Travertine over cement board? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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01-07-2003, 06:57 PM
Hi. I'm installing travertine in a bathroom. I was going to put it on cement board. Is the tile more likely to crack that way? Should I use plywood instead? Any other advice is appreciated!

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John Bridge
01-07-2003, 08:12 PM
Hi Amazing, Welcome. :)

We have lots of advice. Travertine is a very soft stone, and it must have a very strong floor under it. We will need to know about the size and spacing of your floor joists and what type of flooring is above them now. Plywood? How thick? Also, what is the span of the joists? How far do they travel unsupported?

Also, may we have a first name?

01-08-2003, 07:24 PM
Hi. My name is Jen. Thanks for replying. The floor is only 25 square feet. The subfloor is old tongue and groove oak in very good condition. I am laying durarock on top of that. Sound strong enough? Thanks

01-08-2003, 07:35 PM
Welcome Jen,

The other piece of the puzzle is joist size, spacing, and span.

The CBU is the best substrate for tile in this case ( other than an old fashioned mud floor).

Pls let us know these variables and we can assist more


John Bridge
01-08-2003, 07:38 PM
Hi Jen,

I should call in the engineering department here, but for 25 square feet I'm willing to chance a top of the head reply. :D

Give it the "jump test." Takes two people, one to jump and the other to keep his/her hands out of the way while gauging the reverbration on the floor. If it feels like it's bouncing, then it's probably not strong enough for tile. If it feels very solid, it's probably okay.

I know all of this is subjective. If you want the engineers, you'll have to tell us how the floor is constructed. Engineers only understand numbers, not English. :D

01-09-2003, 06:49 AM
Jen, even with a strong joist system, you will need a layer of plywood between the oak flooring and the backerboard. Solid wood planks or strips are not dimensionally stable, you will get expansion and contraction with weather and humidity changes that are greater than the thinset/tile/grout can handle. If you go to the websites of any of the backerboard manufacturers, they will always specify plywood over planks for their product.

Height may be a problem with 3/8" to 1/2" plywood and 1/4" backerboard, then tile. There are ways around that, you could substitute a decoupling membrane called Ditra, for the backerboard. That will save you a little (maybe 1/8")

We are getting ahead of ourselves. Can you get the joist information (size, spacing and unsupported span). I'll run the numbers and we can go from there.

(Hey John, I understand English, a little Spanish, and a whole bunch of hand gestures! :D )

John Bridge
01-09-2003, 07:24 AM
I done got caught.:(

01-09-2003, 09:16 AM
Wow! Great info guys. The construction of the joists and so on is hard to explain. This is an old carriage house/garage converted to a house. The floor I am doing is on the ground level. The joists are massive. I guess they used real wood back then! Anyway, were talkin' 2x6s spaced eight inches. We did the jump test BTW, and there was almost no vibration. Thank god this is my mom's house since it has become a big CF deluxe because of the old plumbing!
There would be a height problem with the toilet and plywood. Can I do something like add a toilet flange extension to raise the height of the toilet? (Without getting too much into plumbing as my skills there are weak).

01-09-2003, 10:06 AM
OK, your floor is a garage/carriage house main floor. It might work.... :D (tile on!)

Yes, they make flange extenders. Go to a real plumbing supply house and ask for a closet flange entension kit. They come in 1/2" and 1/4". You may need both, just stack them.
(plumbing shown is PVC, but will work with any closet flange)

Old plumbing = cast iron?

(I think I know what a "CF deluxe" is. I had one, once! :D )