 staking method for poly sheeting may not be used in crawlspaces with no slab.
- ENERGY STAR exceptions for capillary break (polyethylene) under slabs do not apply. Poly is required in Radon Zone 1.
Advisory: 10 mil polyethylene is recommended if crawlspace floors are not covered with a concrete slab.
2.1 Radon-Resistant Construction
NOTE: Completion of the ENERGY STAR requirements now satisfies the following Indoor airPLUS requirement:
Air seal all sump covers (Builder-W 1.7).
Additional Indoor airPLUS Requirements:
- Construct homes in EPA Radon Zone 1 (see www.epa.gov/radon/zonemap.html) with radon-resistant features to conform to ASTM E1465; or IRC, Appendix F; or NFPA 5000, Chapter 49. Consult EPA's "Building Radon Out" (EPA 402-K-01-002) for general guidance on installing radon-resistant features.
Visually verify the following requirements:
- Capillary break installed according to Specification 1.2, irrespective of climate zone.
- A 3 or 4 in. diameter gas-tight vertical vent pipe, clearly labeled to conform with the radon-resistant standard used, e.g., “Radon Reduction System” or “Radon Pipe” or “Radon System.” The vent pipe shall be connected to an open T-fitting in the aggregate layer (or connected to geotextile drainage matting according to the manufacturer’s instructions) beneath the polyethylene sheeting, extending up through the conditioned spaces and terminating a minimum of 12 in. above the roof opening. For crawlspaces, install at least 5 ft. of horizontal perforated drain tile on either side of the T-fitting, attached to the vertical radon vent pipe beneath the sheeting and running parallel to the long dimension of the house.
- Radon fan installed in the attic (i.e., an active system) OR an electrical receptacle installed in an accessible attic location near the radon vent pipe (i.e., a passive system) to facilitate future fan installation if needed.
- Foundation air sealing with polyurethane caulk or the equivalent at all slab openings, penetrations and control or expansion joints.
Note: Consult local building codes to determine whether additional radon requirements apply. In January 2013 ANSI-AARST published a standard of practice for “Reducing Radon in New Construction of 1&2 Family Dwellings and Townhouses (CCAH-2013),” available at www.aarst.org/bookstore.shtml.
- Elevated levels of radon have been found in homes built in all three zones on EPA’s Map of Radon Zones. Consult your state radon program for current information about radon in your area. Go to www.epa.gov/radon/whereyoulive.html and click on your state for contact information.
- EPA recommends, but does not require, that all homes built with radon-resistant features in EPA Radon Zone 1 pre-emptively include a radon vent fan. EPA also recommends, but does not require, radon-resistant features for homes built in EPA Radon Zones 2 and 3. EPA further recommends that all homes built in EPA Radon Zones 2 and 3 with radon-resistant features be tested for radon prior to occupancy. A radon vent fan should be installed when the test result is 4 pCi/L (the EPA action level) or more.
- The U.S. Surgeon General and EPA recommend that all homes built in Radon Zones 1, 2 and 3 be tested for radon. Provide buyers with EPA’s Citizen’s Guide to Radon, encourage them to test for radon and refer them to www2.epa.gov/radon for more information.
- If soil or groundwater contamination is suspected on or near the building site (e.g., former industrial sites), volatile chemical contaminants from soil gas or vapor intrusion into a building may pose an IAQ risk. In such cases, EPA recommends radon-resistant features consistent with Specification 2.1, which can minimize or prevent the vapor intrusion into a house. See the EPA Vapor Intrusion Primer or ASTM E2600 for more information. You should also consult your state, tribal, or local environmental regulatory agency for information on the location of contaminated sites, including those subject to Superfund (CERCLA), Resource Conservation and Recovery Act (RCRA) cleanup requirements, or the Brownfields program. Visit