Ardex GS4 SLC over 1/4" Hardibacker? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-26-2008, 08:37 AM
With the help of this forum I redid my downstairs bath and now the work on upstairs begins...

I thought I had it all figured out. I pass the deflecto no problem and I was planning on Warmingly Yours Heating mat over plywood, Ardex P51 primer, Ardex GS4 (2 bags for 40 sq. ft), P51 primer, thinset, ditra, thinset, porcelain tile (mix of 12x12 and 6x6). The beauty of the GS4 is that you dont need lath. This was confirmed by the people at Ardex.

I started the demo this weekend and ran into a snag. Isnt that always the case? The previous floor covering was 12x12 self adhesive (I think) tile. I got the tile up not problem, but there is clear (but sticky) adhesive residue almost gummy in cosnsitency on the plywood subfloor. It blinds sandpaper even coarse grit in a matter of seconds, and even if I scrape (which I did) it still leaves a residue that is hard to remove. I then got REALLY nervous about the SLC bonding to the subfloor and figured it could be a disaster. I thought about laying 1/4" hardibacker over the plywood subfloor. I other than changing the final floor elevation 1/4" this would work. My floor would then be: plywood, 1/4" Hardibacker, P51 Primer, WY Heating Mat, P51 Primer, Ardex GS4 SLC, P51 Primer, thinset, Ditra, thinset, tile.

What do you guys think about this approach?

Is there any issue with the grid pattern and the SLC since the 1/4" Hardibacker has the grid pattern on it?

Thanks for your help as always

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