To provide a heat-insulating structure capable of directly sticking a gypsum board to a heat-insulating layer made of an on-site spray type urethane foam formed on a surface of a concrete skeleton and not adversely affecting adhesion, dimensional change, non-combustibility, etc. A three-layer structure a is provided in which a heat insulation layer 10, a primer layer 20, and an adhesive layer 30 are formed in this order from an indoor side surface of the concrete skeleton B toward the indoor side. The heat-insulating layer 10 is formed of a mixture of a polyisocyanate compound, an ester-based polyol compound, a trimerization catalyst, an additive, Wherein the additive contains at least a foaming agent and an acrylic surface modifier and does not contain a silicon-based foam stabilizer, and the additive contains red phosphorus as an essential component, A method for producing a foam, comprising: Forming a foam of an on-site spray...
