The thought that “tile is tile and it can be used anywhere” can be a recipe for failure. Given the popularity of installing marble tile on bathroom floors and walls, it seems sensible to also use the marble in the shower. But the homeowner contemplating using it in a shower should do their homework before proceeding. This article is not intended to malign the stone industry in any way, but rather to provide consumers and installers with information to aid in making a suitable selection.

When a person is shopping for tile, especially a natural stone product, they should always determine if the product is recommended by the fabricator and the salesperson for use in a conventional stall shower. Ask if the chosen stone tile has any concerns when used in the wet environment of a stall shower which will also generate a significant amount of moisture vapor. Some suppliers of these products indicate that it can be used on shower walls while other suppliers say that the tile may not be suitable in that atmosphere. 

If the project calls for natural stone in a steam shower, be extremely cautious and ask a lot of questions. Natural stone products vary in their water absorption rate but are generally more absorptive than a porcelain tile. Since natural stone tile is quarried from the earth and is not a manufactured product, it can contain various minerals in distinctly different concentrations that can be activated by the moisture vapor in a standard shower. When this occurs, the minerals are carried to the surface of the tile where they appear as an unusual color or stain.

Tile Shower Case Study

This was the case of an upscale stall shower completed by a high-quality tile craftsperson. The installer followed the American National Standards Institute (ANSI) requirements, the Tile Council of North America (TCNA) Handbook methods and details, the installation recommendations of the waterproofing and mortar manufacturer, and tile industry best practices.

Before installing the 12” x 24” Statuarietto polished marble, the installer brought the yellow/gold discoloration to the attention of the client, stone supplier, and builder who said to proceed with the job. The installer cautioned all parties concerned that the yellowing could be an issue in the future. The project was completed and looked great. However, eight months later, the iron oxide (rust) discoloration is clearly evident.

This shower did not have a fan to allow the moisture vapor to escape and the client closed the shower door immediately after using the shower further exacerbating the problem.

We could also discuss the practice of sealing the marble before and after installation, but that is a lengthy and complicated discussion for a different day.

Notice that all staining occurs on the ceiling and down to the wall midpoint, but the lower areas and the floor exhibit no discoloration. This occurred due to the moisture vapor being concentrated in the upper areas. As it cools, the vapor becomes a liquid which is considerably less damaging.

Stone Tile Installers: Proceed with Caution

If you are contacted to install stone tile, especially light-colored marble, on shower walls and ceilings, proceed with caution. Ask a lot of questions, know the facts about the stone and its characteristics before proceeding. Unfortunately, after installation, if discoloration develops, the installer is usually on the hook to replace the odd-colored tile at his or her expense. Sadly, removing and replacing these tiles may not solve the problem. The replacement tile may likewise discolor making the situation unsolvable.