The basic elements for RRNC are the same in multi-family buildings - see EQ 09-16 for details. Multi-family projects should follow the ASTM-E Standard 2121 for details about how to design the sub-slab soil-gas collection system. See http://www.epa.gov/radon/pubs/mitstds.html for information on how to get a free copy of the Standard.
Updated 10/1/13 for rating system applicability.