What is a commonly accepted percentage of water incorporated in gypsum walls?

Gypsum walls, commonly known as drywall or gypsum board, typically contain a significant amount of water as part of their chemical composition. The dominant mineral in gypsum is calcium sulfate dihydrate, which consists of two water molecules chemically bonded to each calcium sulfate unit. In finished gypsum board, the incorporated water content usually ranges around 20%.

This percentage is crucial as it affects the fire resistance, thermal insulation properties, and overall structural integrity of the product. While some variations in water content can occur depending on the manufacturer and specific drywall type, 20% is widely recognized as the standard value for gypsum walls. This knowledge is essential for professionals in the building and construction industry, especially when considering fire safety and material performance in various applications.