Installing Cement Backer Board

By Tim Carter
©1993-2008 Tim Carter

Summary: Backer board is a term used to describe a drywall-like product that goes behind ceramic tile. Cement backer board was developed first to replace the cement mud and metal lath systems installed by real craftsmen. Tile backer board now comes in all different types from cement to specialized gypsum-core products that are faced with fiberglass. Installing cement backer board is easy if you have the right tools.

 

DEAR TIM: I have a ceramic-tile job coming up and want to use cement backer board. I have never installed this product before, and wonder if it is really worth it. It seems hard to work with and I am tempted to just use a water-resistant drywall. Is cement backer board really worth the trouble? What tips can you share to make the job go easier and faster? Jackie L., Pleasant Hill, CA

DEAR JACKIE: There are all sorts of different tile backer board products out there. Some are cement-based, some are gypsum-based and others have a mix of ingredients. The cement-backer-board products can be a little tough to work with during the installation process, but in my opinion, they pay you back in spades for the effort.

I am not against new technology when it comes to building products. There are countless examples of where a new product is much better than existing products. Plywood and oriented strand board (OSB) are excellent examples of this. Before plywood and OSB, carpenters used to deal with smaller pieces of wood that were not as dimensionally stable as plywood and OSB. Plywood and OSB also makes very good use of wood as a natural resource.

But when it comes to tile and what it should be applied to, I feel that cement might be the standard to a large degree. Cured cement is not damaged by water. You can immerse a piece of cement board in water for an indefinite amount of time, and it will never fall apart.

This small piece of cement backer board is just 1/4-inch thick. It is perfect, since it is covering solid wood. PHOTO CREDIT: Meghan Carter
This small piece of cement backer board is just 1/4-inch thick. It is perfect, since it is covering solid wood. PHOTO CREDIT: Meghan Carter
There are tens of thousands of ceramic-tile installations all over the world that are hundreds of years old that are still in great shape. Almost all of these are installed directly over concrete or some cement-based material. Many older homes still standing in the USA have ceramic tile firmly attached to cement stucco that was applied over wire mesh by true craftsmen.

All that being said, there are indeed other high-performance backer boards for ceramic tile. This past summer I decided to test a newer one in my daughter's bathroom. It has a rough fiberglass face and a waterproof gypsum core. It was easier to cut than cement backer board, but the installation of the product to the wood studs was the same as far as I was concerned.

If you want a gorgeous ceramic-tile job, you need to be sure the backer board is in the same plane and the walls are perfectly plumb. In the old days, the tile setters installing the wet cement stucco took the time to get the stucco perfectly plumb and flat, even if the wall studs were crooked, bowed or bent.

With modern cement backer board, you must get the framed walls perfectly plumb and flat. Since the cement backer board is thin and a uniform thickness, when you attach it to the studs, it simply conforms to the shape of the stud wall. This means twisted, out-of-plumb frame walls will lead to twisted, out-of-plumb ceramic tile. No one wants that.

The cement backer board can be cut with a circular saw with an abrasive blade, but that process creates clouds of choking dust, and can cause great damage to the saw motor. You can score the cement backer board with a hand tool that has a carbide tip. You make numerous passes along the cut line, and then apply pressure to the other side of the cement backer board along the scored line. It usually snaps the backer board in two quite nicely along the desired line.

I also recommend a water-resistant barrier between the backer board and the wall framing. You can put overlapping layers of asphalt felt paper or go with a large sheet of plastic commonly used for a vapor barrier. This layer helps protect the wood framing from wood rot in that rare case where water would soak through the cement backer board.

When installing the cement backer board, I like to leave a 1/8-inch gap between pieces. This gap is then filled with pure silicone caulk before the ceramic tile is installed. I never allow the cement board to rest on top of a bathtub edge. If water gets to the cement board, capillary attraction can cause water to wick up into the cement backer board. I always leave a 1/4-inch gap between the top of the tub and the bottom edge of the backer board.

The cement backer board can be screwed or nailed to the wood framing. Always follow the instructions printed by the manufacturer. I use hot-dipped ring-shanked nails if I am nailing. Corrosion-resistant screws can also be used. You need to make sure the cement backer board will never fall off the wall at a later date. Inferior fasteners can cause catastrophic failure if they rust.



 


Comments:

B. J. James
23 Nov 2007, 13:45
Question:

On one whole wall of our den, there is a brick fireplace/wall. (This is an outside wall.) Over a period of years, the brick has become covered with a white, grainy, substance that flakes off and is ruining the mantle and any pictures or items on the wall. (we have a couple of mounted deer heads and a nice mounted fish hanging on the brick.) The mineral substance is ruining the wooden plaques that they are mounted on.)

We would like to cover the brick with something like sheetrock, but the moisture would seep through, and also, it would not be fireproof. I am wondering if there is a way we could use cement board to cover the brick, and if it would be moisture and fire proof. Can you please advise me?
Chris Apmann
08 Dec 2007, 00:06
Actually, I have two questions that I really hope I can get assistance with. The first question is this, I am trying to level a concrete living room floor that drops a little over 1" in seven feet in one corner.

Has anyone ever used the self-leveling concrete, and how self-leveling is it? Is there much prep or post leveling work involved?

The second question is this, I have a plaster popcorn ceiling (circa 1975) with radiant heating coils in the ceiling. The coils do not work; and I want to get rid of the popcorn ceiling which might have asbestos and install recessed lighting. There is no attic. I live in a third floor condo unit.

What is the best way to get rid of the popcorn, and how?

Thank you for any assistance you can provide.

Chris Apmann
AsktheBuilder
08 Dec 2007, 07:05
Chris,
You can buy excellent self-leveling compounds. USG has a new one I am dying to try on a job. Spray a small area of the ceiling with water. Mist it for several minutes. Use a flexible putty knife to scrape off the popcorn. If it was never painted, it will come off easily. Keep it wet to minimize any hazard from asbestos *if* it is present. To be 100% safe, take a sample of the popcorn and have it tested. It is easy to find one online.
Bob Marks
10 Dec 2007, 19:33
Hi Tim,
I need to get the stain and crud off of my shower pan. It has the non-slip floor and I have tried various cleaners in the dimpled non-slip area with out results.
Thanks,
Bob Marks
AsktheBuilder
11 Dec 2007, 08:20
Bob,
Please read *all* of my past columns about cleaning ceramic tile. You will discover a chemical in your kitchen pantry that will solve this pesky problem.
Bob
16 Dec 2007, 19:20
Due to the drain location in my basement cement floor, I am considering pouring a shower base consisting of concrete and tapering it toward the drain. In doing so, I can get the maximum size of my shower. Can I do this without water leaking through? or potential long term water problems between the floor and the base? How thick should the concrete shower base be? I was considering framing the shower and installing backerboard. ONce framed, I was going to pour cement approx 3 inches thick. Will this work?
AsktheBuilder
16 Dec 2007, 21:27
Bob,
This will be a dismal failure. You need to read all of my past columns about Shower Pan Liners.
Bob Tanner
23 Dec 2007, 08:58
greetings,
My question for the craftsman is, can I lay hardy-backer board directly over linolieum as long as it is properly secured with backer board screws? Its regarding a bathroom floor that im going to tile. The house has a plywood sub-floor,est.1988, and the linolieum is smooth and flat. I hope this is enough info, I just want to do it right the first time so I thought I'd ask the builder!

thank-you for you time- sincerly,
Bob Tanner
AsktheBuilder
23 Dec 2007, 10:14
Bob,
If there is no cushion under the sheet vinyl, then I say it is fine. But if you can depress the vinyl with your finger, then it must come up.
BOB BULAK
02 Jan 2008, 15:21
TIM;

IS IT NECESSARY TO INSTALL GREENBOARD BEHIND THE BACKERBOARD?

THANK YOU

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