I've just finished a radon mitigation project on a home I am selling. The greater Atlanta area has higher than normal radon levels, probably due to the large amounts of subsurface rock. This is the first time I've had to do this on a house, so thought I'd share the details. It began when buyer during due diligence tested for radon (first time that has happened). Test results came in suspiciously high (and fast), so I hired a professional radon testing company. Their results were not nearly as high but still above the recommended minimum levels. Honestly, I'm not totally sold on the ethics of the whole radon industry. But now that this has been confirmed I have to disclose.
I hired a local radon mitigation company to install a passive exhaust system. The house has an unfinished basement. The passive system is designed to suck any radon gases from the ground below and vent them outside the house (photos below). They dug two holes below the slab, and put one hole in the foundation wall; then installed pvc pipe up to the ceiling and out the back, where it turned upward, connected to a fan and then vented out above the roof. They also sealed up any cracks in the slab and foundation wall to keep the gas out. One day installation, and all the work was done neatly and cleaned up. There is a monitor inside the basement to confirm that the fan is running. They provide a 10-year warranty that the radon levels will be below the recommended minimum, which I can transfer to the buyer. The testing company came back out and set up their machine today for a post-mitigation test. Tests have to be a minimum of 48 hours.
It turned out to be not as painful as I thought. Total cost of the system was about $2,000; pre and post testing was a total of $300. Certainly not money I wanted to spend, but when I heard "radon" I was thinking it was going to be a five figure problem.
If anybody runs into this I'd be glad to recommend both the testing company and the mitigation company. I think it's important that they be separate companies....too much conflict of interest if the testing company also does the mitigation work.