Both gypsum plaster and gypsum drywall board provided fire resistance to the building, due to the chemical composition of gypsum. … This means that it is calcium sulfate (plaster of paris) combined at the molecular level with water of crystallization.

Is plaster more fire resistant?

Plaster is more fire resistant than drywall. While plaster walls are smooth and flat, they contain slight surface trowel marks, adding a desirable Old World feel to the character of a home.

Is lath and plaster fire resistant?

Lath and plaster ceilings have a major role in preventing fire spread. … The longer the ceiling remains in place, the greater will be the fire separation between floor levels. Published data on the fire resistance of lath and plaster ceilings is limited.