To keep pace with the demand for new housing and to conserve energy, today's homes are being built faster and tighter. This can translate into less time for building materials to properly dry out, as well as less air infiltration and circulation in the finished home. Add to these factors the different types of water and moisture leaks that can occur - plumbing leaks, roofing leaks, even leaks under and around windows and doors - and every home has the potential for moisture damage and mold growth.

When the right conditions are present - a food source, a source of moisture, and a temperature of 45 to 90 degrees F - mold spores can grow on any surface, including floors, walls, and ceilings. No home is completely mold-proof, and while homeowners can take precautions to help minimize the potential for such problems, the first and most effective line of defense begins with the building products that an installer or builder chooses.

Photo courtesy of USG Corp.
Depending on which interior products are installed and a homeowner's maintenance habits, a bathroom can be a particularly ideal environment for mold to thrive in. Shower walls are continuously exposed to water, water splashes out of tubs and showers onto the floor, and moisture (in the form of steam) finds its way throughout the room. Unfortunately, mold growth is often undetected until it becomes a serious problem because it's often well hidden under wall and floor tiles.

If you're installing floor tile on a bathroom subfloor other than concrete, chances are you're using a cement or gypsum backerboard. Before deciding on which backerboard is best suited for wet areas, it's recommended that you first:
  1. Consult the 2006 Tile Council of North America Handbook. According to the TCNA, cement board and fiber-cement board are "recommended where water resistance is desired." Coated-glass mat water-resistant gypsum board, on the other hand, is "not for areas subject to continuous water immersion." Similarly, fiber-reinforced water-resistant gypsum backer board is recommended for use in "dry or limited water exposure areas." For more information or to view the TCA handbook, visit
  2. Determine if the backerboard you are considering achieves the best possible score on the ASTM (American Society for Testing and Materials) tests for mold growth - ASTM G21 and ASTM D3273.

Following industry guidelines and selecting a proper backerboard designed for wet area installations can have a major impact on reducing the potential for unnecessary moisture damage and mold growth in your remodeling projects and in today's new homes.