False ceiling

A dropped ceiling is a secondary ceiling, hung below the main (structural) ceiling. It may also be referred to as a drop ceiling, T-bar ceiling, false ceiling, suspended ceiling, grid ceiling, drop in ceiling, drop out ceiling, or ceiling tiles and is a staple of modern construction and architecture in both residential and commercial applications.

Dropped ceilings and ceiling tiles were being used in Japan for aesthetic reasons as early as the Muromachi Period (1337 to 1573).Blackfriars Theater in London, England, built in 1596, had dropped ceilings to aid acoustics.

U. S. Patent No. 1,470,728 for modern dropped ceilings was applied for by E. E. Hall on May 28, 1919 and granted on October 16, 1923. Initially modern dropped ceilings were built using interlocking tiles and the only way to provide access for repair or inspection of the area above the tiles was by starting at the edge of the ceiling, or at a designated "key tile", and then removing contiguous tiles one at a time until the desired place of access was reached. Once the repair or inspection was completed, the tiles had to be reinstalled. This process could be very time-consuming and expensive. On September 8, 1958 Donald A. Brown of Westlake, Ohio filed for a patent for Accessible Suspended Ceiling Construction. This invention provided suspended ceiling construction in which access may readily be obtained at any desired location. Patent Number US 2,984,946 A was granted on May 23, 1961. Brown has sometimes been credited as being the inventor of the dropped ceiling even though other patents preceded his as shown in the table below.

(To search for U.S. patent images, go to https://www.google.com/?tbm=pts and enter the patent number in the search box.)

Effective building design requires balancing multiple objectives: aesthetics, acoustics, environmental factors, and integration with the building's infrastructure—not to mention cost of construction as well as long-term operation costs.

Modern dropped ceilings were initially created to hide the building infrastructure, including piping, wiring, and/or ductwork, by creating a plenum space above the dropped ceiling, while allowing access for repairs and inspections. Drop ceilings may also be used to hide problems, such as structural damage. Further, drop out ceilings can also conceal the sprinkler systems while still providing full fire suppression functionality.

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Wikipedia