[Fiberglass & Cellulose Insulation Contractor in Port Huron & Fort Gratiot MI | Insulation Plus, LLC Insulation Plus, LLC, is a MI insulation company specializing in the installation, replacement and maintenance of insulation located in Port Huron, Michigan. Insulation Plus, LLC employs only the best technicians for insulation to help you save on your heating and cooling utility bills as well as blown cellulous insulation, batted insulation, fiberglass insulation.]