It starts out as some loose caulking where the tile meets the bath tub. One tile seems a bit loose. It falls out. Then another followed by another. Before you know it an entire section of tile is out. The dry wall behind it is moist and likely molding. You have reached the point of no return. Your shower is going to have to be retiled. You can call in a professional or you can do it yourself.
Before you begin the tear out of the old tile, remove the handles and covers on the plumbing fixtures. Tearing out the old tile and backer boards should be done with some care. Falling debris, such tile and nails, can scratch the surface of the bath tub. Cover the tub before you begin. Pre-cut the edge right above the tile line in a straight line before you begin the tear out so you can match the new backer board tightly to the existing wall surface with a nice, neat edge. An oscillating or rotary saw is a great tool for making that cut.
Once the tear out is complete you are ready to install the new backer board. Most construction in the 1990’s and earlier used a material commonly called “green board” for backing around moist areas to be tiled such as showers and tubes. It gets its name from its light green color. The idea was that it was moisture resistant dry wall. While it will resist moisture better that ordinary dry wall, it is certainly not water proof. Many building codes no longer permit its use for showers. You do not want to use that product.
Fiber cement board is now the most common product used. It is completely resistant to moisture. There are many products available. Wonder board and Hardiebacker are two that are widely available in home improvement stores. The most common size is 3’ x5’ sheets. For shower walls you what to use ½” thick product. While neither product will deteriorate from moisture, Hardiebacker is more resistant to penetration from moisture. It is also much easier to cut.
Wonder Board and Hardiebacker
Before you install the backer board make sure the framing runs in a straight line across studs. Many times the framing in tight areas will need to be shimmed in places to create a smooth, flat surface for the tile. Also, outside walls that are insulated should not have a vapor barrier (plastic sheeting) installed between the backer board and frame as is done for drywall in a room. Finally, make note of electrical wiring and plumbing locations. You do not want to drive a nail or screw into either as you are installing the backer board.
Install the backer board starting from the bottom up. The board can be nailed with galvanized roofing nails or screwed with corrosion resistant screws: each 1 ¼” long. Nail or screw every 8.” Keep fasteners ½” away from the edge of the material and 2” away from corners.
One you have completed the installation of the backer boards you need to tape all the joints using 2” wide alkali resistant fiber glass tape and modified thin set mortar. The tape will help disperse any movements of the substrate. This will decrease the likelihood of the tile popping lose or cracking along the seams.
You shower is now ready to tile. For fiber cement backer board you need to use a modified thin set mortar to set the tile. You can typically buy these powder mixes in white or gray. Choose white for light color tile and grout and gray for darker tiles and grouts.
Tips for Tiling a Shower
The methods used to tile a shower a similar to that of other surfaces. However, there are a few differences to note. Start at the bottom and work up. Make sure your first row is level. Don’t assume the tub is. Tiles on a wall may want to slide down after they are placed. Use spacers, particularly between the tube and the first row, to prevent this from happening. You can save yourself a lot of rework on the finished wall above the shower if you plan for the last row of tile to slightly over lap onto the finished drywall. Plan that when you make the cut before removing the old drywall.
When you grout, do not grout between the tub and the tile or in the corners. Grout will not stay in place in those locations. They should be caulked. Many tile suppliers sell caulk that matches the grout.
Caulking can be messy. One trick to minimizing the mess is to use masking tape along both edges where you are going to caulk. Once you have pressed the bead of caulk in place remove the tape. You will have a nice, neat edge and not have caulk smeared on the surface of the tile and tub.