The design of highway or airport pavements may be governed by subgrade stress/deformation criteria or frost heave protection requirements. Where the pavement thickness is controlled by frost heave conditions considerable savings can be realized by installation of geofoam as insulation. In considering geofoam as a subgrade insulation element, care should be exercised to minimize development of differential icing. Available experience suggests that the performance of geofoam insulation depends on tight construction control to ensure continuity of insulation without gaps. High density geofoams provide higher initial R-values, deform less under load, and absorb less moisture over time.