Solvent-based HVAC Duct Sealant
This information reflects our best understanding of product composition in 2020.
In forced air heating and cooling systems, conditioned air is distributed using a duct system. Air leaks can occur at joints within the HVAC duct system. To prevent leakage, ducting can be sealed using a tape or a wet-applied sealant. This CP...
In forced air heating and cooling systems, conditioned air is distributed using a duct system. Air leaks can occur at joints within the HVAC duct system. To prevent leakage, ducting can be sealed using a tape or a wet-applied sealant. This CP describes a solvent-based duct sealant for sealing joints of low, medium, or high velocity HVAC ducts against leakage. Solvent-based duct sealants are commonly advertised for use on metal ducts, but some can also be used with fiberglass duct boards. These products are applied with a caulk gun or brush and can be installed with or without reinforcing tape. Those products that are advertised for outdoor use also likely contain a UV stabilizer, but that was considered outside the scope of this CP. Some products may additionally contain a hazardous flame retardant or antifreeze, but these were not found to be common. Minimum temperatures for application vary, but some allow for application down to 0F, allowing the product to be applied on unconditioned jobsites. Most solvent-based HVAC duct sealant formulations still have a high VOC content, with levels up to 408 g/L reported. Some low and "zero" VOC formulations are available. These typically use EPA exempt solvents such as acetone, methyl acetate, and tert butyl acetate. Note that tert butyl acetate is not exempt per South Coast Air Quality Management District (SCAQMD) Rule 1168, so low or "zero" VOC products using this solvent may not meet the District's limits on VOC content.