What is Cement Backer Board?To understand cement backer board, you should first look at a distant cousin--drywall. For years, interior walls were finished with lath (wood strips) and plaster laid over the studs. Plasterers had to use hundreds of pounds of plaster, trowel by trowel.
Then someone got the brilliant idea of pressing all of that plaster, plus the structural qualities of the lath, ahead of time in a factory--in the form of sheets of drywall. Get it? Dry wall. Drywall.
This is the basic idea behind cement backer board. Instead of laying beds of mortar on the jobsite, or using inferior backing boards such as greenboard, you can simply screw in these pre-formed and already-set sheets of concrete board. Pretty neat.
Applications for Cement Backer Board?The great value of cement board is does not rot, warp, grow mold, or deteriorate, when subjected to water. Wood obviously is not a great material to use in wet applications, and even green board, a more hardy type of drywall, is not recommended for places with constant water usage, such as showers. Cement backer board is mainly used as a sub-surface for tiling.
Who Makes Cement Backer Board?There are three main cement board products available to the general home renovator:
- Durock Brand Cement Board, made by USG.
- HardieBacker, made by James Hardie Industries.
- WonderBoard and EasyBoard, made by Custom Building Products.
How to Install Cement Backer BoardIf you have any obstructions to work around, before laying down the boards you can easily (but messily) cut the cement board with a SkilSaw with a carbide blade.
First, you apply thinset mortar on the surface, and "comb" it out with your trowel. Keep the cement boards about 1/4" apart.
After pressing the boards into the mortar, screw them in with screws made especially for cement board installation. Just as you would with drywall, make sure the screwheads are slightly depressed below the cement board surface. Cover and mortar the seams with fiberglass seam tape. Please see our complete cement backer board installation guide.