concurrent causation. (1) A tort doctrine that imposes joint liability on two or more parties if their negligence combines to produce the same loss. (2) In property insurance, this term refers to a situation where there is a mixture of covered and uncovered perils acting together (either in sequence or simultaneously) to produce the same property damage.
Drywall is relatively fireproof, but manufacturing processes such as adding glass fibers can increase the resistance. Drywall is relatively fire resistant. It's composed of gypsum pressed between two sheets of thick paper. Gypsum is a soft mineral that by itself is not flammable. Additionally, water is incorporated into its structure. In the presence of fire, heat energy vaporizes the water, removing it gradually. Water effectively blocks the transfer of heat through the drywall.
The plaster is mixed with fibre (typically paper and/or fibreglass), plasticizer, foaming agent, and various additives that can decrease mildew, increase fire resistance, and lower water absorption. Drywall construction became prevalent in North America as a speedier alternative to traditional lath and plaster.