Polystyrene?boards are better in terms of external wall thermal insulation materials but now polystyrene?boards are not allowed to use. Rock wool and glass wool can be used, but they need good waterproofing treatments.
According to the "Provisional Regulation of Civil Building External Thermal Insulation System and Exterior Wall Decoration Fire Prevention" issued by Ministry of Public Security and Ministry of Housing and Urban-Rural Development, the fireproofing performance of it should not be lower than B2-level. Rock wool board and glass wool are both accessible if taking cost into consideration. The combustion performances of polystyrene?boards are generally C- and B1-level, while the combustion performance of external wall thermal insulation materials should be A-level.
