Room where the tea ceremony is performed or sometimes a whole building where such a room is the center. Styles can broadly be divided into the *shoin 書院 style tearoom and the rustic *sōan 草庵 style tearoom. The most common size is 4 1/2 mats *yojōhan 四畳半. A tearoom of more than 4 1/2 mats is called *hiroma 広間, and a smaller tearoom is called *koma 小間. The composite elements of the chashitu are a decorative alcove *tokonoma 床の間, and separate entrances for the guest and for the host.
Straw mats *tatami 畳 cover the floor, and these are distinguished as mats for guests *kyaku datami 客畳, the mat used by the host *temae datami 点前畳, and the mat for placing the utensils used during the ceremony *dōgu datami 道具畳. The host's mat is usually 3/4 of the standard size *daime datami 台目畳, but guests may have the use of one, two, or three mats, and each has a name according to its place and use.
The correct position for the hearth *ro 炉 is considered to be within the host's mat or between dōgu datami and a guest's mat. The combination of the above elements have produced numerous chashitsu plans, each plan reflecting the taste of a tea master. The tea ceremony room also is called chaseki 茶席, *sukiya 数寄屋, *kakoi 囲, *kozashiki 小座敷.