I am laying slate (8mm calibrated) onto a concrete floor that is covered with hard plastic tiles (seems they were very popular in the 80s in newly built houses). The tiles are very well fixed and sound.

I have bought BAL single part flexible, but do I need to change it for the rapid setting version due to using slate? Are there any benefits (apart from a faster job?)

I guess that the back of the slates should also be buttered with adhesive.

I have already gathered from these forums to treat the slate with Lithofin MN Slate Seal before I lay it!!

Thanks

Is this a DIY or Pro job?

And... how fixed are those 'plastic' tiles? I'd be a bit sceptical as to how secure those are, as your slate is only going to be fixed as fixed as those are, and I bet they've only been glued somewhat.

You shouldn't need to butter the slate to get good coverage, and you shouldn't have problems with translucency (is that even a word?! ) so using a decent 'thick-bed' trowel with the right adhesive (I'll leave that one to the pro's on here) you should be okay.

Though the adhesive I'm unsure on personally if it's sticking to those existing tiles.

Thanks Dan

DIY, with a fair bit of tiling experience, but not with slate before.

Advisors in a couple of trade suppliers have said that BAL flexible is fine for sticking to those Marley tiles, but for sure I need to verify that they are really stuck down well. But lifting them is bound to leave a lot of bitumin type adhesive behind, which could be worse!

It's just that I read that some natural stone needs rapid set adhesive.

I'll leave it for the Pro's then mate as it's not an area I'd feel comfortable advising to be honest.

Your original choice of adhesive is fine.....but there are cheaper options that perform just as good...

IF the vinyl tiles are well and truly stuck( your decision) then you can tile over...

You need to degrease them with sugar soap then prime with an sbr type primer and tile within 24hrs of priming...

Personally i prefer to remove them and use latex leveller to smooth the floor..