SLC or not? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-28-2008, 12:56 PM
I have a room about 8x19 on a concrete slab. The slab has some dimples in the surface, and a sectioon patched after plumbing was installed. I plan on putting down some 12x12 ceramic tile over an embedded electric radiant heat mat (ThermoTile from thermosoft).

The concrete is fairly level and perhaps 1/8" out of flat (where the dimples and patch job were done).

I'm wondering if I should just put down the mat, and use thinset or if I should put down the mat, pour some SLC to flatten it perfectly and then install the tile.

SLC seems a bit of a PITA, and I'd prefer to simply use thinset to make up for the defects in the slab ...

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02-28-2008, 05:29 PM
Hey there!

The folks around here are pretty casual and it's kinda cool to use your first name (or a nick if that's better for you) when you post a message. That said, Welcome to the Forum!!!

About your question, You can go either way, just make sure you use the right materials and methods. There are a few concerns that you need to deal with;

1) Condition of the slab...cracks? clean? moisture? stability?

2) Adhesion of the mat and tiles using only thinset

3) Protection of the mats when doing all the work

#3 is my favorite, I'm an electrician so I kinda want those mats to survive a long time. From experience, the sooner the mats get covered the better, so SLC really helps a lot!

- pete

02-28-2008, 05:46 PM
I personally feel the key for a neophyte to getting a good slc pour is not to try to do a minimum depth pour. It can be done on concrete (a wood subfloor requires it to be thicker - most manufacturer's recommend 1/2" over the highest point for a wood floor), but if it doesn't have some depth, it's hard to get everything 'wet' with the stuff and high enough to flow and level. Think pancake doesn't taper to an edge, it sort of beads up in the pan. SLC does that a little, too. If you can get it spread out, it's more like a crepe. Tiling over a nice flat floor is a boon, and easier to to achieve with slc than thinset.

But, 1/8" is not much. You could fill those dimples first using thinset, then install the heating.