Fireproofing Gypsum Plaster

When used as a component in fire barriers, gypsum plaster is a passive fire protection item. In its natural state, gypsum contains the water of crystallization bound in the form of hydrates. When exposed to heat or fire, this water is vaporised, over a range of temperatures from 80° to 170 °C, retarding heat transfer until the water in the gypsum is gone. This makes gypsum plaster an ablative… More

When used as a component in fire barriers, gypsum plaster is a passive fire protection item. In its natural state, gypsum contains the water of crystallization bound in the form of hydrates. When exposed to heat or fire, this water is vaporised, over a range of temperatures from 80° to 170 °C, retarding heat transfer until the water in the gypsum is gone. This makes gypsum plaster an ablative material because as the hydrates sublime, a crumbly dust is left behind, which, along with the paper, is sacrificial. Generally, the more layers one adds, the more one increases the fire-resistance of the assembly, up to four hours for walls and three hours for ceilings. Less