Can I have new attic insulation installed over my old attic insulation?

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Answered by Tim Snyder, Guest Editor

Most attic insulation upgrades are done using loose-fill fiberglass or cellulose insulation that is installed with blowing equipment. In most cases, the new insulation can be blown in directly over existing insulation, as long as the old insulation is in good condition. It shouldn’t be wet, moldy or smelly. Some homeowners choose to have old fiberglass attic insulation removed because rodents have been living in the attic. As the old insulation is packed up and discarded, the attic space can be cleaned of animal waste and other debris as a prep step before the spray insulation is applied.

About the author: A journalist specializing in sustainability, energy efficiency and home improvement topics, Tim Snyder is a former executive editor of Fine Homebuilding and American Woodworker magazines. Tim's recent work includes a green remodeling manual for the Environmental Protection Agency, and a chapter on “Smart Shelter” for The Whole Green Catalog. Tim’s blogs and web content can be found at,,,,,, and other sites.