Cement board
![Cement board is composed of aggregated Portland cement with a glass-fiber mesh on the surfaces. This 5/16 inch (7.9 mm) thick cement board is designed as an underlayment for tile floors. These are 3 by 5 foot (91 by 152 cm) sheets](/Images/godic/202501/03/Cement_Board2416.jpg")
A cement board is a combination of cement and reinforcing fibers formed into 4 foot by 8 foot sheets (or 3 foot by 5 foot sheets), 1/4 to 1/2 inch thick that are typically used as a tile backing board. Cement board can be nailed or screwed to wood or steel studs to create a substrate for vertical tile and attached horizontally to plywood for tile floors, kitchen counters and backsplashes. It can be used on the exterior of buildings as a base for exterior plaster (stucco) systems and sometimes as the finish system itself.