A prefabricated chimney is made from metal and is an alternative to a traditional masonry chimney, which is made from mortar and brick. Prefabricated metal chimneys have been available since the 1980s and are typically used with prefabricated fireplace systems. When it comes time to select fireplace systems for their remodeled or newly constructed homes, homeowners should be aware of the pros and cons of prefabricated chimneys.