When Removal's the Only Option
Here's the thing: most insulation problems can't be fixed by adding more insulation on top. If rats have been living in your attic, that old fiberglass is contaminated. If you had a roof leak, that insulation's been wet. You can't insulate over that - you're just trapping the problem underneath.
We see this constantly in older Glendale homes. Homeowners call us for blown-in insulation, we get up in the attic, and discover a disaster. Mouse droppings everywhere. Mold growth. Insulation compressed down to nothing. That's when we have the conversation: this needs to come out first.