A rigid insulating phenolic foam body (8) has at least one perforated facing (1). The facing (1) is preferably perforated before the facing (1) is adhered to the foam body. The facing (1) may be 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.
