Cement Board - Water Resistance

Water Resistance

The category of construction material known as cement board includes both water resistant and waterproof board. Each has its own best use.

Typically water resistant cement board is composed of a treated gypsum core with a non organic fiber reinforced covering, either on one or both faces. This type of board requires fastidious sealing of all cut edges and penetrations to maintain the manufacturer's warranty for wet area installations. Gypsum core "cement" board panels are ideal for moist but not truly wet installations of tile and/or stone walls.

There is a class of cement board strictly constructed of a Portland cement based core with glass fiber matt reinforcing at both faces. This type board is truly waterproof. These panels can be immersed in water without any degradation (excluding freeze thaw cycles). These panels do not require the sealing of edges and penetrations to maintain their structural integrity. These Portland cement based products are smaller in size compared with the gypsum core based products. Typically they range in size from 30" x 48" to 36" x 60". They are, as one would expect, considerably heavier than the gypsum core type panels.

Portland cement based panels are ideal for truly wet locations like shower surrounds and for locations where a Portland cement based thin-set material is used for bonding tile and stone surfaces to a substrate. They are also ideal for floor tile and stone installations over a structural subfloor.