Methods and Standards: Recent Proposals for the Upcoming TCNA Handbook
By Kevin Fox, NTCA Methods and Standards Committee chairperson
The NTCA Methods and Standards Committee’s work over the last two years reaped great success at the TCNA Handbook meeting in Atlanta, Ga., recently. There were six proposals submitted, and with great help and guidance from the TCNA staff, all were approved. Following is a brief summary on each of them.
I believe our proudest accomplishments are new sections on design and evaluation criteria pertaining to finished installation appearance. These new sections are as follows:
- Under the section GROUT JOINT SIZE AND PATTERN CONSIDERATIONS, you will find two new sub-sections, “System Modularity” which clears up confusion on modular tile sizes, gives design professionals guidance on using different sizes together, and points to the simple truth that when the tile modularity is not understood, design compromises are inevitable. The second new sub-section is “Tile Layout” which gives general tile layout provisions addressing reasonable expectations and limitations that challenge most projects.
- Under the section USING THE TCNA HANDBOOK FOR SPECIFICATION WRITING, a new sub-section called “Design Considerations When Specifying Tile,” references the Handbook’s many sections that design professionals must familiarize themselves with that impact the selected tiles and designs. It gives a very important reference that strongly recommends industry standards, guidelines, and best practices to be followed and strongly discourages variances from them. It also recommends in-situ mock-ups to be used under the given job site conditions.
- Under the section FINISHED TILEWORK, is a new sub-section called “Visual Inspection of Tilework.” This will be extremely helpful for the industry. It recognizes the hand-build aspect of tile installations, references substrate requirements, lippage, allowable warpage, effects of lighting and many more factors that affect the installation visual and aesthetic appearance of the finished tilework. It also gives guidance on viewing distance and lighting when finish tilework is being inspected.
EJ171 movement joint guidelines
Another accomplishment, with substantial consultation from Crossville’s technical staff Noah Chitty and Tim Bolby, was major additions to EJ171 MOVEMENT JOINT GUIDELINES. Most notable changes are recommendations in movement joint width and depth. The additions give a chart for minimum movement joint widths (for dry interior, not exposed to sun) in relation to joint frequency and tile thermal expansion properties, along with reference to the proper ASTM guides for calculating the joint.
Another addition to this section is a new sub-section called “Wall Tile Movement Joints in Framed Wall Assemblies” (with substantial consultation with Tony Fuller of National Gypsum) which gives the design professional awareness that wall movement joints are unique and require consideration of other wall components such as sheathing, framing and backer board before the wall is constructed – and that such considerations many times cannot be retroactively added.
Lighting and tile installations
Many of us are familiar with the effects lighting has on an installation. A substantial new Lighting and Tile Installations section has been added to give importance to this issue which can lead to much heartache for all involved. The majority of the added language was taken from the NTCA Reference Manual, so for many of you this will look familiar.
Mortar and mortar coverage
There was also language added to the MORTAR AND MORTAR COVERAGE section noting 100% mortar coverage is not practical. Many specifications call for 100% mortar coverage but this cannot be consistently attained and therefore it should not be specified.
It has been well-established that mortar cure times are extended when impervious tile is installed over waterproof or crack-isolation membrane. To alert design professionals of this situation, language has been added to the SETTING MATERIAL SELECTION GUIDE. Other conditions that will also delay cure times are narrow grout joints and using high-performance grouts. Recommendations of extending turnover of the floor to traffic are given.
Membrane selection guide
Other language added pertaining to membranes is in the MEMBRANE SELECTION GUIDE. A new sub-subsection called “Considerations When Using Membranes” that not only references the above-noted extended cure times for mortars, but also the fact that the hollow sound of tile installed over membranes is normal and not indicative of loss of bond (without concomitant installation issues).
The last submission involved the continued discussion of the disparity between division 3 and division 9 floor flatness. The section on SUBSTRATE REQUIREMENTS gives many references to this. The language we submitted further clarifies this difference. One of the key points to note is when division 3 floor flatness (FF) levels are specified, the floor must be verified to assure the specified levels are attained. This may seem implied, but many times this test is not performed. Therefore it quickly becomes a source of tension for projects when it’s required to correct the floor to division 9 specifications, and the tile contractor requests to be compensated for the work. This also leads to another important addition to this section: recommendations for the design professional to incorporate a separate allowance to correct the floor flatness from division 3 to division 9 specifications.
As chairman of the Methods and Standards Committee, I want to thank its members, the gentlemen from Crossville and National Gypsum mentioned above, representatives from MAPEI, TEC and Bostik, and the TCNA staff for helping us with these submissions.
Our next meeting with be October 22 at the Hyatt Regency Indian Wells Resort & Spa in Indian Wells, Calif., during Total Solutions Plus, October 22-25. If you have topics you feel would be appropriate for this committee to consider, you are welcome to contact me at [email protected].