Once your attic is brought up to the current standards, you should not need to insulate your attic again unless one of the following events occurs: - Another contractor does work in your attic and disturbs the insulation (e.g., installs a bath fan, etc.) - Raccoons, squirrels, or other critters get in and cause damage - Wind and/or water damage (e.g., storm with high winds or a tornado can possibly move insulation)