Segmentation by type distinguishes open‑cell and closed‑cell flame‑retardant rigid polyurethane foams, each with distinct sub‑categories that shape market dynamics. Open‑cell foams, typically low‑density (≈30–45 kg/m³), are favored in interior insulation where breathability and cost efficiency are paramount; they contribute roughly 40 % of the type‑based market due to widespread use in wall and roof panels. Closed‑cell foams, higher density (≈80–120 kg/m³), offer superior moisture barrier properties and are split into high‑density and medium‑density sub‑types. High‑density variants, comprising about 30 % of the type segment, serve structural sandwich panels and marine hulls, while medium‑density foams (≈20 %) address automotive and appliance interiors. Emerging bio‑based and silicone‑modified formulations, each representing ~5 % of the total, address sustainability mandates and extreme‑temperature applications respectively. The relative weight of these sub‑types reflects regulatory pressures, performance requirements, and cost considerations, thereby delineating the overall market size for flame‑retardant rigid polyurethane foam.