Flooring Tile - Are backerboard and cementboard the same?

I am doing my front hall in natural stone tile. The subfloor is (2) sheets of 5/8" plywood so I think I'm OK.

I need to lay something between the plywood and my tile. I am thinking of 3/8 backerboard, then thinset, and then the tile.

Is backerboard the same as cementboard? I used 1/2" cementboard when I tiled over my existing fireplace with natural stone tile and it worked great. I am thinking of using the same product fo the floor except for making it 3/8".

Any information or tips/suggestions are very welcome.

Thanks.

Trip

Backerboard is a generic term for the many types of board underlayment available. Cement board is a backerboard, but all backerboards are not cement board. I havent seen 3/8 cement board. Most come in 1/4" and 1/2", but I think the durock is a little thicker than others. 1/4" cement board should be ok, the 1/2" is not needed unless you are looking to add the extra height to the finished floor. The two layers of plywood that you currently have is a good thing for natural stone. There are other issues though. Your floor must meet deflection of L720 for natural stone tile. Thats twice the requirement for ceramic. Natural stone needs a very strong, stiff substrate. Most structures don't meet L720 unless it was known that natural stone would be used. You need to check to make sure your floor structure will support a natural stone installation. You may have to do some work to get the structure up to par.

What is the deflection of L720?

The joists are 2x10 - 16" apart on center. They only run about 6.5' from the foundation to a steel I-Beam so I think they are pretty sturdy and wouldn't have much sag or give being run such a short distance.

"1/4" cement board should be ok, the 1/2" is not needed unless you are looking to add the extra height to the finished floor." - Actually, I am looking to add as little height as possible because of the front door so I would probably go with the 1/4" unless it would compromise the substrate...

Thank you for your response. Please let me know what L720 means.

Tripper

Deflection is a term to describe the degree to which a structural element bends under a load. With an unsupported span of 6.5' your floor is more than adequate for natural stone.

As to cement board, it adds little to no strength to the structure. It is merely there as a good bonding surface for the tile. 1/4" is made to be used on floors, while 1/2" is generally made for walls. You can use the 1/2" on a floor though. There are other options if the 1/4" cement board is going to put you up to high. You can use membranes over the plywood instead like ditra and cis.

http://www.schluter.com/english/products/2002/sectionf/ditra/601-index.html

http://www.noblecompany.com/literature/NobleSeal_CIS_PDsc_0705_lr.pdf

Johhny, It's nice to see someone else explaining about 1/4 versus 1/2. In the area I used to live, there were a number of so called tile setters who didn't understand that and I was constantly getting in discussions with builders over it because the last guy put 1/2 on the floor telling them it was stronger.

I agree. If you can afford more height, plywood which is structural is always the better option. 1/2" cbu as to 1/4" wont do much except add height.

Thanks for the resposes guys! Very appreciated.

Tripper

But 1 thing was left out of the first post in the order of installation. You must set the backer into a bed of thinset before fastenning it to the floor. then thinset, then tile, taping the backer joints as you are setting.

But 1 thing was left out of the first post in the order of installation. You must set the backer into a bed of thinset before fastenning it to the floor. then thinset, then tile, taping the backer joints as you are setting.

Yes maybe even more than one thing. I tend to do that sometimes. Thanks Tilebri. The info provided so far is basic, and not detailed. Once you decide which way your going to go, come back and ask detailed questions. Cement board and membrane manufacturers all have good installation instructions on their websites, and it pays to print them out and read them. Also if something in the instructions is not clear, they have support that you can contact either through email or phone. Also obviously you can come back here and ask as many questions as you want.