DuPont™ Thermax™ Sheathing Polyisocyanurate Insulation is a non-structural, rigid board insulation consisting of a glass-fiber-infused polyisocyanurate foam core laminated between 1 mil smooth, reflective aluminum facers on both sides. The glass-fiber reinforcement contributes to improved fire performance and dimensional stability.

Thermax™ Sheathing Insulation also offers high, long-term thermal resistance, with facers that help prevent water and water vapor intrusion into the insulation foam allowing it to stabilize at a higher R-value. In the USA, Thermax™ Sheathing can be installed as exterior continuous insulation and also installed exposed to the interior without a thermal barrier. Used in conjunction with the appropriate joint closure system for the application, Thermax™ Sheathing – with its low perm rating – can help to reduce moisture condensation within and behind the insulation.