One of the most significant gypsum board system successes of the modern (i.e., post-World War II) gypsum board era, however, was actually a very simple adaptation of a previously developed product. That system is the gypsum board townhouse separation wall system (or as it is known in some regions, the area separation wall system).
Gypsum board townhouse separation wall systems are direct descendants of the gypsum board shaftwall systems that were first introduced into the non-residential marketplace in the '60s. Shaftwall systems use gypsum board liner panels placed between metal studs to create strong, durable duct and elevator shafts for use in high-rise buildings. In the '70s, the concept of using liner panels placed between studs was adapted to residential townhouse construction and the townhouse separation wall was born.