Types of Chimneys Masonry Chimneys. What we usually picture when we think about chimneys is a masonry chimney: one constructed of brick, concrete blocks, or stone. But current building technology includes another major category, the factory-built chimney. Factory-Built Chimneys. Builders and remodelers can now choose from a wide variety of chimneys constructed of metal and other materials. These chimneys are manufactured in a factory and assembled at the site. Among the more popular types of factory-built chimneys are: Double-wall, mass-insulated chimneys. Two layers of metal, generally stainless steel, with an insulative material between the layers of metal. Picture a pipe inside a larger pipe, with the space between the two packed with insulation. Air-cooled chimneys. Two or more layers of metal with air in between, constructed so that the air circulates between the layers, dissipating the heat. Air-insulated chimneys. Similar to the air-cooled design, except it is constructed for minimal movement of air between the layers, so the air acts as an insulator instead of drawing heat away. Combinations. Chimneys which incorporate a combination of mass-insulation, air-cooling and/or air insulating designs.