Ceramic tile provides a beautiful and decorative surface, and functionally it provides a surface that is not affected by water. However, this is not to say that tile delivers a waterproof assembly. What it can do is protect those areas which are vulnerable to water damage—when installed properly.
Around residential bathtubs in many parts of the country, the building code requires the ceramic tile to extend beyond the wet area a minimum of two inches. This includes the vertical area along the face of the tub, in order to protect the adjacent surface which is usually gypsum wall board. While this area should not normally be subjected to water, it can occur.
When installed and properly maintained, shower doors keep the water inside the tub area. However, shower curtains can be more problematic. If the curtain doesn’t provide a tight seal to the wall, water can travel along the top rim of the tub and flow down the tub face. When the code requirement for ceramic tile is not met, the water encounters the drywall…which is now no longer dry. The water saturates the wall, causing it to deteriorate.
As you can see in the attached photo of a hotel bathroom, the heavy commercial vinyl wall covering is bubbled out beyond the normally flat face. When the vinyl is pulled back, the usually “dry” wall is now saturated with water, compromising the integrity of the gypsum wall board. It must be noted here that this is not indicating that gypsum wall board is an inferior product, but rather the builder used the wrong product in this location.
This entire situation (or, more accurately, failure) could have been avoided had the appropriate backer board been used in lieu of the gypsum board. Another way to eliminate this problem is to apply either a sheet or liquid waterproofing membrane per the manufacturer’s recommendations over the entire shower wall area, which would include the two narrow strips or legs along the face of the tub.
Just a little more tile and the appropriate substrate can make the consumer happy, yielding another beautiful and long-lasting tile installation worked on by qualified labor.