If preferred, the surface of the insulation board can be painted. Rmax recommends a quality grade acrylic latex paint. While primer is not generally required, consult the paint manufacturer and/or industrial paint supply for recommendations and best practices.
How do you install Thermasheath insulation?
Thermasheath®-3 may be installed horizontally under foundations and vertically inside of the footings. A separate vapor retarder sheet should be installed over or under the insulation against the crushed stone base and well tamped backfill or undisturbed earth. Simply lay in the insulation with tightly butted joints.