Quarry tile problem

[Brian Clough]

I laid self-levelling-compound over quarry tiles last year (1927 house), everything looked good and sound so proceded to cover that with hardboard and vinyl flooring.
After 6 months the SLC started to lift. I've now taken it all up - very easily.
Two possible problems, either no DPM or I should have PVA'd the quarry tiles first. I suspect that if the lack of a DPM is the problem then PVA (being water soluble) would not have helped.

I have had suggested to me a bitumen coating (several coats) onto the tiles.
I have also seen suggestions that I should "blind" the top coating to give the SLC a better adhesion.
All help welcomed, and referals to specific materials would be great.

 

[mattysupra]

have a look at the f-ball website. Use dpm prep compound with epoxy dpm if moisture problem. If not use acrlic compound with 131 primer.

 

[Brian Clough]

f-ball website looked encouraging, but went into my local vinyl flooring supplier (not a retail park merchant) who contacted F Ball Technical Dept with the problem. Short answer - they could not recommend any of their products for my application. They recommend - dig up the floor and replace with modern DPM and screed. Prefer not to do this as it would mean completely re doing my kitchen for the sake of 3m² of quarry tiles.
Any further thoughts?

 

[mattysupra]

That is because to british standards you should dig up floor as they said. They will tell you that you cant use there products over a floor that has a moister content of more than 75% rh (british standard), they have to follow the british standard. And you should as well. But as another method to fix ( not to british standard so no guarantee ) You can do as i said before. Acrylic smoothing compound and then dpm epoxy. Or you can use f-ball isolator membrane ( sheet material that floats over old floor, but still allows to breathe ) Or you could put down vapour barrier and then fit a floating system http://www.soundseal.com/impacta/jumpax.shtml
But again you shouldn't really be installing any of these products on a damp floor.

 

[Brian Clough]

Thanks for your help.
There is no sign of dampness; have lived in the house for 25 years, no discolouration of the quarry tiles.
As part of taking up our old vinyl flooring it lifted a couple of the earlier fitted thermoplastic tiles (so had to lift the lot) - the tile adhesive was black. I assume that this might have been bitumen based, the thermoplastic tiles were soundly secured to the quarry tiles. I assume that the black adhesive (bitumen?) was acting as waterproofing barrier.
Will follow up your latest advice.
Travis Perkins have suggested Laybond Aquamac Aquaprufe (3 coats) onto the quarry tiles, and then Cempolay SLC.

 

[mattysupra]

I have never used that product so dont know how good it is. But if you have no damp, just prime with 131 primer and then acrylic compound. You should remove as much of the bitumin glue as possible before you lay tho.