Seismic floor expansion joint for large movements, comprising the side angle sections and a central plate made of stainless steel, able to take up expansion and contraction movements, as well as vertical shearing movements. Suitable for all types of hard floors (tiles, stone, marble, etc.), but can also be used with flexible floors or carpet. For indoor and outdoor floor joints with a gap up to 200 mm, with large amount of movements. Suitable for traffic of pedestrians and light trolleys. Floor-to-floor type only. The central plate takes the mortar on which the floor covering in laid. Once the floor covering is laid, the joint is practically invisible; only two stainless steel sections remain exposed. Waterproof membrane as option, with possibility of integrating drainage system to recover the liquid. STF joints can be matched to vertical joints of similar finish and with the same movement range.