Laminate Installation Over Saltillo Tile

Q: Our home has an old Saltillo tile floor…between the natural variation in the tile and the grout lines the surface is not terribly flat.
After months of worrying about the hassle involved in tearing up the tile in order to install an engineering hardwood floor, I consulted with an experienced laminate installer who has suggested that a 12mm laminate floor (with appropriate underlayment) would do just fine on this surface without removing the tile. His implication is that an 8mm laminate will not do as well, which really limits our options.
What is your opinion on this? Is it really ok to install a laminate floor over tile? Is the 12mm suggestion a good one? What underlayment would you recommend? Any other relevant advice?
Thanks!
Bob Buddecke
A: Saltillo tile adds a level of difficulty to your project since true Saltillo tile is not uniform in dimensions. With the history behind how these tiles are made, every tile has slight variations in height, and dimensions, though some process recently has made them a bit more uniform.
In this case, it is not so much a matter of having thicker laminate as it is a matter of ensuring your get a good underlayment. With tile of any sort, the common suggestion/practice is to grind down the surface some, to get a flat subfloor. From here you will want to install your moisture barrier, then underlayment and flooring. In your case, a dense underlayment will perform better over the grout grooves and variations in the floor. Dense underlayments, such as cork, will prevent more movement in the floor then cheaper foam underlayments.
Having a thicker laminate will, in theory, give you a higher quality floor which can stand the test of time better, but will not directly account for the differences in the subfloor. Your installer’s suggestion of finding a thicker floor is valid for durability reasons, but not to account for the subfloor. Any floor 10mm + in thickness should be good, although several manufacturers make very good 8.5mm or thicker floors that perform better than some thicker floors.
It is ok to install laminate over tile, assuming you take in certain precautions. Make sure you get the tile surface as flat and level as possible. Also, make sure you use a moisture barrier to be safe.
My suggestion would be to grind down the tile some, similar to grinding down a concrete subfloor to level it out in higher areas. Then look into a good underlayment, I would suggest 6mm cork. From there, find a floor you love and install it.