Adding insulation to an under-insulated attic can lower heating and cooling bills by about 15 percent, making it one of the best home upgrades for the money.
Check your current depth first, since many homes sit well below the recommended level for their climate.
Seal air leaks around pipes, vents, and the attic hatch before adding insulation, because insulation alone cannot stop drafts.
Rent a blower and install the material yourself, or hire a pro, since the work pays back within a few years either way.