For energy efficiency, your home should be properly insulated from the roof down to its foundation. This includes the following areas:
- Attic spaces
- Ducts in unconditioned spaces
- Cathedral ceilings
- Exterior walls
- Floors above unheated garages
Article source: The U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE). For the most up-to-date information please visit the EERE website.