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.
Norm Abram replies: The 5/8-inch, fire-code drywall (called Type X) increases a wall's fire rating to a minimum of 1 hour, from the 30-minute rating for standard Â½-inch drywall. And it's not just thickness that makes the difference. Type X has a denser core and contains glass fibers that keep it from crumbling in the heat.