Crack isolation issues seem to hit a nerve with more than a few installation contractors (check out Crack Isolation: a technical look at a challenging subject in this issue for a technical story on this subject).

At CTEF, we receive calls and emails on other paper-type or sheet-vinyl systems that appear to work but aren’t an industry-approved product or method. A few respondents insisted that their methods had never failed them in the past 10, 20, or even 30 years.

Before we get into the technical end of things let’s look at just how accurate the statement “never had a failure in XX years” really is. I used to find these statements intimidating when I indicated that a claim should be expected if procedure “x” is done using product “y”. The reality of asserting decades of problem-free installations is that contractors really don’t know what happens to the job.

Let’s be honest: how many of you out there truly know how your past 100, 1,000, or 10,000 installations are performing? Do you make annual visits for a check-up? Do you call past customers a few years later to see how things are going? No, nobody does. When the job’s done you get the check and breathe easy when the one year warranty is over and feel even better when they sell the house in the average 7.4 years. That is reality.

Once again, a strange substance appears in the grout joint. This time is proves to be roofing felt installed with multipurpose flooring adhesive

The only possible exception to this rule is if you have a fixed place of business and have been there for 10, 20, or 30 years. Anyone making the 10, 20, or 30 year statement that is backed up by real estate and not a set of wheels, is a lot more credible. Strangely, in my experience it always seems to be the wheel-based guys speaking the loudest.

I think a lot of the resistance to good sound advice on membranes or any other topic has much to do with the “me versus the industry” mentality. If you are reading this, you are part of the industry. Every TileLetter reader is an industry member in some aspect.

Working for an industry-based organization is quite different than the 28 years I spent as an installer. The questions that arise for a member of an industry-based organization are much broader in scope than one sees on a local level. National organizations such as NTCA, TCNA, CTIOA, and CTEF get calls and emails seeking information from all over the U.S., even some from Canada, Mexico, and other countries in the Americas. Due to the huge volume of calls over a wide range of issues and large geographical area, specific patterns of problems and product issues become very clear. This holds true for products continually used for purposes they were never intended or designed for. We get to see a bigger picture than most do on a local level. All of the above organizations and many others regularly receive calls and emails about felt, paper, and sheet vinyl systems for crack isolation

Now onto the technical stuff…
Roofing felt, along with various other paper products and sheet vinyl with unknown values, when glued or unglued to concrete slabs have a long history of failure. The products typically lack the performance features and criteria that would allow effective control of concrete fractures and wood movement without transmission of cracks through the finished tile surface. They exhibit low bonding strength against the expansion and contraction of both the tile and the substrate. In the case of concrete, these products are not designed for prolonged moisture exposure common in a bonded application.

The complaint on this floor was cracked tile and grout. The installation was found to have lost its bond between the thin-set mortar and roofing felt.

A while back I received a call from a national homebuilder that gave some interesting statistics on the effectiveness of their use. Prior to using the glue-down felt method over concrete they were experiencing a 40 percent failure rate during the warranty period. Using roofing felt cut the failure rate down to 20 percent. They found this risk to be acceptable, as the subcontractor was always judged liable and provided free repairs or replacement. There are many fully warranted and industry approved membranes that probably would cut the product failure rate down to 0 percent. Due to minor cost differences this builder was not interested since he had a ready source to assume liability during the warranty period: the tile contractor. After the warranty period that liability would pass to the consumer.

It is worth noting that except in the case of gross error, installation or otherwise, ceramic tile floor systems usually pass through several years of seasonal changes before such failures to take place. This is due to minimal seasonal or thermally-induced movement of the installation relative to the force required to produce failure. (Installations that have “tented” – that is rise from the floor surface-- also typically have no movement accommodation joints at the perimeter as recommended by all tile, membrane, and installation material manufacturers and contained in industry guidelines.) These products and methods continued to be widely used. The initial financial savings realized by using such inferior methods and untested products often results in a huge replacement cost to the unsuspecting end user at a later date.

The NTCA Technical Committee recently adopted a position paper soon to be published in the Reference Manual to address the use of unsound materials and methods used for crack isolation and waterproofing. With 32 members and 33 guests -- some of the best minds in the business -- the proposed document passed on an affirmative vote with little discussion. We feel it is very important to both protect and inform our members that use of these types of products carry an associated risk. (Ed. Note: the actual felt alert will be published in a future issue of TileLetter.)

© 2007 David Gobis. David M. Gobis, a third-generation tile setter, is the technical director of the Ceramic Tile Education Foundation. He has been in the trade for over 30 years and owned a successful contracting business for many years prior to his current position. Mr. Gobis is a member of the NTCA Technical Committee, Construction Specifications Institute, International Code Council, American Society for Testing of Materials, The American National Standards for Ceramic Tile Installation and Setting Materials (ANSI A108/118) and TCA Handbook committees. He can be reached via email, dave@tileschool.org.