M-D Building Products, Inc. has a rich history of product development and manufacturing expertise. Beginning in 1920 as Macklanburg Duncan, the M-D story encompasses over 90 years of inventing and manufacturing products demanded by our customers. Our products are industry leaders or contend for industry leadership in the categories of weatherization, flooring tools, flooring accessories and digital levels. M-D Building Products began in the weatherization and home sealing industry. While one of the nation’s oldest such companies, it continues to lead the weatherization industry in realizing better and more sustainable channels for more comfortable living. M-D is focused on creating a healthier environment and conserving our natural resources through all of its complementary businesses: weatherization, flooring tools and accessories, digital levels and engineer OEM products.