The insulation performance and fire safety of steel structure factories and cold chain warehouses depend largely on the core material inside sandwich panels. The five mainstream options are rock wool, polyurethane (PU/PIR), EPS, slag wool, and glass wool. They differ significantly in fire resistance, temperature tolerance, thermal conductivity, and smoke safety.

☆High-Quality Rock Wool (Class A Non-Combustible)

No toxic smoke when exposed to flames; ensures safe evacuation

Withstands up to 600℃; fire resistance 30-240 minutes

Thermal conductivity: 0.036-0.043; stable insulation

Best overall performance and versatility; ideal for most permanent industrial buildings; high acceptance rate

☆EPS (Class B Flammable)

Produces heavy black toxic smoke; major fire hazard

Maximum service temperature: only 85℃; prone to deformation

Thermal conductivity: 0.039-0.041; basic insulation only

Limited to temporary structures; banned from permanent buildings; frequently fails inspections

☆Polyurethane PU/PIR (Class B Flammable)

Produces black smoke when burning; withstands only 170℃

Thermal conductivity: 0.022-0.024; best insulation among all five

Preferred for cold chain buildings, but must pair with rock wool at fire partitions and evacuation routes

☆Slag Wool (Class A Non-Combustible)

No toxic fumes, but weaker than rock wool overall

Withstands only 300℃; fire resistance under 60 minutes

Thermal conductivity: 0.038-0.048; low insulation efficiency

Fibers tend to powder and settle over time; suitable only for low-budget, non-critical projects

☆Glass Wool (Class A Non-Combustible)

Smokeless and non-toxic; withstands 200℃; fire resistance 30-120 minutes

Thermal conductivity: 0.033-0.043

Poor moisture resistance; insulation drops sharply when wet

Rarely used in walls/roofs; mainly for duct insulation and light partitions

Selection Guidelines

Cold chain storage: use polyurethane for the main enclosure and rock wool for fire partitions

Standard factories, large warehouses, high-risk buildings: choose high-quality rock wool

Temporary sites: EPS is acceptable; avoid for permanent projects

Duct insulation: glass wool works well

Low-budget, low-heat small buildings: slag wool may be used short-term

Polyurethane leads in insulation but lacks fire safety. EPS is cheap but highly hazardous. Slag wool and glass wool have durability and application limits. High-quality rock wool delivers the best balance of fire safety, heat resistance, and long-term insulation, making it the most versatile choice. Material selection must consider fire codes, operating temperatures, and project lifespan,not just insulation efficiency or cost. This approach prevents inspection issues and long-term safety risks.

For more information needed or any inquiry,please feel free to contact Yumisteel team.