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Unread 11-21-2002, 10:30 AM   #1
flatfloor
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Greenboard Shower info

This from Newsday our local paper. I posted here first for comments, maybe it should go in the Liberry? I'm also going to invite Gary to visit.

It's a Scary Shower Scene
Gary Dymski

November 21, 2002

My daughter Melissa emerged from our steam-filled main bathroom. "Dad, there's something not right in the shower," she said.

What usually follows such a pronouncement is a complaint about the lack of hot water or the shrinking household supply of floral-scented, herbal-injected, honey-colored, overpriced shampoo.

This time, however, the complaint was worth hearing - our shower wall had collapsed. My daughter was convinced our house, built in 1997, was crumbling before her very eyes. "I just put my hand on the wall while getting out of the shower, and the wall just gave way," she explained, looking at the large indentation behind the ceramic tile. "What's the deal?"

The deal is that the shower wall in our main bathroom must be completely replaced. When the tile in our bathrooms was installed, it was installed against greenboard. Eventually, I will have to rebuild three shower walls, and if I go with tile again, you can bet I won't be using greenboard, a water-resistant gypsum wallboard, as a backer board.

Several upcoming columns will deal with this project, from the tearing out of the existing moldy, mildewy shower wall to complete installation of a new wall, either of tile or a one-piece acrylic.

But before we get to the project, my question is: Why are builders and contractors allowed to use greenboard or wallboard as a backer for ceramic tile? My experience is that wallboard fails repeatedly as a substrate for ceramic tile in wet areas. So why aren't newer materials, like water-friendly cement backer boards, required by local building departments for such installations?

As a resident of Brookhaven, I posed this question to Tom Moore, a town building inspector. According to Moore, town building regulations often call for the absolute minimum standards. And in the case of ceramic tile on water-bearing walls, regular wallboard will do in Brook- haven. After a series of questions about my builder and the age of the home, Moore suggested my collapsed wall was the result of installation failure rather than product failure. "If a tile job is done correctly on wallboard, it can last 50 years and never come down," he said.

Robert Wessel, assistant executive director of the Gypsum Association in Washington, D.C., agrees. "Water-resistant gypsum backer board is specifically designed [by their manufacturers] to be used as a substrate for plastic or ceramic tile," Wessel says.

Why did the wall fail then, not after 50 years but after about five? Wessel blames installation and maintenance. "Under the newest installation recommendations," Wessel said, "wallboard is supposed to get a skimcoat of ceramic tile adhesive before the tile is installed." Once the adhesive dries to create a more water-resistant substrate, then the tile can be installed. Wessel said many contractors skip this newer recommendation. "Not knowing how they built your shower wall, the contractor could have missed this step," he says. "Also, the grout and sealants in this wall must be properly maintained. Once water gets between the grout and behind the sealant, the substrate can fail."

That's precisely the problem with using gypsum boards, says Justin Woelfel, director of training and education for the National Tile Contractors Association in Jackson, Miss. "With gypsum board, there's no room for error," Woelfel says. If even a small amount of water gets behind the tile, the substrate can fail.

Woelfel says that members of the National Tile Contractors Association are specifically instructed not to use gypsum board as a backer for tile in extremely wet areas. "The reason builders use wallboard is that it is cheaper and easier to install," Woelfel says. "Some builders don't want to pay the price to do it right the first time." (Cement backer board costs more, is heavier and often more labor-intensive because it should be cut with a reciprocating saw. Gypsum is lighter and can be scored with a utility knife.)

Woelfel said there are more than a dozen newer substrates that can be used, many of which meet the American National Standards Institute guidelines for ceramic tile installation, which his association follows. Many of these newer backer boards are cement-based panels with names like Wonderboard and Durock.

Cement backer boards mimic the traditional way of installing ceramic tile, which was to create a wall or subfloor of concrete held together by metal lathe (called a "mud job" in the trade). These backer boards are cement panes wrapped in fiberglass mesh, and when tile is applied to them using thinset mortar the result is almost as good as a mud job.

In fact, the National Gypsum Co., a major wallboard manufacturer, has recognized the success of cement boards. It now makes its own cement board, PermaBase, to be used as a substrate on wet walls. The company also says greenboard should not be used on walls that come into continual contact with water.

So, if the new shower walls in the Dymski household are lined with ceramic tile, it's a lock that cement backer board will be the substrate.

"I think you're on the right track," Woelfel said.

First, there's a little matter of tearing down the rest of those existing walls.

Although he cannot always respond personally, Gary Dymski welcomes letters. Write to him at Newsday Home Work, 235 Pinelawn Rd., Melville, NY 11747-4250 or e-mail gary.dymski@newsday.com. Include your community of residence.
Copyright © 2002, Newsday, Inc.


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