rookie mistake??? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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01-29-2003, 07:33 PM
hello first gentle..

total renovation of my bathroom..down to studs..used durock for shower walls and floors, and just found out I may have installed the durock it upside down!!

my question is for installing tumbled marble (4"x4") on durock with modified latex thin set does the textured side of the durock have to be used, or can i leave it the way i have it with the smooth side up and tile away?? please help!!

P.S. I have seen some post regarding the Bonsal shower pan..I am using it for my shower pan and will let everyone know any pros or cons.


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01-29-2003, 07:45 PM
The CBU is the same composition throughout even though one side has a bit more texture than the other.

Although I have not made this "mistake", I see little harm in the use of the "slick" side. You will need to make sure the thinset is troweled into the board to ensure a good bond is formed.

If you really want to be sure, take a piece of scrap tile and thinset it to the "slick" side of some scrap CBU. Check the bond after 4-5hrs . I would expect it to hold quite well.


John Bridge
01-29-2003, 08:16 PM
Hi Birdman, Welcome. :)

It just doesn't matter, as Jason has indicated. Cement sticks to cement. Forget it.

Now, give us a first name, will ya? I don't want to call you Bird. My parrots will get jealous. :D

Sonnie Layne
01-30-2003, 03:02 AM

I don't know why, and it seems counterproductive to me, that all CBU mfg's specify their smooth side toward the tile (outside). Seems to me the inside would allow for more traction/surface area.

I suspect it is highly likely because of the dust that settles on their product while being shipped palletized over long distances and the way it's laid on the pallet. The dust left on the lower surface can settle down into the tiny indentures and possibly allow a release area. I'd say as long as everything is wiped out, or sprayed down to dampen it, you'd end up with a better bond on the rough side. On the other hand, I didn't write the warranty.

I'd say you'll be fine either way. Moistening the substrate never hurts no matter what you're using.

01-30-2003, 04:21 PM
thanks for the help!!

first name dave...i'll keep you posted on the project.

01-30-2003, 04:56 PM
And don't forget pichers Dave, we all like to look at pichers. :D