The latest edition of the TCNA Handbook for Ceramic, Glass, and Stone Tile Installation includes technical changes as well as two full-color guides full of new and updated quick-reference bulletins and articles.
Minimum shear bond strength for uncoupling membranes
When the “uncoupling membrane” made its debut in the ‘90s, it showcased a new approach to setting tile on floors over concrete and wood substrates. The term “uncoupling” was chosen to refer to the membrane’s function, as described by its manufacturer, of keeping the tile separate —uncoupled — from the substrate. Today, there are at least a half dozen manufacturers of this membrane type, and they have been collaborating on a generic ANSI standard that defines and quantifies uncoupling membrane performance.
But developing a product standard is not a fast process. Progress on this particular standard has been challenging, given the performance claims made and lack of existing test methods to evaluate those claims. The technical staff members working on this standard have to develop new protocols and possibly new testing equipment.
Although a generic ANSI product standard for uncoupling membranes is the ultimate goal, differing views, competition among manufacturers and the need for new tests make this very much a work in progress. As an interim solution, the Materials and Methods Standards Association (MMSA) proposed including in the Handbook a bond strength performance requirement. The MMSA’s proposal, approved by the Handbook Committee, was a 50 psi or greater bond strength requirement for uncoupling membranes when tested using the bond strength test method for crack isolation membranes provided in ANSI A118.12.
Handbook users will find this requirement in the Membrane Selection Guide, as well as in the Materials section of each Handbook method that requires or allows use of an uncoupling membrane. This approach is similar to that of other non-standardized installation materials in the Handbook like cementitious self-levelers and poured gypsum underlayments, which carry compressive strength requirements and Robinson Floor Test performance requirements.
With the addition of this bond strength requirement, the methods that include uncoupling now provide a mechanism to address what is reportedly the most common issue when there are problems: loss of bond. If such issues occur, with a criterion now set for minimum bond strength, better agreement can now be found with regard to the cause of a failure.
ANSI A118.15, Improved Modified Dry-Set Cement Mortar
A new ANSI classification was adopted last year to characterize higher performing thinset mortars. Previously, under the existing ANSI A118.4 mortar spec, which classified a wide range of mortars, meeting the A118.4 specification did not allow for a distinction between the highest performing mortars and those with acceptable but lower bond strengths. This made it impossible for specifiers to call out higher performing mortars when needed without naming specific products, as opposed to a generic standard. Similarly, when estimating, contractors had to decide whether or not to factor in a higher-performing (and likely more expensive) mortar, when a job spec called out A118.4. Given the competitiveness of bids, doing so could jeopardize the chance of getting a job by adding cost to a bid, but experienced contractors and estimators know that some installations and applications need, or would at least benefit from, a higher-performance mortar, even if the job spec doesn’t require it.
The new A118.15 standard for “improved, modified” mortars helps create a more level playing field for contractors by enabling a job spec to now call for a higher performing mortar, so contractors are clear on whether or not to include such mortars in their bids. Clearly this improvement benefits all: Specifiers have generic criteria for the mortars needed for demanding installations, contractors can bid more confidently and consumers get a better installation.
In the 2014 Handbook, A118.15 mortar has replaced A118.4 mortar for tiling above-ground balconies and decks, pools and steam showers. For interior above-ground floor methods, such as F113A, the mortar requirement depends on whether or not a crack isolation or waterproof membrane is being used. If not, the higher bond strength of the A118.15 mortar is required. In the same above-ground methods, if a membrane is used, an A118.4 mortar may be used. Similarly, A118.15 mortar is required when a membrane will not be used in the Handbook’s radiant heat floor methods and exterior wall methods.
To test bond strength, a loading plate applies shear (horizontal) force to the prepared test sample.
Flip to the full-color section of the 2014 Handbook to see information on a variety of topics and issues including sustainability, installer certifications, the coefficient of friction (COF) standard, and the problem of falsely labeled porcelain. Of particular noteworthiness is a 10-page guide to LEED v4 and tile, which is organized by “credit category,” similar to the way in which LEED v4 is organized.
This guide explains and offers examples of how ceramic tile can be incorporated into projects in order to meet LEED criteria in six LEED v4 credit categories: Materials and Resources, Indoor Environmental Quality, Sustainable Sites, Integrative Process, Energy and Atmosphere, and Innovation. For building design professionals designing to LEED v4, this information-packed, fast-reference guide is a must-have resource.
Two additional informational pieces focus on the importance of using qualified contractors and installers. The bulletin “Choosing Your Tile Contractor” lists important issues to consider such as contractor investment in training and continuing education; licensing and insurance; and a traceable business location. The TCNA report on ACT (Advanced Certifications for Tile Installers) provides an overview of the rigor and credibility of the installer certifications the ACT program covers: shower base installation; waterproof/crack isolation membrane installation; wall mud; floor mud; and large format tile installation including substrate preparation. Together, these pieces drive home how important it is to look at more than just price when selecting a contractor.
Another very useful piece is the one-page “What Is True Porcelain?” bulletin, which explains what constitutes true porcelain tile and provides an overview of the test method for determining whether a tile meets the water absorption standard for classification as genuine porcelain. As the article explains, some tiles are coming into the country claiming to be porcelain, but are not. This bulletin should aid distributors, dealers, specifiers and consumers in knowing what to look for and what to require when purchasing porcelain tile.
Where to find it?
The bulletins and guides described above (and much more) are included in the TCNA Tile Initiative, a full-color insert bound into the 2014 TCNA Handbook. The information is provided in “fast-reference” format, to facilitate quick and easy use and understanding by busy industry professionals. The Tile Initiative is also available as a free download (www.tcnatile.com). The technical changes made to the Handbook this year are only available by purchasing the 2014 TCNA Handbook, available in both print and electronic formats.