A: You do not want to spray over existing insulation, encapsulating it, which can lead to moldy batt/blown in. The old, settled blown-in or batt stuff is doing NOTHING for your home’s energy efficiency, comfort, and air quality and may even be contributing to allergies and mold.   Pull up the old insulation first, put down 1 layer of closed cell [...]

Read the rest of Q: Can I just spray foam over my existing blown-in insulation in my attic? It has been there for 15 years and has settled.