Factory-built grease ducts have been around for about 20 years, dovetailing with the general trend in construction toward prefabricated, modular components. Over the years, factory-built grease ducts have gained a small but growing share of the market, because of their modularity and the elimination of on-site welding. Use of these manufactured grease ducts has lagged over the years because of the higher direct cost and the additional requirement of a ventilated, fire-rated enclosure, or chase.
The newest generation of manufactured grease ducts, however, features better insulation, permitting zero clearance to combustibles, and eliminates the need for a fire-rated enclosure. This makes the cost/benefit analysis much more competitive and presents building owners with a better alternative to conventional welded grease ducts.