Replies

1. 
   Sancho | Jan 22, 2004 06:43pm | #1

   No but there is a thin set made for concrete. and if you have cracks in the concrete you'll have too deal with them.

    

   Darkworksite4:

   Estamos ganando detrás el estado de Calif. Derrotando a un #### a la vez. DESEA VIVO LA REVOLUCIÓN

2. 
   origamiboy | Jan 22, 2004 08:49pm | #2

     no, but you will want to use a crack isolation membrane for sure. Cheap insurance.

3. 
   Scooter1 | Jan 22, 2004 08:57pm | #3

   No.

   Do a water test. First, dump some distilled imported French free range water on the concrete and see if it absorbes. If it does, you are good to go. The thinset will bond. If not, you may have to scarify the surface or apply a membrane for thinset to bond. Second, apply a 10 mil poly sheet to the floor overnight (not the same place you poured the imported French distilled water) and see if there are any ground water issues. If the sheet is not covered with moisture beads the next day, you are good to go.

   Assuming you are good to go, you have two ways to lay the tile, with or without a membrane.

   1. No Membrane. If your ground and slab is stable and crack free (read: not in California or Iran), you may be able to get away without a membrane and save $5 a square foot. Apply a thin slurry of regular thinset, like Custom's Versabond at $15, into the concrete slab and let it sit about 5-10 minutes to soak in. Then go back with a knotched trowel and set your tile. I know of no special concrete thinset, but there might be one.

   2. Membrane. If your slab has issues with bonding (see 1st paragraph) or has cracks, or you want some extra insurance, lay down a membrane like NobelCS, Ditra, or a PVC membrane and tile over that. You can also apply a liquid brush on membrane with a fiberglass mat, like Laticrete Blue 92 and then tile over that.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

1. 
   brownbagg | Jan 23, 2004 01:32am | #4

   if the concrete is new, make sure there no moisture wicking from the concrete. Tile does not like moisture

   nuthing but happy thought.

1. 
   Scooter1 | Jan 23, 2004 02:11am | #5

   Thats why I said do the poly test.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

1. 
   Sancho | Jan 23, 2004 02:47am | #6

   I was reading in 'The Tile Letter" that they are now making a thin set to go over concrete so the moisture wont bother it. I have not used it but that is what they said. 

   Darkworksite4:

   Estamos ganando detrás el estado de Calif. Derrotando a un #### a la vez. DESEA VIVO LA REVOLUCIÓN

1. 
   Scooter1 | Jan 23, 2004 03:51am | #7

   OK, that news to me. I haven't seen it the masonry stores, and have been using Versabond for concrete at $15 a bag for years. I won't change, thats for sure.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

2. 
   Sancho | Jan 23, 2004 06:56am | #9

   Yea I use Versa bond also great stuff. I found out about the moisture resistant stuff about 2 weeks or so ago. I havent used it but maybe Ill ask what the guys at John Bridge think about it. 

   Darkworksite4:

   Estamos ganando detrás el estado de Calif. Derrotando a un #### a la vez. DESEA VIVO LA REVOLUCIÓN

4. 
   Dinosaur | Jan 23, 2004 05:37am | #8

   I've had success using Lepage's Professional tile adhesive directly on the concrete. 2x2 mosaic tile. The concrete was two years old; no ground water issues; no glaze coat on the concrete floor. If your conditions are similar, this is a lot easier and probably less expensive than thinset and membranes.

   Dinosaur

   'Y-a-tu de la justice dans ce maudit monde?