A method for manufacturing a rigid insulating phenolic foam body 8 having at least one perforated facing 1. The facing 1 is perforated before the facing 1 is adhered to the foam body. The facing 1 is a gas impermeable material such as a metallic foil. The perforations 5 in the gas impermeable material reduce the drying and curing time for phenolic foam bodies when compared with phenolic foam bodies with gas permeable facings.
