Insulation wears out. Fiberglass sags and settles. Cellulose compresses. Rodents nest. The signs are usually obvious if you know what to look for.
Climbing Energy Bills
If your bills keep rising despite no usage changes, your insulation is failing.
Uneven Temperatures
One hot room or one cold room means localized insulation failure.
Visible Damage
Sagging batts, brown moisture stains, animal activity — all signal it's time to upgrade.