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.
Not all gases are flammable. eg carbon dioxide, nitrogen or helium. Flammable gases are those which react easily with oxygen in the air to cause combustion... such as hydrogen, methane or propane etc. Even flammable liquids are flammable only because they give off a flammable gas at temperatures below. Gasoline evaporates at room temperature into a mixture of flammable gases which are far more flammable than the liquid itself.