If I did do the membrane seal then I could still get moisture wicking up the backerboard from the mud pan, which would then be behind the vapor barrier. Layout the cement backer board at right angles to the plywood subfloor so the joints in the backer board are staggered and donât fall on joints in the plywood. The Strength of Portland Cement Installing cement board at the beginning of your remodeling project is crucial when you want waterproof tile floors that will last for many years without cracking or other signs of damage. It can be used to cover nearly any surface, including floors, back splashes and countertops. In this highly convenient, inexpensive, and popular application, a moisture barrier of 4- or 6-mil-thick plastic is installed directly over the wall studs. it's O.K. However, excessive water damage such as a broken pipe that leaks for weeks or months can eventually break down the concrete board's particles, leaving behind a crumbly mess that was once solid board. USG Durock ® cement board is an outstanding backerboard for a wide variety of reasons. Cement Board and Plastic Sheeting . The standard size sheet is 3 x 5 ft. and 1/2 in. HardieBacker board is not designed for use over concrete. The 1/2-in. Ok, gotcha. *** Fiber cement board is almost the perfect exterior siding. Unmodified thinset (ANSI 118.1) or acrylic modified thinset (ANSI 118.4) is specified between the HardieBacker board and the subfloor to eliminate any deviations between our product and the subfloor. Screws secure the cement board to the wall studs. Here are 10 ideas to try yourself. Follow answered Aug 20 '17 at 2:15. joe joe. 06-02-2008, 03:51 PM. thick cement board ⦠A fiber cement boardâs qualities as an exterior siding make it good for interior applications, too. That is the up and down movement in your floor when you walk, jump, or use a pogo stick on your floor. I'm building a custom shower and I'm confused about the best method of backer board installation. and is available at most full-service lumberyards and building supply centers. You need to realize that cement backerboards, or just about any tile flooring substrate, does not add deflection stability to your floor. was just making sure. Improve this answer. thick, weighs 45 to 60 lbs. Share. Made of wood pulp and cement, it is durable, low maintenance, and resistant to fire, bugs, rodents, mold, and moisture. Cement boards are generally unharmed by minimal water damage, such as underneath a toilet where water eventually seeps out over the years. 1/2 inch cement backer board on top of the thinset and screwed in just after the thinset is applied. Another problem is that mold grows in drywall, so if moisture is passing through the cement board into the drywall, it's creating ideal conditions for a mold colony, which will hasten deterioration of the wall studs and create a giant headache in a few years. It may sound like a daunting task, but learning how to install cement board on a floor is possible even if you donât have years of DIY experience. Then, the cement board is installed on top of the plastic sheeting. northman. Cement board, technically called cementitious backer unit (CBU), is manufactured under different brand names. to walk on the cement board before the thinset sets. Choose this high-performance alternative to fiber-cement boards or bare plywood surfaces for: Superior Tile Bond Prevents tile pops and grout cracks, up to 40% greater tile bond than fiber-cement board. I've heard you should install backer board about 1/4 inch above the pan, with backer rod or some type of sealer to prevent wicking up into the board. Cement backer boards, on the other hand, do not have this issue, which is why they are used instead of drywall. ... using cement board with a vapor barrier behind it. Cement backer board is used to create a smooth, strong surface for laying tile. Why do I have to use thinset between HardieBacker® cement board and the subfloor? Leave a 1/4â³ gap between the backer board and walls and 1/16â gap between the sheets of backer board. The backerboards will not significantly diminish that movement.