GreenGuard XP38 Fanfold Underlayment

Kingspan's premium choice ⅜” (0.375") thick closed-cell extruded polystyrene (XPS) fanfold underlayment with our best-perforated facers on both sides for use in replacement siding operations; is 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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