Houses move. The walls move differently from each other, the ceiling moves differently from the walls, and the floor moves differently from walls. If we add weight to a tub via a person and/or water, the movement is increased. These components don’t move a lot, but the significance is that they do move.
If there is ceramic tile on the wall attached to gypsum board, the problem can be severe. Ceramic tile is not flexible, nor is the grout between the tile. If there is not a high-quality silicone (flexible) sealant around the top perimeter of the tub and on the inside corners of the shower walls, a crack or hole can easily develop causing moisture to leak into the gypsum board. There can also be leaking around the shower fixture itself if there is not an adequate sealant. When the water wicks into the gypsum board, mold growth can occur on the paper on each side of the gypsum board and in the wall cavity itself. When this happens, the only correct repair is to tear the damaged materials out. These problems also occur when a plastic type shower surround enclosure is installed, but the potential leaking is somewhat diminished. Therefore, inspecting and repairing the sealant in the tub/shower area should be part of an annual maintenance program.
If gypsum board is installed in these areas behind the surround, it is considered improper, but the majority of installations are done in this manner. The proper substrate behind the surround is cement board. This cement board replaces the gypsum board. While there are still the same leaking concerns as gypsum board, the cement board will not support mold growth like gypsum board, and also does not delaminate.
*All of the above information is trademarked and is the property of RESTORx. We feel it is the most current and accurate information available but we do not guarantee it be the only proper solution. Written by Stephen Gitz, CR, WLS, CMP