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Tile Talk November 2019 | Five Frequently Asked Questions (FAQ) About Tile

This month I wanted to do something a little different.

As you guys already know, I oversee all aspects of quality assurance and quality control for our tile division.  My scope and responsibilities range from reviewing tile specifications in early schematic design to assisting with post jobsite issues and concerns at the contractor level.  This means that the type of questions that my department will come across are wide and varied.  From understanding TCNA substrate requirements for a proper on-grade installation to assessing efflorescence and leaching in latex modified grout – the types of questions I receive are unpredictable.

To better identify, understand, and organize these questions – I first had to quantify all the information into subcategories.  This undertaking revealed to me (with a certain degree of surprise) one thing – I get asked the same questions a lot!   So, I wanted to share with you the 5 most frequently asked questions (FAQ) and issues pertaining to tile that I’ve received over the past 3 months.

By the way, these are in no particular order…

1. Why am I seeing lippage?

As I mentioned in my July blog, lippage isn’t the result of a singular factor.  Many times, it is the combination of several factors.  In order to best minimize lippage in a finished installation, remember these tips:

  • Floor prep is not voluntary – it’s mandatory. Filling in lows spots and flattening out high points sets up the foundation for a smooth and flat surface.
  • Utilize proper joint size – The grout joint should be 3 times the facial dimension variance for the specified tile. For example, if the tile has individual pieces varying 1/16” in size, then the grout joint utilized should be 3/16”.
  • Lippage control systems are your friend – The larger and more complex a tile and pattern are, the increased likelihood for the potential of lippage. These mechanical leveling systems serve as both grout spacers and leveling clips.  Consider LCS clips for large format, thin-gauged, and plank-style tiles.
  • Specifying proper offsets – All tiles have an inherent crown present near the center of the tile. This means that tiles are not perfectly flat.  Tiles greater than 18” on any one side cannot be offset more than 33% of its length.
  • Single sourcing – Stick to single sourcing the tile for your project, or limiting to a few trusted partners. A good supplier will confirm appropriateness of materials through the manufacturer, and will provide proper guidance on their product offering.

2. There is a crack in the tile. What would cause this?Cracked tile

Tiles are incredibly strong and durable.  The breaking strength and modulus of rupture are unmatched for hard finished surfaces.  However, tile is only as strong as the foundation it sits on.  And in this case, we are talking about mortar.  Follow these steps and say goodbye to cracks.  (Assuming the substrate meets TCNA deflection requirements and is structurally stable)

  • Minimum 80% mortar coverage is required – no spot bonding! Minimum 95% coverage required for wet or exterior applications.
  • The substrate that tile bonds to moves, expands, and contracts. Movement and expansion joints are always required.  Follow the guidelines of TCNA EJ171 movement standard.
  • Proper troweling techniques – Swirling trowel marks is a big no-no. Always play it straight and use the right size trowel.


3. What is DCOF and how do I use it properly?
Measuring the DCOF rating of tiles

Dynamic Coefficient of Friction (DCOF) is the frictional resistance one pushes against when already in motion.  For DCOF, a slip occurs when pushing off with more force than the surface can resist.  In North America, the tile industry uses the DCOF Acutest per ANSI A137.1 to measure the DCOF rating of tiles.  According to this standard, ceramic tiles selected for level interior spaces expected to be walked upon when wet must have a minimum wet DCOF Acutest value of 0.42.  However, having a rating below this rating, or higher than this rating does not automatically determine suitability or appropriateness of the tile.  Type of use, traffic, maintenance, and wear are important and must be considered by the specifier.

4. Are ceramic tiles appropriate for exterior applications?
Business Porcelain Tile Slate Installation

Ceramic tiles that absorb less than 3.0% of water or moisture and meet or exceed freeze/thaw cycles (ASTM C0126) can be used in exterior applications.  However, industry experts feel that only porcelain tiles that absorb less than 0.5% water/moisture and meet or exceed C1026 freeze/thaw cycles should be used.  And remember, exterior applications require 95% mortar coverage below the tiles.

5. Are there any toxins in porcelain tile?

Nope!  Porcelain tiles are free of petroleum, formaldehyde, volatile organics, and toxic chemicals.  In fact, it is one of the safest finished products out there.  The three basic components are clay, feldspar, and sand – all naturally occurring elements that come from the ground.  For a detailed response to this question, check out my full blog from this past summer.

Well, there you have it!  Come back and check out my next blog in January of 2020.  We’ll jump into gauged tiles and panels – and my top tips/tricks for a successful installation

See you in the new year!