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.
As a home inspector, the important thing to know is most typical wall and ceiling assemblies (including tile and stone finishes set on conventional wood-framed walls) are considered combustible. Drywall is also considered a combustible material because of the paper facing. Most fuel-burning appliances come with listed clearances to combustible materials stamped onto the unit. In these instances, it is easy to determine the required clearance to combustible assemblies, then to measure the actual distance.