Realized after testing our Radon levels were, at times, up to 15-20 pCi/L during wet or windy conditions. House is located in the foothills with huge boulders in the basement, a small slab area, and the rest dirt crawl space. Merritt measured the radon levels and tested the boulders, which are known for emitting high levels of radon. He returned with a detailed description of what needed to be done to correct the issue and the materials he would use. We did our due diligence and received a 2nd opinion/quote through another company, A rep was sent out and someone else at the office who didn't understand the complexity of the basement gave us a quote. They insisted on trenching and depressurizing the small slab first. If that didn't work they would cover the dirt and then the bouders with a 2nd fan installed. We chose Merritt, our concrete floor is intake. The boulders and crawl space are covered in a 20 mil white plastic, buttoned down and sealed neatly around all exposed areas with one fan in place. Our readings at worse case conditions are less than 1%. Highley recommend Merrit and True Air Technologies. 866-386-2912 read more