Rescuing a Badly Damaged Shower

This ceramic tile shower is on life support. It needs an overhaul to prevent long-term structural damage to the house.
This ceramic tile shower is on life support. It needs an overhaul to prevent long-term structural damage to the house. (By Diana Cordero -- Tribune Media Services)

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By Tim Carter
Saturday, October 11, 2008

Q. DEAR TIM: My ceramic tile shower has severe water damage. I was cleaning the shower when the tile caved in, creating a hole in the wall. How can I install tile in the shower so this will never happen again? Is this a job I can do myself? What are the steps to get long-lasting results? -- Diana C., Norcross, Ga.

A. DEAR DIANA: Your situation reminds me of a nightmare I went through many years ago. Water-resistant drywall was just coming into the marketplace, and it was being touted as a miracle product. You could easily install it and apply ceramic tile right over it. The core of the drywall was treated with silicone so it wouldn't fall apart.

Six years later, while cleaning the shower, I pushed my ceramic tile into the wall cavity. Other tiles near the hole fell off the wall like paint chips on an old house. It was a mess.

If you were to visit a home in your area that was built before the 1940s, you would probably find the ceramic tile showers in good shape. That's because back then ceramic tile was installed directly on top of concrete. The tile setters used to apply cement plaster on wire mesh that was nailed to the wall studs. They would then install the ceramic tile the next day using a pure Portland cement paste. This putty bonded to the uncured concrete mixture on the wall, making a permanent bond.

Concrete is waterproof. Once concrete cures, water will not cause it to rot or turn to powder. Your tile shower failed because the gypsum board turned to mush after years of water seeping through the grout joints. Tens of thousands of homeowners have experienced the same.

You can tackle this job if you can follow directions. If you want to repair your shower just one time, you need to strip all the ceramic tile down, as well as the rotten drywall. If there is any wood rot, you may have to install new wood wall studs. Take the time to install the studs perfectly plumb. This will make the tile installation go that much more quickly. This is also a great time to make sure the tub or shower base is level from front to back and side to side. Use galvanized metal shims cut from metal ductwork for this task. Wood shims can rot over time or compress from the weight of the tub.

I prefer to install a one-piece vapor barrier on the wall studs before installing the ceramic tile backer board. It is important for this plastic to lap over the tub or shower-base flange. This membrane protects the wood wall studs from getting wet. Be sure you tuck the vapor barrier membrane into the corners tightly as you install it.

The wall studs are then covered with a cementitious or totally waterproof gypsum-based backer board. These products are often the same thickness as regular drywall. They are often easy to handle and cut. Follow the instructions as to the proper fasteners to use. Some allow you to use hot-dipped galvanized nails and others require screws.

I prefer to hold these backer boards up from the tub or shower deck about 3/16 inch. I do the same at corners and horizontal seams. After the backerboard is installed, I vacuum up any dust and caulk the gaps with pure silicone caulk. Some written instructions will also tell you to tape the joints with a special tape and thinset mortar. If you do this, you need to be really careful about not creating a hump at any of the corners or horizontal seams. If there is a hump in the wall, the ceramic tile will rock back and forth at these high spots.

The first row of tile must be perfectly level. I achieve this by installing the second row of tile first. Nail a straight board to the wall that acts as a ledge for the tile to rest on as subsequent rows of tile are added. Once the mastic or thinset is firm, remove the boards and install the missing row of tile just above the tub or shower.

Tim Carter can be contacted via his Web site, http://www.askthebuilder.com/printer_Submit_Question.shtml.

Copyright 2008 Tribune Media Services


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