Melt-Away Ceiling Tiles are used when the sprinkler heads of a fire sprinkler system are located above the finished ceiling. Standard ceiling tiles and drywall are manufacture to resist the heat rom a fire for a period of time. For this reason they cannot be used when the sprinkler heads are above the ceiling. Melt-away ceiling tiles made of nominal 1 lb density expanded polystyrene will start to melt as soon as flames touch the surface. By doing this they allow the heat from the fire to rise above the ceiling to set off the sprinkler system, extinguishing the fire as quickly as possible. Typically used in offices constructed in warehouses and other large industrial buildings, they are available in both flat and tegular design for 2x2 and 2x4 grid systems.