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.
History Dropped ceilings and ceiling tiles were used in Japan for aesthetic reasons as early as the Muromachi Period (1337 to 1573).Interview with Matthew Welch, Curator of Japanese and Korean Art, Minneapolis Institute of Arts , retrieved January 12, 2014 These could be made with simple planks, or coffered. Blackfriars Theatre in London, England, built in 1596, had dropped ceilings to aid acoustics.The Acoustic World of Early Modern England by Bruce R. Smith, page 216, retrieved January 14, 2014
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.Suspended Ceiling Patent, retrieved January 14, 2014 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 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.Patent US 2,984,946 A - Accessible Suspended Ceiling Construction, retrieved January 12, 2014 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.
+ U. S. dropped ceiling patents to September 8, 1958 Date filed Patent no. Applicant Title Comments May 28, 1919 1,470,728 Hall Suspended Ceiling September 3, 1931 1,931,574 Danielson Suspended Ceiling Hanger October 24, 1950 2,710,679 Bibb, Remmen, Bibb Suspended Ceiling Construction First fully developed grid system concept December 13, 1955 2,816,623 Wong Modular Ceiling First integration of tiles and grid. Wong founded Cepco Manufacturing, a company later absorbed into Ceilume, a division of Empire West, Inc. May 11, 1956 2,896,752 Wilde Suspended Ceiling Grid Construction July 31, 1956 2,894,291 Sorenson Suspended Ceiling System October 25, 1956 2,895,180 Byssing Suspended Ceiling February 7, 1958 2,963,251 Fuss Supporting Electric Lighting Fixture from Suspended Ceiling Framework September 8, 1958 2,984,946 Brown Accessible Suspended Ceiling
Design objectives 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.New Trends in Ceiling Designs and Materials, retrieved January 15, 2014
Aesthetics 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.
For many years, dropped ceilings were made of basic white tiles, but modern innovations now offer a plethora of options in sizes, colors, materials (including retro designs and faux leather, wood, or metal), visual effects and shapes, patterns, and textures as well as support systems and ways to access the plenum.Ceiling Technology and Aesthetics , retrieved January 15, 2014 Custom runs of specialty ceiling tiles can be done at relatively low cost compared with the past.
Acoustics Acoustic balance and control was another early objective of dropped ceilings.Suspended Ceiling Construction, retrieved January 15, 2014 The acoustic performance of suspended ceilings has improved dramatically over the years, with enhanced sound absorption and attenuation. This is sometimes achieved by adding insulation known as Sound Attenuation Batts (SABs), more commonly referred to as "sound batts", above the panels to help deaden sounds and keep adjacent rooms quieter.Let us Talk about Dropped Ceilings , retrieved January 15, 2014
Environmental factors
Indoor environmental quality Indoor environmental quality includes ventilation, VOC emissions, lighting and thermal system control, thermal comfort, use of daylight for natural illumination, acoustics, and optimization of outdoor view availability.
Sustainability Many manufacturers of modern dropped ceilings include sustainability as an objective. Sustainable features may include: Energy efficiency, including daylight efficacy and thermal insulating qualities. This uses the ceiling plane to reflect daylight as well as electrical illumination to maximize lumen efficacy, which also improves the comfort and usability of interior spaces. A common measure of the light reflectance of a ceiling material is ASTM E 1477 for Light Reflectance (LR-1). A level of about 75% is considered good, although higher levels are possible. Reduced resources needed for construction of the tiles Recyclable/reused/renewable materials
Integration with infrastructure Integration with mechanical, electrical, and plumbing (MEP) is important with dropped ceilings, since most of these systems are by definition above the ceiling. Most ceiling system products are now designed with this integration in mind. Decisions here can also affect aesthetics as well as access and maintenance.
Cost Dropped ceilings are likely to cost more to install than an open plenum, but may offer significant cost savings in maintenance and energy.Life Cycle Analysis: Wall-to-Wall Ceilings and the Open Plenum--Energy Savings and Other Benefits of Suspended Ceilings vs. Open Plenum, retrieved January 15, 2014
Suspension grids A typical dropped ceiling consists of a gridwork of metal channels in the shape of an upside-down "T", suspended on wires from the overhead structure. These channels snap together in a regularly spaced pattern of cells. Each cell is then filled with lightweight ceiling tiles or "panels" which simply drop into the grid. The primary grid types are "Standard1" (-inch face), Slimline (-inch grid), and concealed grid.
In the United States and its neighboring countries, the cell size in the suspension grids is typically either or , and the ceiling tiles, light fixtures, and fluorescent light tubes are the same size. In Europe, the cell size in the suspension grids is 600×600 mm, while the ceiling tiles and fixtures are slightly (5 mm) smaller at or , and the T5fluorescent and LED tubes are shorter by 37 mm to allow for easier and safer insertion and removal without breakage.
Concealed grid
An older, less common type of dropped ceiling is the concealed grid system, which uses a method of interlocking panels into one another and the grid with the use of small strips of metal called "splines". Normally, they have a "key panel" (usually in the corner) that can be removed, allowing for the other panels to be slid out of the grid (a series of metal channels called "zbars") one by one, until eventually removing the desired panel. This type of ceiling is more commonly found in older installations or installations where access to above the ceiling is generally considered unnecessary.
This system has some major disadvantages compared to the more common "drop panel" system, notably the difficulty in removing and reattaching panels from the grid, which, in some cases, can cause irreparable damage to the panels removed. Finding replacement panels for this type of dropped ceiling is becoming increasingly more difficult as the demand for them and the production of parts slow. Small clips are available that allow tiles to be inserted into gaps in the ceiling where a tile is missing and work by being placed on the edge of a concealed tile and then being slid along as the tile is placed to lock it in place.
Stretch ceiling
With similar advantages to a dropped ceiling, a stretch ceiling is often used to conceal pipework, wires or the existing ceiling. There is also usually a broad choice of colour or texture, and the membrane can be manipulated into a variety of shapes.
A stretch ceiling is a suspended ceiling system and it is made of three main components: Perimeter track – Aluminium or plastic PVC Membrane – Typically a PVC or nylon material, lightweight sheets are made to size/shape from roll material. Can be printed or painted to achieve the desired effect. Harpoon or catch – This is ultrasonically welded to the edge of the membrane or sheet in the factory, the edging slots into the perimeter track to keep the ceiling in place.
When a stretch ceiling is being installed, semi-concealed plastic/aluminum track, the preferred choice for most architects and designers, is cut to size and fixed to the perimeter of the ceiling area. The membrane is stretched and the harpoon or catch edge is clipped into the track. Stretching is aided by heating up the membrane or sheet prior to fitting.
Drop out ceilings
Approved drop out (or drop-out) ceilings allow the installation of a dropped ceiling beneath existing fire sprinklers because the tiles, sometimes called melt-out ceiling tiles, are heat-sensitive and are designed to fall from the dropped ceiling suspension grid during a fire, allowing the sprinklers to spray their water.
Drop out ceiling tiles can add to the aesthetic appeal of a ceiling since the fire sprinklers are hidden by the tiles. Commonly made from vinyl or expanded polystyrene, drop out ceiling tiles are available in multiple sizes and finishes from a variety of manufacturers.
Installation is subject to the local Authority Having Jurisdiction (AHJ) and, in the United States, must meet the standards listed in the section below at a minimum.
Drop out ceiling standards (United States) The following standards are in addition to those for ceiling tiles in general. No clips, fasteners, or impediments of any kind can be used to limit the ceiling tile's ability to drop from the suspension system without restraint in the event of a fire unless they have been used in the testing process. Painting can void an approval, and additional local requirements may exist.
FM Global – Approval Standards for Plastic Suspended Ceilings, retrieved January 15, 2014 UL – Ceiling Panels for Use Beneath Sprinklers, retrieved January 15, 2014 ICC-ES – AC-12 Section 4.4 – Foam Plastic Drop-Out Ceiling Panels and Tiles, retrieved January 15, 2014 NFPA 13 – Standard for the Installation of Sprinkler SystemsNFPA 13: Standard for the Installation of Sprinkler Systems, retrieved January 15, 2014
Safety issues
In older buildings, the space above the dropped ceiling was often used as a plenum space for ventilation systems, requiring only enclosed ducts that deliver fresh air into the room below, with return air entering the ceiling space through open grilles across the ceiling. That practice is now used less frequently in new buildings.