The State of California’s energy code, 2016 Title 24, requires high performance attics in new single-family residential buildings. Builders can follow one of two prescriptive paths or use the performance path to meet this requirement. According to the American Chemistry Council a proven alternative design for high performance attics is the application of spray polyurethane foam (SPF) insulation on the underside of the roof deck to create an unvented attic. The two most common Title 24 compliance simulation tools, EnergyPro and CBECC are currently not configured to easily model SPF unvented attics. To address this issue the American Chemical Council partnered with ConSol to develop the publication “Spray Polyurethane Foam and the California 2016 Title 24 Requirement for High Performance Attics”. This technical brief provides guidance on simulating unvented attics using the California code compliance simulation tools. According to the report, for a typical home in three different California Energy Commission climate zones, the modeling runs demonstrate that an unvented attic with R-28 SPF slightly outperforms the 2016 Title 24 prescriptive designs. Use of R-38 SPF to create an unvented attic significantly outperforms the prescriptive high performance attic designs when more reliable modeling is applied. To download the report go to Spray Polyurethane Foam and the California 2016 Title 24 Requirement for High Performance Attics For more information please contact Rick Duncan of SPFA at rickduncan@sprayfoam.org
