
GreenGuard XP38 Fanfold Underlayment
Premium level ⅜” XPS fanfold with our best facers, cut-and-fold hinges


Kingspan's premium choice ¼” (0.25") thick closed-cell extruded polystyrene (XPS) fanfold underlayment with our best perforated facers on both sides for use in replacement siding operations; designed to be used as a “leveling board”, adding insulation and moisture protection in installation of new vinyl siding over old siding. It is configured in fanfolded bundles 4’ x 50’ with cut-n-fold hinges which improves its ability to lay flat. It is lightweight, easy to cut, and install.
Product Highlights
Kingspan's top-of-the-line facers
Lay flat cut-and-fold hinges
Perforated to allow moisture vapor to escape

Premium closed-cell extruded polystyrene (XPS) fanfold underlayment with perforated facers on both sides for use in replacement siding operations.