QUESTION
I wonder if you can help me out on a problem we are having based on coved lighting that causes the wall-washing effect.
We have a project we did a year ago where we installed 3” x 6” wall tile at the restroom walls; at the wet walls there is coved lighting. When they turn on the lights, the installation looks horrible at the walls with the light cove. Do you have any information about light placement, and what is the allowable variance in the actual tile-to-tile installation, and also information how to resolve this besides tearing out the walls? Thank you!
ANSWER
In Chapter 6 of the NTCA Reference Manual there is a section called Critical Lighting, as well as a Lighting and Tile Installations section in the TCNA Handbook for Ceramic, Glass and Stone Tile Installation. They both address this problem. There are also standards in both TCNA and ANSI about allowable lippage. For the tile and grout joint size you are using in this installation, the allowable lippage is 1/32″, which is about the thickness of a credit card.
The sections about lighting explain how installations that meet industry standards for lippage can look poorly under these lighting conditions. Some installers in the same situation will turn off the lights and put a different light source on at a different angle on the same wall. They then document both lighting situations with photos, showing this to their customers to explain the effect light can have on the appearance of the installation. I would check to make sure the installation is in tolerance for lippage. Then, I would take the NTCA Reference Manual and TCNA Handbook to your customer showing them what our industry says about this type of lighting. I hope this helps.
Robb Roderick, NTCA Technical Trainer
