Many common building materials have the potential for damage when exposed to very high humidity or condensation. DuPont™ ArmorWall™ Plus System panels are delivered with a pre-applied weather resistive barrier (WRB) on the outer surface, and high-performance foam insulation bonded to the MgO board via patented Fusion Technology on the back. Both components slow the uptake of water vapor to limit exposure of the MgO to water during periods of high humidity, while allowing the assembly to dry out once the external relative humidity drops. As such, typical applications using vented or rainscreen cladding types can be used in all climate zones.

In applications that involve continued exposure to very high humidity (e.g. indoor pools), appropriate modeling tools should be used to understand the potential for buildup of excess water in the assembly. Contact DuPont for technical assistance with these applications.

Corrosion is always present on jobsites. Industry practices and materials such as galvanized studs have mitigated issues in construction with a well-designed building envelope. Materials like wood or MgO can degrade when exposed to water and should be protected. Failure to protect MgO used as exterior sheathing, or any use of poor quality MgO, could cause degradation of the MgO structure and increase the risk of ions leaching (chloride or sulfate). Metal parts exposed to leached ions are likely to corrode more quickly. Therefore, only high quality MgO is recommended for exterior sheathing applications and contact with water should be mitigated.

The outer MgO layer in ArmorWall™ panel comes with a water-resistive barrier that helps prevent extended exposure to bulk water. MgO used in ArmorWall™ panels is thoroughly tested for stability in high humidity conditions and does not contribute additional corrosion to other building components, such as galvanized studs. In most cases, the continuous insulation layer of ArmorWall™ is in contact with the framing.

Due to the wide variety of fasteners available, it is important to avoid corrosion-prone fasteners to attach the panels or the cladding. The recommended fasteners for the ArmorWall™ System are either stainless steel or tri-coated, both of which offer high corrosion resistance.

MgO based exterior sheathing panels can be used in place of gypsum sheathing in most wall assemblies and building types. While both exterior sheathings can be used to provide a reliable air barrier when joints between boards are treated and are integral to a variety of fire-resistive wall assemblies, MgO based exterior sheathing provides advantaged performance.


Direct attachment of cladding rails, girts, strapping, etc., without the need to fasten back to the studs.
Some MgO based exterior sheathing panels, like DuPont™ ArmorWall™ System panels, are supplied with factory applied water resistive barrier and/or insulation layers, adding functionality beyond gypsum-based sheathing for construction efficiencies.
MgO based exterior sheathing panels do not support mold growth (ASTM C1338), and do not use paper facers further reducing risk of mold growth.

Very few MgO boards are classified as strictly non-combustible when evaluated using ASTM E136 as referenced in the International Building Code. In practice, MgO boards perform very well in large-scale fire testing due to the superior fire resistance of hydrated inorganic MgO cement that makes up over 90% of the boards.

The fire performance of the full ArmorWall™ system has been demonstrated by multiple NFPA 285 and ASTM E119 test results, providing significant opportunities for multiple wall design configurations to address project needs for all construction types. Refer to ICC-ES ESL 1442 for ArmorWall™ NFPA 285 compliance options and ICC-ES ESL 1302 for various ArmorWall™ fire-rated wall assemblies.

Tools commonly found on construction projects, such as circular saws and reciprocating saws can be used. Refer to the ArmorWall™ installation manual for cutting and installation instructions for the ArmorWall™ System.