Fire retardant coating systems and solid body cast systems comprise a first part comprising at least one ingredient having NCO functionality; and a second part comprising at least one ingredient having an active hydrogen functionality that is co-reactive with the NCO, wherein the first part and the second part are formulated so that when the parts are mixed together they form a cured coating or a solid body. The coating system or solid body cast system comprises a first fire retardant ingredient that is a phosphorus-based compound, a second fire retardant ingredient that is an intumescent material, and a third fire retardant ingredient that is a brominated ingredient. Methods for preparing a fire retardant coating or solid body are also described.