Gut-rehab projects must do one of the following:1. Meet the requirements in ASTME-2121 (See www.epa.gov/radon/pubs/mitstds.html), which includes: install passive radon-resistant infrastructure, including piping through slab that connects to exterior through sidewall or roof. In this case, the area under the slab must be tested for connectivity, to ensure the piping accommodates the entire sub-slab area. Depending on sub-slab connectivity, multiple source pipes may be needed. In this case, a post-construction test is still strongly recommended.2. Conduct radon testing (see EQ 09-15 for details). If the test shows minimal radon risks, no further action is required. If the test shows an unacceptable radon risk, an active radon mitigation system is required.
Updated 10/1/13 for rating system applicability.