Should I test for radon before finishing my basement?

Yes, even if the basement is unfinished. Pennsylvania DEP estimates that roughly 40% of homes in the state have radon above the EPA action level of 4.0 pCi/L. Test before design so any needed mitigation can be planned before new walls and ceilings go in, including pipe and fan routing around the new framing. The statewide estimate does not predict an individual home's result.