Johns Manville | 68,557 followers on LinkedIn. At Johns Manville, we build on decades of experience to manufacture commercial roofing, premium-quality insulation and a variety of engineered products for our customers. We are proud to be part of Berkshire Hathaway, one of the most respected companies in the world. Our values of People, Passion, Perform and Protect drive the way we work as we strive to deliver positive and powerful JM Experiences to our employees and to our customers.