Understanding Fire Resistant Sheetrock Sheetrock is the building material used to make walls and ceilings in almost all new construction; it is the material that replaced the old lath and plaster technique which lost favor due to the relative cost savings of sheetrock. Sheetrock is a made from gypsum – a mineral mined from the earth. The gypsum is a chalky white substance that can be pressed into sheets and then wrapped in a paper face to make wall boards....