A significant percentage of the gypsum board used in non-residential construction is incorporated into fire-resistance-rated assemblies. The majority of the rated walls or partitions constructed with gypsum board in the U. S. and Canada contain “Type X” gypsum board or an improved variation with a proprietary trade name. A handful of systems that use regular core gypsum board to create a rated system still exist; however, they are generally antiquated and supporting documentation can be difficult to obtain.
Similar to regular core board, Type X gypsum board is manufactured in accordance with ASTM Standard C 1396, Standard Specification for Gypsum Board. Specific language in the C 1396 standard establishes the criteria for determining Type X compliance for individual board products.