Tatami mats are traditional flooring typically used in Japanese rooms. Each mat consists of three layers: the base (tatami-doko) made from compressed rice straw, the outer layer (tatami- omote) made from igusa (rush), and the border (tatami-heri) typically now made using synthetic fibers.
Most traditional tatami mats use 100% natural rice straw to create the base, with certain characteristics, such as quality of the rice straw and rate of compression, determining the quality of the mats. The highest quality mats are usually reserved for use in tea rooms and at religious sites, such as buildings located within Buddhist temples and Shinto shrines, with some lasting several centuries. Some manufacturers currently prefer to use a sheet of Styrofoam which is more cost effective and provides better insulation and humidity control. Igusa quality is also determined by length and how it is weaved, with the highest quality again reserved for religious sites. Linen and cotton are typical materials used in the weaving process.