Ditra mat over vinyl over concrete?

10 years ago

Hello all, we are working on a kitchen renovation and installing new porcelain tiles. We had removed the floating laminate floor (a typical click lock style) and underlayment to find two layers of vinyl floor underneath. The first layer of vinyl is coming up relatively easily with a scraper (bottom of the pic) but the second layer (main part of pic) is really solidly adhered to the concrete slab with a rock hard white substance (top left) which is likely glue but looks a lot like white thinset. The house was built in approximately 1960 and I'm betting the bottom layer of vinyl is original. It is barely coming up in small crumbles (like the pattern) when I attack it with the scraper so am looking at other options. Thinking about Ditra mat, which I have used on a wood subfloor and a concrete subfloor before, but never on vinyl. Any experiences with that? It looks like the Ditra handbook says it is possible, using a latex modified mortar first, then the Ditra, then unmodified.

Thanks for any advice!

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Comments (6)

weedyacres
10 years ago
I'd definitely consult the Ditra instruction booklet for "permission." But first you might try a steamer on the vinyl to loosen up the adhesive. It worked for me, albeit over wood, not concrete.
glennsfc
10 years ago
Wet the backing or steam it as you work. The backing contains mineral fiber asbestos. Don't sand it off. Wet it, slice it, place it in bags for disposal.

Consult with Schluter, as you probably can leave the vinyl down.
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StoneTech
10 years ago
Ask Schluter, but I think the vinyl should go. The surface is waterproof and the Ditra is waterproof. Thinsetting the two together will take forever for the morter to set up or hydrate.
MiaOKC
Original Author
10 years ago
I do think the vinyl and paper backing has to go. I don't want to save a little now but pay for it with a complete tile failure in the future.

I think we may rent a floor scraper from HD just to get all the way down to the concrete and then we can start from scratch. I might skip the Ditra, though, since I will be bonding to a clean surface.
User
10 years ago
You will need some sort of isolation membrane, whether Ditra or something else. Otherwise you will be asking for problems - any minute crack will telescope up through your tile.
StoneTech
10 years ago
I agree. Prep the floor and then either Ditra or Greenskin...