Abstract: A foam composite--especially useful as an insulating board--comprising first and second opposed corrugated skins having corrugations with inwardly facing apices, one or each of the skins being provided with a mat of porous or apertured reinforcement material extending across the apices of the corrugations and the foam extending through the pores or apertures of each mat to fill the spaces defined by the inwardly facing surfaces of the corrugations and embed the reinforcement material within the cured foam. As an alternative to a continuous mat, there may be used a plurality of strips of rigid porous or nonporous reinforcement material, spaced apart and extending across the apices of the corrugations, the foam extending through the gaps between the strips to fill the spaces defined by the inwardly facing surfaces of the corrugations and embed the strips of reinforcement material within the foam. The mat or strips reinforce the skin and resist dimensional change due to shrinkage of the foam core during storage.