ASTM C844-15 (R2021) PDF Download

ASTM C844-15 (R2021) defines the minimum requirements and procedures for applying gypsum veneer base for use with gypsum veneer plasters. The standard emphasizes the importance of obtaining construction details from fire-resistance tests, engineering evaluations, or recognized fire testing laboratories to achieve the required fire resistance for a specific assembly. The specification classifies various materials, including gypsum base for veneer plasters, gypsum backing board for coreboard, special fire-retardant gypsum base, foil-backed gypsum base, gypsum veneer plaster, nails, non-load bearing steel, load-bearing steel, steel framing (load-bearing and non-load bearing), accessories, adhesives, and wood framing.

The standard specifies the maximum spacing of framing members for single gypsum base construction and provides instructions for various methods of application, such as single-ply gypsum base, adhesive-mechanical fastener, foil-backed gypsum base, two-ply gypsum base, and application over existing surfaces. It also outlines the requirements for solid gypsum base partitions, including face ply, core, and runners. Furthermore, it states that direct adhesive application should be limited to interior masonry or concrete walls above grade or inside exterior masonry cavity walls.

Gypsum base application over steel framing and furring requires adherence to specific screw application, framing space, and screw spacing. Additionally, when applying gypsum base to the soffit of arches, the standard stipulates that it should be carefully bent into place and conform to the specified bending radii.

The standard includes additional sections that address topics such as the unsuitability of gypsum veneer base for tile application in areas with abnormal moisture, humidity, or temperature; the requirements for achieving specific degrees of sound control in veneer plaster assemblies; and the need for proper ventilation in unheated spaces above gypsum veneer base ceilings. It also clarifies that the referenced notes and footnotes in the standard are for explanatory purposes and not requirements.