Get matched with top doorbell installation pros in Byram, MS

Rockwool insulation can last up to 100 years, but just how long this insulation lasts in your home depends on how well it's maintained. Poorly installed insulation may last only 30 years, so be sure to regularly inspect your home's insulation for water damage, settling, and pests to give your insulation the best chance of having a long lifespan.

The lifespan of crawl space insulation depends on how well you maintain your insulation and the type of insulation. Fiberglass will need replacing every 15 to 20 years on average if you don't have a vapor barrier in place. If you do have vapor barriers in place, then your insulation could last much longer. Spray foam insulation can last anywhere from 80 to 100 years. 

You do not always need to remove old insulation before adding new. If the existing insulation is in good condition—not wet, physically damaged, moldy, or infested with pests—you can add new insulation directly on top of it for a compounding effect. You can also mix different types, such as adding blown-in insulation around existing fiberglass batts.

However, removal is recommended if the old insulation is compromised by water damage or pests. You should also remove it if you plan to install a different type of insulation, like switching from roll or batt insulation to spray foam. If the existing insulation is very old or damaged, you will likely get more benefit from removing it and starting fresh.

Vapor barriers in attics are a bit outdated and most areas no longer recommend them for attic spaces. For vented attics, the best method is usually to install drywall and cover it with latex paint before attaching insulation fiberglass, cellulose, or foam insulation. When renovating an attic to use as a living space, a contractor can guide you on the best way to cover insulation.