or below the plastic.

This is a specific do-it-yourself project rather than a product, program, or rebate announcement, so there is no broader news here for other homeowners. Anyone dealing with radon in an older home with a dirt or unvented basement may recognize similar tradeoffs between sealing, ventilation, and heating costs.