GreenGuard XFP38 Fanfold Underlayment

Premium choice ⅜” (0.375) thick closed-cell extruded polystyrene (XPS) fanfold underlayment with reflective surface on one side for added energy efficiency 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.

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