1/4'' x 3/8'' square notch: this trowel size is good for 8'' x 8'' tiles, some builder-grade tiles, and bigger subway tiles (around 4'' x 12''). 1/4'' x 1/2'' square notch: this trowel size is good for installing 12'' x 12'' and 13'' x 13'' tiles.
Depends on the surface of the back of the tile. If it's smooth, then all you'll need is a 3/16th V-notch. If it has deep groves or patterns, then you might want to use a 1/4".
The standard guidelines break it down this way: A 3/16-inch to 1/4-inch V-notch trowel works best for up to 4.5-inch mosaic or wall tile. A 1/4-inch by 1/4-inch Square-notch trowel should be used for 4-inch to 8-inch tile. A 1/4-inch by 3/8-inch Square or U-notch works for 8-inch to 16-inch tile.
DTA square notched trowels are selected depending on the size of the tile to be laid. Use 1.5mm or 2mm for walls and 3-5mm for floors. When measuring out a wall or floor always remember to allow for the width of spacers. DTA recommends removing spacers after adhesive has dried.
Here is a standard Guideline to help you make the right choice for a trowel based on tile size: 3/16″ to 1/4″ V-notch: Mosaics tiles up to 4-1/2″ glazed wall tile. 1/4″ x 1/4″ U or Square notch: 4″ to 8″ tile. 1/4″ x 3/8″ U or Square notch: 8″ to 16″ tiles.
To back butter means spreading the bond coat to the back side of the ceramic, glass, stone or specialty tile prior to placing it into the substrate. Flat backed troweling and notched back troweling are both terms used in lieu of back buttering to further define the process.
Although not necessary for tile coverage, back buttering can be effective by increasing the bond of the mortar to the back of the tile which is an excellent benefit.
Speaking of trowels, the proper notch size matters. Choosing too small of a notch size for larger tile will result in less than 80% mortar coverage on your tile. For instance, a 1/4” x 3/8” trowel would suit an 18” x 18” tile rather than 1/4” x 1/4” trowel.
12-inch Porcelain Tiles of Standard Thickness
A 1/4-inch by 3/8-inch square notch trowel will provide the right depth of mortar bed to beat a standard-size 12-inch porcelain tile into. A 1/4-inch by 1/2-inch U-notched trowel will also provide a thick, even bed.
Tiles are commonly referred to by their "nominal" sizes which might not be the "true" measurement of the material. An example of this is when a 12" x 12" porcelain tile has a "true" measurement of 11-7/8" x 11-7/8".
For example, you'd use an 12mm notched trowel when tiling 10-inch tiles on an uneven floor. It should be noted also that, for floor tiling, a minimum of 10mm trowels would be used to ensure there is enough contact on the back of the tile to make sure there are no voids.
The shape of the notch affects how much thinset the trowel will spread. A V-shaped notch will spread the least amount of thinset, a square-shaped notch will spread the most thinset, and a U-shaped notch is somewhere in between.
If you're working in a small area with a small tile, such as a 3x12” subway tile on a backsplash or fireplace surround, you can usually have small 1/16” or 1/8” grout lines.
In addition to producing an uneven surface, applying too much thinset can create costly cleanup headaches and add unnecessary time to a project. Simple installation rules eliminate the possibility of this potential problem.
½ inch x ½ inch square notch trowel
You want to use this for most tiles that are 16-inches and larger. So, this is a good trowel size for 12×24 tiles, 16×16's, 6×24's, 8×36's, wood-look plank tiles, etc. Additionally, it's a good choice for natural stone tiles 12×12 and larger like marble, granite, and travertine.
Thinset that has too much water will be runny and droop off of the wall and cause the tiles to sag instead of hold in place. What happens if you don't put enough water in thinset? If thinset doesn't have enough water it won't stick to the surface or smooth out to an even layer.
Tile set by the thinset method is adhered to the substrate with a thin layer of "thinset" cement. This type of cement is designed to adhere well in a thin layer - typically not greater than 3/16th thick." Tile substrates are allowed 1/8" of variation from one area to another (and typically have more than that).
The mortar should be fairly thick, like thick peanut butter. The thickness and consistency of the initial mix should be the same consistency of the final mix. Slaking is necessary!
Since the tiles available today are made with a low porosity level, there is no dipping requirement. Also, especially for wall tiles, many masons have started using adhesives for installation and not cement and mortar, the challenging task of wetting the tiles in water is no longer needed.
Fiber cement board (also called fiber board), is constructed from Portland cement mixed with sand and cellulose fibers. Fiber board is recommended for floor tile installations as the make-up of the board helps adhesives to bond with the board itself.
What is back-buttering? Today, the tile industry is mainly focused on porcelain tiles. It is strongly advised to back-butter tiles, especially large-format tiles and porcelain tiles. Back-buttering consists in applying a thin layer on the tile backing using the flat side of the trowel.