Faqs For Tile, Stone, Mosaics

Frequently Asked Questions (FAQs) About Tile and More
Welcome to Tile Outlets of America's Frequently Asked Questions about tile, stone, mosaics and more!

Tile Installation Information:

For information about tile installation, be sure to check out our tile installation tutorials and explore the products, tools and supplies available at Tile Outlets of America for your tile installation project.

Before getting started with your installation, be sure to read Managing Lippage: Why Offsets Matter When Installing Tile so you obtain the offset information you need to properly install your project.

>> See Create a Lippage-free Tile Installation with the Tuscan Leveling System

>> See Learn How to Use the Tuscan Leveling System When Installing Tile

>> See How To Install Tile Correctly and Get Proper Mortar Coverage

>> See How to Manage Moisture in Tile Showers: Schluter Training Session

>> See Perspective on Tile Installation Underlayment from NAC Products Expert, Steve Price

>> Discover NAC Products

>> See GoBoard Lightweight Backerboard and Point Drain Shower Kits

As you go through these FAQs, if you don't find the question - and answer - you're looking for, please contact us!

Tile Basics FAQs
What is the difference between ceramic tile and porcelain tile?

Porcelain goes through an added process, grinding the clay to make it very fine. When the clay is compressed, it becomes very dense and has very little moisture absorption making it ideal for outdoors.

>> See How Solid Is Your Porcelain vs. Ceramic Tile Knowledge?

Can I butt my tiles close together on the floor?

In a word, no. Stones that are mud set can be butted. Tiles, because they are fired, will have some size variation depending upon the amount of moisture in the clay at the time of firing. 3/16” grout joint is the smallest we would recommend.

Tiles that are truly rectified can be set closer, however some of the larger tiles will naturally have a slight warp. Rectified tiles are tiles that have been cut after firing to insure uniformity in size.

What is the difference between sanded and un-sanded grout?

What determines whether you use sanded or non-sanded is dependent on the size of the grout space. 1/8” or larger use must use sanded grout. Under a 1/8”, usually 1/16 or smaller, you have to use non-sanded in order for the grout to properly pack into the joint. Non-sanded grout is also recommended for installation of glass, metals, or other materials that can easily scratch.

>> See How To Apply Crystal Glass Grout? Jean Snell from The Tile Doctor Demonstrates
>> See Grouting Glass Tile: An Interview With Jean Snell Of The Tile Doctor

What size trowel should I use to set my tile?

Trowel size is dependent on the size of the tile.
- Up to a 14” tile, a ¼ by ¼ square notch is recommended.
- Above 14” but smaller than a 20” a ½ by ½ square notch is recommended.
- About 20”, a ¾” by ¾” is the trowel of choice.

Wall tile set with mastic is usually set with a 3/16” v-notch trowel.

>> See Trowels, Floats and Tiling Tools for more information about the trowels and other tiling tools available at Tile Outlets of America. 

Does it matter if I use gray or white mortar?

Only when setting stone. Stones are porous and the color of the mortar will influence the tile. Black or green stones should use gray mortar. All others should use white. When installing tile, some installers prefer white mortar when they are going to use a light colored grout.
Can I use mastic to set my floor tile?

Mastic is meant mainly for wall tile. The rule of thumb is to mortar the floors and mastic the wall. Mortar can be used to set wall tile; however, it is not very sticky and holding the tiles in place until they dry can be challenging unless you use a light weight flexible thinset.

What mortar do I use to set my tile?

Going over any other surface than virgin concrete you should use a multipurpose mortar ("pro" or "premium" flexible thinset). If you are setting a single fired tile or porcelain you should use a multipurpose as well.

Can stone be set the same as ceramic on the floor?

Stones set on the floor require “mud-setting”. There are different methods to doing a “mud-set”. The most common is to use a ¾” square notch to trowel the floor, then trowel the back of the stone or butter the back with mortar.

Can I go over vinyl flooring with my tile?

Using a multi-purpose mortar, tile can be bonded to vinyl flooring.  Two things to be careful of:
1. Is the vinyl coming loose?
2. Is the vinyl flooring spongy?

If the answer to either of these questions is yes, then going over the vinyl is not recommended. It is always better to adhere the tile directly to the substrate. The multipurpose mortar will bond the tile to the vinyl, but it will not prevent the vinyl from coming loose. In essence you are putting good money over bad. Direct bonding to the substrate is best.

When do I need to use crack suppression?

Crack suppression is used to minimize the tile’s exposure to stress from the slab.

Before setting the tile, you should walk the slab and look for cracks. If you only have a few cracks then you can use a crack suppression kit. If the slab is new or under three years old then crack suppression should be used on the entire area to be tiled.

>> See Why Underlayment Matters to a Tile Installation Project

Tile Technical Terms FAQs: What do they mean?
1)  PEI Rating – This rating system developed by the Porcelain Enamel Institute is the most effective means to determine the suitability of a particular ceramic or porcelain tile for its intended use. The rating system indicates a tile’s resistance to abrasion and likelihood to wear under use. The PEI ratings are as follows:

- PEI I – tile has lowest wear resistance and is suitable for wall use only
- PEI II – tile has low wear resistance and is suitable for wall use and for floor areas with light traffic such as residential bathrooms
- PEI III – tile has moderate wear resistance and is suitable for all residential uses and in commercial areas where light to moderate foot traffic is anticipated
- PEI IV – tile has high wear resistance and is suitable for all residential uses and all medium commercial and light industrial uses
- PEI V – tile has highest wear resistance and is suitable for all residential, commercial and industrial uses

>> See How PEI Helps You Select Ceramic or Porcelain Tile for Your Remodel
PEI Rating
2)   Water Absorption – A tile’s water absorption percentage is important in determining whether the tile is suitable for installation in a particular room or area. Expressed as a percentage, the rating measures how much water the tile absorbs in relation to its total weight.

- High absorption (non-vitreous) tiles absorb more than 7% of their weight and are not suitable for outdoor areas or wet area environments such as showers
- Moderate absorption (semi-vitreous) tiles absorb 3% to 7% of their weight and are not suitable for outdoor areas or wet area environments such as showers
- Low absorption (vitreous) tiles absorb 0.5% to 3% of their weight and are suitable for outdoor areas and wet area environments such as showers
- Lowest absorption (impervious) tiles absorb less than 0.5% of their weight and are suitable for all indoor and outdoor uses
3)  Coefficient of Friction (C.O.F.) – The C.O.F of a tile, expressed on a scale of 0 to 1, represents its relative safety to walk on without fear of slipping and is measured by the force needed to move an object across its surface divided by its weight. A low number indicates less friction and the likelihood the tile will be more slippery while a high number indicates greater friction and more traction thus increasing the likelihood it will be less slippery. C.O.F ratings are broken out as follows:

- C.O.F. of 0.60 or greater (wet) – indicates the tile is slip resistant, is suitable for all residential and commercial uses and meets or exceeds general safety and health regulations, ADA and OSHA requirements
- C.O.F. of 0.50 to 0.59 (wet) – indicates the tile is conditionally slip resistant, is suitable for standard residential uses and meets or exceeds general safety and health regulations and OSHA requirements
4)   Shade Variation – The shade variation rating of a tile indicates the degree to which its color, tone and texture vary among individual tiles. Virtually every ceramic and porcelain tile, other than pure black or white tiles, has some degree of shade variation even in the same production run. The Ceramic Tile Distributors Association has developed the following tile shade variation rating system:

- V1 = UNIFORM APPEARANCE – Differences among pieces from the same production run are minimal.
- V2 = SLIGHT VARIATION – Clearly distinguishable differences in texture and/or pattern with similar colors.
- V3 = MODERATE VARIATION – While the colors present on a single piece of tile will be indicative of the colors to be expected on the other tiles, the amount of colors on each piece will vary significantly.
- V4 = SUBSTANTIAL VARIATION – Random color differences from tile to tile, so that one tile may have totally different colors from that on other tiles. Thus, the final installation will be unique.

>> See How to Deal with Shade Variation in Porcelain and Ceramic Tile?
Shade Variation Guide
6) Dye Lot - A tile’s shade (dye lot) refers to the coloration and reflectivity of a tile. Since natural materials are used in both the body and glazes of the tile, slight variations in shade are normally inherent from one production run to the next. 
7) Caliber - A tile’s caliber refers to its facial dimension (size) and is measured with a tool called a caliper. Since natural materials are used in both the body and glazes of the tile, slight variations in caliber are normally inherent from one production run to the next. 
8) Inkjet Technology

>> To learn more, see How Inkjet Technology Has Transformed Ceramic and Porcelain Tile