Porcelain title over Kerdi

[LJN55]

I am working on a steam shower. I will be using 8X8 porcelain tile. I know that Kerdi recommends that we use unmodified thinset. However, what would you use to hold the tiles on the ceiling? Mastic is what I have used on ceilings before, because of the stickiness of the product.

Any suggestions?

[Lazarus]

Forget the mastic. It will NEVER fully cure and PARTICULARLY in a steam environment, you're gonna get tiles falling down on your head.

"What would you use?" UNMODIFIED thinset over the Kerdi. Why do you doubt the pros?

[jadnashua]

You certainly don't want mastic in a steam shower!

One technique is to make a ring of thinset around the outer edge of the tile. Then, press it up onto the ceiling. That ring acts like a suction cup and will hold the tile up if you do it right and once the thinset cures, will hold it forever. Since you're not going to be walking on the ceiling, not having 100% coverage isn't a big deal.

[TileArt1]

Hi Lyle,

I have two suggestions:

Unmodified works just fine, in my opinion. Just don't get the cheap $5.00/bag garbage.

Stop using mastic especially in a steam shower -BIG no no. Tiles will fall off the ceiling if you use mastic.

[rjnebbo]

You'll could end up Spastic if you use Mastic, even worse, using on a ceiling could led to a early Casket.

Use what is recommended from the manufacturer

[ceramictec]

hey Lyle,

for your situation I would recommend and ultralight thinset.

like Laticrete 255 multimax or Tec 3n1 or Mapei Ultralite.

a good unmodified like Ditraset would work or even a Versabond, but for the porcelain and the ceiling I like the the better thinset's

[Rkeister]

I would strongly suggest 3N1 as brian stated, my concern is that it's not going to be backed by schluter being latex modified. However, with TEC you can't win over ditra because TEC specifically specifies to use their superflex over ditra & kerdi. I had a contractor use 3N1 over kerdi and it took days to dry.