Tech Tip Tuesday: Q & A With NTCA Training Director Mark Heinlein
I have a job where we installed a porcelain tile. It is 8” x 15” and the side walls are fine but the wet walls are not good. The worst part is they have that system of lighting where it is shining down directly from above so it shows all discrepancies and shadows. Is there anything in the industry standards that allows for a tolerance for a little lippage?
Thank you for contacting the National Tile Contractors Association.
The standard for lippage is found in ANSI A108.02 Section 4 (copy attached) and is echoed in the TCNA Handbook. Generally speaking, 1/32” in addition to the allowable warpage of a tile manufactured in accordance with ANSI A137.1 is the allowable lippage for wall mount mosaics with a grout joint width of 1/16 – 1/8”.
I understand these strip mosaics can be difficult and time consuming to install. You are correct that substrate flatness is the place to start to help ensure the installed lippage is within tolerance.
The NTCA Reference Manual has an excellent section describing Wash Wall Lighting and how to avoid problems that can be associated with it. If you have your Reference Manual at hand, it will provide some good reading on this topic.
The 2017 TCNA Handbook contains a section on Visual Inspection of Finished Tilework. I don’t have my book close at hand but it is in the first 30-40 pages. It may help your situation that visual inspection of wall installations is performed at 36” from the tilework. Please take a look at that section in the Handbook and see if it can work for you in this case.
Please let me know if I can help with any further questions you might have after you are able to review the documents I listed above.
I hope this helps!
NTCA Training Director