ICC 1125 - 2026 Standard for Classification of Magnesium Oxide Board and Constructionater

Magnesium oxide (MgO) boards are rapidly emerging as an important alternative material in modern construction, offering durability, versatility, and potential sustainability benefits across a range of applications. The ICC 1125-2025 Standard for Specification of Magnesium Oxide Board and Construction provides the first comprehensive, consensus-based performance standard for MgO boards in North America. Developed through ICC’s ANSI-accredited process, this groundbreaking standard establishes clear testing requirements, classifications, and performance criteria to support safe, consistent, and code-aligned use of MgO board products in residential and commercial buildings. Covering everything from fundamental material properties to application-specific structural performance, ICC 1125 equips manufacturers, designers, installers, and regulators with a trusted resource for evaluating products and ensuring high-quality construction outcomes.

Includes information on the following:

• Scope, definitions, and administrative provisions for classifying MgO board products
• Minimum physical property and durability requirements for all board types
• Comprehensive performance testing protocols, including flexural strength, moisture movement, freeze–thaw durability, corrosion resistance, impact resistance, and surface burning characteristics
• Application-specific requirements for wall sheathing, tile backer, floor sheathing, and roof sheathing
• Optional provisions for fire-resistance-rated construction and noncombustible recognition
• Criteria for structural racking shear performance in wood and cold-formed steel light-frame construction
• Requirements for braced wall panel equivalency under the International Residential Code
• Identification, labeling, and quality control specifications for manufacturers
• Clear guidance to jurisdictions for adoption, interpretation, and ongoing maintenance of the standard