PURPOSE: To form the title flowable filler for filling up a gap between members, which can be filled into even a narrow gap and, in case of fire, foams to reveal excellent fireproofness and smokeproofness, by using a specified composition.
CONSTITUTION: The title flowable filler for filling up a gap between members, consists of a fireproof filler body (e.g. silicone) having a thermally foamable particulate material and a particulate heat insulating material dispersed therein, in which the thermally foamable particulate material contains at least a hydrous salt (e.g. hydrous sodium silicate) and a heat-decomposable foaming agent (e.g. azobisisobutylonitrile), in which the particulate heat insulating material consists of a material of at least sub-nonflammable grade, composed mainly of a vinyl chloride resin (e.g. PVC) or chlorinated vinyl chloride resin containing an inorganic filler (e.g. glass fiber).