Many homeowners inquire about removing the old insulation from their attic, rarely is this necessary. The only time we recommend removing old insulation is when the insulation has been fire damaged, water damaged or heavily infested with rodents. Most homes have some old or “existing” attic insulation already in their attic. Typically we just add more insulation to what you already have in order to bring the attic up to an R-30 or R-38 rating. The existing insulation may be dusty, filled with old roofing debris and look quite tattered, but it’s just old material; it doesn’t contain asbestos nor contain anything that wouldn’t be rendered safe once new and fresh material is installed over it.
There’s no chemical interaction or problem with mixing various insulation materials either. We actually can save you money by using your existing insulation as a base and installing enough additional material over it to bring the attic up to R-30 or R-38.