Tetrastyle: See Portico.
Tholos: a building of the beehive type, circular in plan, with a domed roof.
Thrust: a strain that tends to push the downward pressure toward the sides; as in the case of an arch.
Tie-Beam: in timber roof construction, the transverse beam that ties together the lower part of opposite rafters.
Tierceron-rib: See Rib.
Tile: a thin piece of terra-cotta, stone, or marble for the external covering of roofs.
Torus: a large convex (usually semi-circular) moulding used especially in bases of columns. See Astragal.
Trabeated: having a horizontal Beam or Entablature.
Tracery: the pattern of stonework that fills the upper part of a Gothic window. Distinguished as Plate Tracery, where the tracery looks as if it were pierced in a single plate or slab of stone; Bar Tracery, when composed in an arrangement of geometric designs. The German imitation of branches is known as Branch Tracery.
Transepts: the parts of a church or cathedral that project at right angles to the nave and choir, forming the arms of the Cross in a Cruciform (which see) plan.