Your local insulation contractor! Servicing Mendocino, Sonoma, Lake & Marin Counties. Founded in 1982 primarily as an insulation company, Apperson Insulation has evolved over the last 30+ years to become a leader in local building performance and insulation contracting. As building standards have changed, energy efficiency measures have become more important, and our understanding of building science has grown. This company continues to be on the cutting edge of home performance.