I'm tiling some rooms that had vinyl tile and carpet over concrete slab. The cutback residue left behind do I have to scrape that off? Vinyle cutback is black and the carpet cutback is clear.

I know Mapei Ultraflex 2 & 3 can be used over cutback but I got off the phone with their technical consultant and he tells me the cutback needs to be grinded off...kind of misleading on their packaging.

So do I really need to grind these rooms down? What do you recommend and whats your experience with this application? Any help would be much appreciated! Thanks

I have installed over cutback with ultraflex 3 numerous times and have yet to have a callback or any problems. Having said that, grinding it off is definitely better.

I've decided to rent the floor grinder for a day and do the job right. It's going to cost me a few hundred bucks more but it's only a fraction of the cost of what I'm paying for material. Do the job right the first time!

Paul

Good move Paolo.

Generally the thin sets that claim to go over cutback will tell you to cut off the adhesive until there is only a film left. Cutback is/was used for asphalt-vinyl asbestos & vinyl composition tiles.

What the heck is carpet cutback? No such thing as far as I know. Cutback is petroleum/tar based. Vinyl and carpet adhesives are rubbery.

Jaz