Minnesota Radon Rules If you had to answer complaints from homeowners and realtors every day about improperly installed systems by non-regulated/non-certified contractors, you would understand. There is nothing more frustrating than talking with a 90-year-old widow who had a bad system installed, can't sell her house and doesn't have the money to "do it over". I'm not going to get in a debate over this, this will be my last comment. Chrys