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There’s no doubt: Water is invasive. And when it comes to windows in the shower, remodeler Christopher Wright says, the most vulnerable areas are where two materials meet. Fortunately, he adds, improved substrate technology makes it easier to create a water- and vapor-tight envelope under tiles and around windows — but how you combine those materials is important.

Wright, the owner of WrightWorks, in Indianapolis, says that his first choice for a shower window is glass block. “With glass block you can make a waterproofed opening, set the glass block, and apply materials to the perimeter where the tiles meet [the block] to create a watertight opening,” he says.

He primarily uses Georgia-Pacific’s DensShield Tile Backer — installing the material over the framing. Once the mortar on the seams of the DensShield boards is dry, he applies a surface waterproof barrier (Custom Building Products’ RedGard or Laticrete’s Hydro Ban) on the seams and on the screw heads. “If, over time, water penetrates the grout, it has nowhere to go,” Wright points out.

He cautions that the waterproofing does not bridge gaps wider than 1/8 inch. After he installs glass block in the opening, he paints the waterproofing around the perimeter of the glass block.

Staying Dry

Michael V. Crossman, owner/partner at New View Construction , in Brunswick, Ohio, has a different method for achieving a waterproof substrate. He covers all walls, framing, and fasteners with Wedi Corp.’s Wedi board , a lightweight underlayment consisting of a foam core, glass fiber mesh, and cementitious coating. Crossman also uses the material under tile shower floors. He says that although Wedi board adds an extra $300 to the cost of creating a 3-foot-by-5-foot shower, it’s worth it. “Someone’s wall or window leaking ... that’s the worst public relations,” Crossman says. “That $300 ... is a must to protect your financial well-being and your reputation.”

Mark Elia, owner of Mark of Excellence, in West Long Branch, N.J., says 24-inch-by-36-inch windows in showers are common in post–World War II houses and that some homeowners choose to close them off. In such cases, he might recommend a circle-top window above the shower to admit natural light.

If a homeowner opts to keep the opening, Elia specifies a vinyl window — wood will eventually rot — and uses a silicone sealant around the opening. For operating windows, he uses stainless steel hinges and hardware, which hold up better to moisture. See more waterproofing images at Remodeling Online.

—Nina Patel, senior editor, REMODELING.