Abstract: An insulating and protective structure for frozen substrates wherein a hydrophobic or water impermeable base layer is applied first to the substrate and successive layers of a polyurethane foam or similar synthetic plastic foam material are foamed in place on the base layer, each of said foam layers having a vapor penetration-resistant layer on its upper surface and below the next layer of foam. Finally, there is applied a hydrophobic or water impermeable layer to the upper surface of the uppermost vapor penetration-resistant layer.This structure is designed particularly for application to substrates underlain with permafrost in the Arctic and sub-Arctic regions. It is designed to provide moisture penetration resistance, low thermal conductivity and to have both high compressive and flexure strength in order to impede heat transfer even with consequent freeze-thawing of the frozen substrate and likewise prevent physical damage to the surface of the substrate.