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.
It depends on the quality of the rayon. Some lower quality rayons wrinkle badly and all rayon is highly flammable unless treated with flame retardant, so be sure to check that since you are thinking ahead to children. I prefer a cotton blend or wool blend, but have never had the poly/rayon blend myself.