china's fire department announced on december 3 that no. 65 document had been cancelled and no. 46 document would be reexecuted. grade a materials is no longer forcibly required in building insulation and materials of grade b1 and b2 would be suitable for roofing.
no.65 document of ministry of public security, launched on march 14, 2011, strictly regulates that the building insulation materials combustion performance shall not be lower than b2.
according to some insulation materials suppliers, combustible material is largely used in building insulation since it enjoys advantage in price although fireproof performance is not good as that of incombustible material, being economical is the absolute principle in most projects.
for instance, rock wool, a kind of grade a material, priced at rmb 1300/ton at current time, when it is applied to exterior wall insulation, cost achieves to rmb 130/㎡; extruded sheet, belongs to grade b2 combustible material, is quoted around rmb 400/stere, cost is just reaching rmb 40/㎡ when applied to exterior wall insulation, 1/3 lower than that of rock wool.