This largely depends on the type of insulation you choose and the quality of the insulation. When you choose Gonz Insulation — an experienced and reputable provider in the Saint Louis area — then you can trust that your insulation should last at least 20 years. Of course, each material has a different lifespan. While fiberglass and cellulose should last between 20 and 30 years, you can expect spray foam insulation to last for more than 50 years (and closer to a lifetime in many cases).