The 2012 International Energy Conservation Code® (IECC 2012) includes new requirements intended to limit air leakage through buildings' thermal envelopes, including roof assemblies. These requirements are changes from the code's previous editions and could make designing mechanically attached single-ply membrane roof assemblies more complicated.
IECC 2012 Section C402.4—Air Leakage (Mandatory) requires buildings' thermal envelopes for all commercial (nonresidential) buildings, except those in Climate Zones 1 through 3, to include a continuous air barrier. Areas where a continuous air barrier is not required include Alabama, Florida, Hawaii, Louisiana, Mississippi, South Carolina and portions of Arizona, Arkansas, California, Georgia, Nevada, New Mexico, North Carolina, Oklahoma, Tennessee, Texas and Utah.
IECC 2012 provides three compliance options for air barrier selection and evaluation: materials, assemblies or whole building testing.