LB-07-008 -- Effect of Mastic on Duct Tightness in Energy-Efficient Manufactured Homes PDF

Over 60% of all manufactured homes built currently in the Northwest meet NEEM program standards and are among the most energy-efficient manufactured homes in the United States. Effective January 1, 2004, NEEM specifications require that all central forced air duct systems use UL181 AM or BM rated duct mastic for all sealing. Seventy-one homes built in the Northwest Energy Efficient Manufactured (NEEM) Homes Program after January 1, 2004, and sited in Oregon and Washington State were field tested to evaluate effectiveness of program specifications with respect to heating duct tightness and envelope tightness. Data collected in this study are compared to data from previous studies in the region for manufactured homes built in 1992–93, 1997–98, and 2001–02 when most systems were sealed with variously rated duct tapes. The duct leakage to exterior data collected in the field is also compared to total duct leakage data for the same homes as tested in the factory when available. A 43% reduction in duct leakage over the best previous value for the region was seen in the data for homes built to the new specification requiring mastic. The continuation of the trend in previous studies for overall improvement in envelope tightness was also seen.

Units: I-P