Mismatch the Trowel Size
Make sure the trowel you use for the project matches the size of the tile. Larger tiles need a deep layer of thin-set, so you need a trowel with deep notches. When shopping for thin-set for larger tiles make sure the bag has terms such as "medium bed," "large tile" or "large format" on the bag label.
Crack the Tile
Depending on the material they're made from (think porcelain), tiles can easily crack. Too many ruined tiles can become expensive and wasteful. There are a few preventative steps to take to reduce the number of cracked tiles. The best tool to use when cutting tile is a diamond wet saw. When using the saw, make sure to apply slow, even pressure in order to create a precise cut.
In order for tiles to lay flat, the tile underlayment must be installed correctly. Vinyl tile is a good undelayment if it isn't damaged. A stiff base will also prevent the tile from cracking. If the underlayment isn't in good shape, put a 1/4- or 1/2-in. cement board underneath the tile to build it up.
Tile is Laid Out Incorrectly
When tile is laid out in a diagonal pattern, there are precise installation steps. First, center the tiles by aligning the corners with a single layout line. Then, build the rest of the pyramid design around that line. Use a straightedge to check the lines as you continue.
Don't let the beauty of your tile be overshadowed by bad grout Clear, clean grout lines make the tile look great and keep it looking new for years to come.
Improper Wall Preparation
Clean off all grease stains and finger prints from the walls before you tile them. If the walls aren't clean, the adhesive won't adhere to the walls and neither will the tiles. Follow these other prep steps to prevent having to redo the job.
Not Installing a Backer Board
If the tile is in an area with a lot of water, like a shower, you need to install a waterproof backer board. The backer board helps keep everything stiff, and this prevents water from seeping into tiny cracks. Read these tips to select the best backer board for your project.
Messy Caulk Lines
One of the final steps of a tile project is caulking. Here's the best way to apply caulk to a shower and tub.
Be Sure to "Back Butter"
When working with larger tiles it's imperative to back butter. Back buttering ensures a strong bond between the tile and the wall. Also, make sure the thin-set is mixed well and then let it sit for 10 minutes to ensure all the dry mix has absorbed the water.
Don't Skip Clean-Up
After the grout film has dried, polish away the haze with a cotton or microfiber towel or sponge.