If you bought a car made in 1937, it wouldn’t include power steering, intermittent wipers or a single cup holder. It traveled at slower speeds, went fewer miles on a gallon of gas and spewed far more pollutants.

A telephone in 1937 was tethered to the wall and included a rotary dial—or none at all; it might have required you to ask an operator to connect you. The lawnmower had to be pushed, the phonograph wound.

All have been replaced by superior technology.

The same is true for the waterproofing system for a tiled shower floor. Yet many people still buy and install the old “mud pan” system, invented in 1937. A mud pan is designed to capture dirt, grime and moisture washed from your body each time you shower. It all seeps through the tile grout into the top layer of the mortar and then, theoretically, drains out the moisture through the material underneath the tile. All this nasty stuff is hiding beneath your tile floor.

But that’s only if it works properly. Once the pores in the mud pan get clogged with exfoliated skin, mineral deposits and debris, the draining slows. That can lead to the growth of organic colonies in the mud pan. “About 90 percent of the shower pans we pull out have black mold,” says Tommy Davis, president of KBRS, Inc., a company that manufactures a new and improved system.

Mold in your shower floor may or may not be a problem for you and your family. But you should know that the Institutes of Medicine determined a decade ago that there is a link between indoor mold and upper respiratory tract problems, such as coughing and wheezing, in otherwise healthy children and adults. The link extends to people with asthma and those with compromised immune systems.

Davis doesn’t think anyone should be installing waterproofing conducive to mold growth in showers when there’s an alternative. “Mud pan was the only system available in 1937; now it’s antiquated,” he says.


After years in a family-owned plumbing supply business, Davis started KBRS nearly two decades ago. Having installed “mud pan” systems for years, he recognized the need for an alternative and began engineering and manufacturing technologically advanced shower systems. An avid surfer, Davis developed his patented product using his knowledge of the materials that make up surfboards. Today, Davis is the continent’s premier manufacturer of “wet area” substrates.

KBRS’s patented shower pan, called a Tile Basin, manages interior and exterior moisture and helps prevent mold growth. It comes fully waterproofed with a waterproofing membrane developed by KBRS that’s like liquid rubber. The same waterproofing can be applied with a paintbrush or roller between tile and drywall. “We have a saying here at KBRS,” says Davis, “you can’t over-waterproof a shower.”

KBRS installs the product for its customers to ensure that it is properly constructed. Davis says many manufacturers warranty their products, but the warranties don’t have much value to consumers because “the products are perfect when they leave the factory, but the problem is almost always due to installer error.” When problems arise because a contractor or do-it-yourselfer fails to follow the directions exactly, the manufacturer’s warranty doesn’t apply.

When KBRS installs its Tile Basin system beneath your shower floor, it also provides a lifetime warranty on both the product and the installation. If something goes wrong, there’s only one company to deal with. Davis says his company is the only manufacturer in its field to offer a warranty on installation. “We want to make sure every one of our products is installed correctly,” he says.

How can a homeowner be sure that their waterproofing system is up-to-date? Anyone building a home, or remodeling one, can visit KBRS vendors (Buck Lumber, Wilson’s Carpets Plus or Carpet To Go and more) to buy tile, then arrange for KBRS to install the shower system. Alternatively, they can contact KBRS directly before installing tile. In either case, proper installation means an end to mold in the shower.

BARRY WALDMAN is chief thinker and doer at Write Stuff Communications.