How much insulation do you need in your ceiling to get effective insulation protection?

The minimum requirement for ceiling insulation is R-30, but the recommendation is R-38-49. Proper insulation can cut energy costs by as much as half! Also, consider insulating outside walls, attics, spaces between floors, around heating ducts and pipes that are exposed to the elements. Insulate nooks and crannies such as wall outlets, gaps in siding and around the foundation, and holes around pipes, ducts, and exhaust fans.