Dropped ceilings are secondary ceilings designed to hang below a structural ceiling. The dropped ceiling is installed as a grid that attaches to the structural ceiling. After the grid is installed, it is filled with lighting fixtures and ceiling tiles made or acoustical materials. The grid can be divided into square or rectangular spaces depending upon the look the architect or designer wants the ceiling to have. Sometimes ceiling tiles are cut or punctured to hold irregular or round-shaped lighting fixtures. Other times the designer may specify a light fixture that fills a grid opening without the need for a tile. Most designers follow specific needs when choosing the number and placement of light fixtures and ceiling tiles.
There are two standard sizes for a dropped ceiling tile: 2-by-2 feet and 4-by-4 feet. The ceiling tiles match the size of the ceiling grids available in the marketplace. Specialty ceiling tile is usually made in one size, 2-by-2-feet. Textured tiles such as the fissured or dimensional tile, sometimes referred to as a regular tile, are manufactured in both square and rectangle sizes. Since rooms are not always shaped to match a full sized ceiling grid, tiles can be cut to fit the grid where needed.
Ceiling tile manufacturers design tile products for both commercial and residential installations, making the selection available varied and broad. Tiles can be used in either industry as long as the tile's fire rating matches the needs of the space being built — check local building codes through your city or county government's building and construction office to verify. Manufacturers use a variety of materials to make ceiling tiles including mineral fiber — made from a byproduct of the steel industry called wool slag, fiberglass fibers and perlite.
Typical tile styles include a variety of textures such as fissured — a lightly punctured texture -- and dimensional, which provides a stepped appearance around the edges of each tile. Specialty dropped ceiling tiles are designed to represent traditional ceiling styles such as coffered, bordered and metal ceilings. Special sizes may be negotiable, depending upon the manufacturer's requirements that usually include a specific number of tiles per custom size order. It is important to paint dropped ceiling tiles only per the instructions of the manufacturer, to maintain the product warranty.