Checking for proper coverage in a tile installation

The National Tile Contractors Association tries very hard to answer questions that arise in our industry regarding proper installation of ceramic tile. It is a daunting task. Unfortunately, a significant amount of calls we receive are from unhappy consumers who have a problem, perceived or real, with their tile installation. If we do get a call from a contractor or dealer responsible for the installation, it is generally a reactionary one; in other words, the job has been done and someone is unhappy or the installation is failing.

If I make any point that needs to be noted in this article, it is the following: Many problems can be avoided if you consult with experts prior to performing a questionable installation. It sounds so simple. Yet it remains one of the leading causes of installation failure in our country.

A few years ago, the Tile Terrazzo Marble Association of Canada (TTMAC) published an article authored by Dale Kempster of Schluter Systems titled "The 10 Most Common Tile and Stone Failures." It is an excellent article and I recommend you get a copy of it if you haven't seen it. The NTCA then sponsored a presentation by Kempster at Total Solutions 2004, our annual educational event held each year in the fall. It was here where I decided to start keeping track of our technical calls and emails, with the intent to compare the TTMAC article to what we were hearing at our offices.

With a year of valuable data now collected, four distinct categories of Types of Failure have emerged the winners (or losers).

#1 Improper Use of Materials and Lack of Following Instructions
This was a clear-cut winner, accumulating 35 percent of the calls that we tracked. The TTMAC article listed each one of these issues separately, but we found these types of calls to be closely related. Typical situations included the use of backerboards over oriented strand board (OSB) and plywood that did not meet the criteria as specified by the Tile Council of America and the manufacturers. Often times the thickness of the subfloor and the substrate were insufficient. Some very questionable methods are taking place in the market. Many calls we received indicated that the builder was dictating what to install the ceramic tile over, and threatened to switch subcontractors if they weren't willing to warrantee the floor or wall installation. I say go ahead and switch if your builder isn't willing to consider methods that are proven in our industry.

Specific examples of questionable methods that we chronicled included the following:
• Greenboard still being used extensively in wet areas as building codes are slow to change: SO WHAT! Just because the code is behind the times doesn't mean we don't know it is wrong to do this. Stop this practice immediately!
• Insufficient knowledge of concrete substrates: Curing compounds, sealed concrete, slabs that are not even close to meeting industry standards for flatness and levelness, and the continued use of products such as felt paper, wicking paper, scribing felt on concrete surfaces that are susceptible to moisture has led to numerous failures that have been reported to our offices.
• Improper Selection and Specification of Materials: Often times we install products that are doomed to fail or perform inadequately due to a bad specification, but we lack the initiative to question the supplier or consumer. Failure to do so leaves you at risk. You are doing everyone a favor to question if a product is proper for the specified area.
• Lack of Following Directions: I had one person tell me recently that it didn't matter what the installation warranty said, the manufacturer would find a way out of the responsibility of the claim anyway. He didn't like my response, as he was not following the specific installation requirements on the technical data sheet of this particular manufacturer. You are not helping yourself if you take this approach. I have found that the manufacturers genuinely want to solve and prevent problems. Often times they pay out in materials and labor costs when they really didn't have to. Nobody wins in a tear-out and replacement situation.

#2 Coverage, Coverage, Coverage
Improper trowel selection, improper technique, and improper mixing procedures lead to this issue. One manufacturer representative told me that almost one hundred percent of the installation failures he sees have inadequate coverage, even if this is not the real cause of the problem. The American National Standards for the Installation of Ceramic Tile Committee (ANSI A108) calls for a minimum of 80 percent coverage for all tile installations. In an exterior project, the requirement is 95-100 percent. The TTMAC points out to pay close attention around the edges of the tile.

The trends in our industry include an increased use of glass and metal, and a movement towards larger tiles and different types of stone. All of these products present challenges to a successful installation. Adequate coverage is vital now more than ever!

#3 Lack of Movement Joints
According to our research, we are beginning to make strides on this issue. More people in the trade recognize now the importance of proper placement and installation of movement joints in tile and stone installations. However, it continues to be a major problem in residential installations. With tile being used in larger areas in the home over greater spans, it is vital to address movement joints before the tile contractor begins the installation.

It is really about education. The TCA Handbook is clear on this issue. It is the responsibility of the architect or designer to properly specify movement joints and to indicate where they should be placed. The contractor needs to understand these requirements and can take a leadership role when they recognize when movement joints have not been specified. Don't make someone else's mistake your problem. Once you install the tile over an unsuitable substrate, you are liable.

When movement joints were improperly placed, or in many instances were not even considered, results varied. Buckling or tenting of the tile being pushed upward was commonly cited, while in many instances a loss of bond and shearing of the tile from the substrate occurred.

#4 Exterior Installations and Efflorescence
We continue to receive numerous calls, especially in balcony installations on or near ocean front property, on the issue of efflorescence. The presence of soluble salts on the surface of the tile or stone and in the grout joint can be extremely difficult to remove. There is new technology being introduced that may be effective in inhibiting or removing efflorescence, but the fact remains that this troublesome result of trapped moisture in the setting bed is a problem, especially in areas subjected to significant sunlight exposure.

Allowing the system to properly drain is a preventive measure that could be considered. When your client is considering this type of installation, research the systems designed for exterior decks and balconies, and take into consideration a proactive approach to minimizing moisture.

We will continue to track the nature of our technical correspondence with the industry. We receive emails at We also have a Message Board located on our website at where you can post installation questions and participate in dialogue with others who can either help solve your problem or share their issues with you. Don't feel embarrassed to ask a question. A proactive approach is better than a reactive one. We are all learning new things every day. Technology in the tile manufacturing industry puts pressure on the installation manufacturer to produce systems that work. This in turn creates a situation where the contractor is being consistently exposed to new ideas, products, and methods. The challenge is to move cautiously, but to keep an open mind. NTCA and other organizations are committed to continuing to conduct this research and to share our findings with the industry.