12mm RCM Cemboard Cement Bonded Particle Building Board is a rigid, medium density, high-performance cement bonded particle building board which offers great strength and stability with the workability of wood. 12mm RCM Cemboard Cement Bonded Particle Building Board is used primarily as an external sheathing board. It provides excellent acoustic properties making it an excellent acoustic building board. Used extensively on both metal and timber frame structures, it is also a great choice for modular and offsite builds.