I had this article in my files...it is courtesy of John Bridge.
• Ceramic Tile Floors
- John P. Bridge ( May, 2005 )
“Ceramic tile floors. Sounds simple, doesn’t it? Pull up the rug and “put down” tiles. Smear grout in the joints, clean it up and move back in. If you have vinyl on the floor you can go right over it with the new tiles, as vinyl makes a wonderful uncoupling membrane. Tile mastic works better for tile floors than thin set mortar does, especially when using large tiles. If the floor structure seems a little spongy, you can correct it by nailing down cement backer board before installing the tiles themselves.”
You have just been presented with a paragraph-size synopsis of the type of tile
misinformation you might receive on the Internet, in tile and flooring outlets, at big box stores and in certain printed publications, not to mention home improvement shows on radio and TV. Yes, there are thousands of “experts” out there poised and eager to set you straight and get you on your way to tile flooring bliss. Don’t buy into it for a minute.
In the next few paragraphs I intend to give you a very brief overview of the correct ways that ceramic tile flooring should be installed. I’ll list sources of further reading at the end.
First of all, ceramic tiles (to include porcelain tiles, quarry tiles, various paver tiles and others) are hard, brittle and breakable. For them to be installed successfully on floors they must be well bonded and well supported underneath. If your floor is the least bit springy or “mushy” when you walk on it, it will be necessary to do some serious shoring up before tile setting begins. I cannot over-emphasize this. For our purposes, the tiles themselves have no structural value of their own. The use of cement backer boards or various membranes will not ameliorate an unsound floor structure.
• Cement Backer Boards
Cement backer boards, such as
PermaBase,
Wonder Board,
Durock,
Hardi-backer, and others are used to “uncouple” a tile installation from the subfloor below. Before they are fastened, CBUs, as they are called, are bedded in thin set mortar, which is the usual adhesive used in setting floor tiles. The panels are then nailed or screwed to the subfloor following manufacturers’ specific directions. CBUs do NOT improve the stiffness or structural value of the floor.
• Anti-fracture Membranes
There are various membranes on the market that accomplish the same uncoupling effect that CBUs provide. Two of the biggest names are
Nobleseal and
Ditra. I happen to be in cahoots with
Schluter Systems, makers of Ditra, and I consider it among the best products on the market. But membranes will NOT rectify an insufficient floor structure. Vinyl linoleum and tar paper certainly won’t do it either.
• Adhesives
“Thin set mortar” is a portland cement product that is used to adhere ceramic and stone tiles to a “substrate.” The substrate is the layer directly under the tiles, i.e., cement backer board, Ditra membrane, etc. Thin set comes in a powder form that must be mixed with water just prior to use. Thin set cannot be pre-mixed before it is needed. It will “set-up” and become hard just like any other cement product. It does not need air to do this, and you can’t keep thin set in a can or plastic tub on a store shelf.
Therefore, any product you see on the shelf purported to be “pre-mixed thin set” is not thin set and cannot be used to install floor tiles. It is instead some sort of mastic, which is an organic glue that might be used to install certain very small tiles on a kitchen back splash, for instance. The same goes for “pre-mixed grout.” Real tile grout is made from portland cement also, and in my opinion, pre-mixed grout should not be used for anything at all.
Remember that thin sets and grouts will ALWAYS come dry in a sack or box, and remember that it is impossible to pre-mix them and keep them from setting up hard as a rock.
Tile mastic, the organic glue, can be used only on small tiles and in areas that don’t get wet. It should not be used on stone tiles at all as it can be absorbed into the stone where it can cause stains. And tile mastic should not be used for ceramic tile floors.
