Yes, it is possible to add insulation to an existing garage door. Insulation kits are available that allow you to retrofit your door with insulation materials. However, for the best results and maximum energy efficiency, consider investing in a new insulated garage door. Investing in an insulated garage door offers long-term benefits, including energy efficiency, enhanced comfort, noise reduction, and increased home value. When considering a garage door upgrade, consult with a professional to determine the best insulation options and enjoy the advantages that come with an insulated garage door.