as 59 with double drywall on both sides of a wood stud wall with resilient channels on one side and glass wool batt insulation between the studs. Sound transmission may be slightly reduced using regular panels (with or without light-gauge resilient metal channels and/or insulation), but it is more effective to use two layers of drywall, sometimes in combination with other factors, or specially designed, sound-resistant drywall. Water damage and mold Drywall is highly vulnerable to moisture due to the inherent properties of the materials that constitute it: gypsum, paper, and organic additives and binders. Gypsum will soften with exposure to moisture and eventually turn into a gooey paste with prolonged immersion, such as during a flood. During such incidents, some, or all, of the drywall in an entire building will need to be removed and replaced. Furthermore, the paper facings and organic additives mixed with the gypsum core are food for mold. The porosity of the board—introduced during manufacturing to reduce the board's weight, lowering construction time and transportation costs—enables water to rapidly reach the core through capillary action, where mold can grow inside. Water that enters a room from overhead may cause ceiling drywall tape to separate from the ceiling as a result of the grooves immediately behind the tape where the drywall pieces meet becoming saturated. The drywall may also soften around the screws holding the drywall in place, and with the aid of gravity, the weight of the water may cause the drywall to sag and eventually collapse, requiring replacement. Drywall's paper facings are edible to termites, which can eat the paper if they infest a wall cavity covered with drywall. This causes the painted surface to crumble to the touch, its paper backing material being eaten. In addition to the necessity of patching the damaged surface and repainting, if enough of the paper has been eaten, the gypsum core can easily crack or crumble without it, and the drywall must be removed and replaced. In many circumstances, especially when the drywall has been exposed to water or moisture for less than 48 hours, professional restoration experts can avoid the cost, inconvenience, and difficulty of removing and replacing the affected drywall. They use rapid drying techniques that eliminate the elements required to support microbial activity while restoring most or all of the drywall. It is for these reasons that greenboard and ideally cement board are used