Abstract: An under floor insect control method for structures in which an insect control chemical in a mixed resin foam coating is installed under the floor by forcefully mixing, at a nozzle part of the sprayer, and spraying on the soil surface the following: an aqueous emulsion, of which 15-20 percentage by weight is a solid copolymeric resin, based on vinyl acetate and alkyl methacrylate in a proportion ranging from 55-85 and 15-45 parts by weight, respectively; an inert organic solvent solution contains a mixture of diisocyanate and polypropylene glycol in a proportion ranging from 5-15 and 85-95 parts by weight, respectively. The two components make up an adjusted 60-80 percentage by weight as a total volume. An insect control chemical is also included. The proportion of organic solvent solution to the emulsion is in the range of 7-15 percentage by volume. The mixed resin foam insect control barrier formed provides superior insect control chemical immobilization, gas barrier and crack proof properties.