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Full bathroom remodel, part 4: building your shower stall

Jim Mallery | Improvement Center Columnist | July 18, 2012

shower subfloor feature

Fourth of an eight-part series on bathroom remodeling

In part 3 of this bathroom remodel series, we covered tips for making necessary plumbing alterations. Get ready to tackle building your custom tile shower.

"Make it right, watertight" and "Let it seep, and you will weep" should be your mottoes. Your shower pan and stall must be impervious: You simply cannot let water get to the wood.

If you have a standard-sized stall, you can buy an acrylic or fiberglass shower pan, though you lose the aesthetics of an all-tile shower. If you want some kind of mosaic floor, you can buy a shower pan designed to hold mortar and tiles. Or you can build your own pan.

Building a shower pan

shower stripped to studs

Starting from scratch, the old shower is ripped out down to bare studs. With the plumbing done, the next step will be to put in a new piece of subfloor and blocking up the sides of the walls to act as backing for the vinyl liner.

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building a shower pan

Ready to start building the custom shower pan.

 

Keep this key concept in mind: Moisture travels through grout and mortar, which are not waterproof. Water must be stopped by an impervious layer before it gets to the wood.

As shown as shown in this example from Oatey, the pan design is not complex, though it can be tricky to get right. Atop the plywood subfloor, you build a mortar base, sloping it at a rate of at least a quarter-inch per foot to the base of the drain. You cover the base with a vinyl membrane that runs up the wall a few inches. The membrane goes into the drain fixture designed specially for tile floors. Screw the top of the drain into the plate to the depth of the finished floor. On top of the membrane put an inch or more of mortar, then thinset and tile.

The Home Depot and Lowe's have the membrane and special drain. Many tile stores also carry them.

Pan-building guidance

how to install a shower subfloor

The new subfloor and backing between the studs for the vinyl liner. The threshold in the foreground is made with a 2-by-6.

 

shower drain first layer

The first layer of mortar is in place, creating a ¼-inch per foot slope to the drain. The drain is covered with duct tape to keep mortar out. Note that insulation, absent behind the old shower stall, has been added to the outside walls.

 

drain parts for shower stall 

Here are the pieces to the drain. The liner will go over the black plate and into the drain. The locking ring (center) fits over the four bolts and tightens down to secure the liner. The upper section of the drain (left) screws into the locking ring to match the height of the final tile floor.

 

drain locking ring

The locking ring is in place over the vinyl liner, ready to be tightened down. Moisture will travel to the drain through the weep holes in the top of the ring.

 

pebble fill for shower drain

With the upper section in place, pea gravel covers the weep holes to prevent them from being plugged by the final layer of mortar.

 

Threshold: A 4-by-6 chunk of lumber with backerboard on the sides and top makes a good threshold. Of course, you need to slope it toward the shower. When the tile is added, it will be about 6 ½-inches wide -- a ¼-inch slope is fine.

shower pan ready for mortar

Shower floor ready for mortar and tiles

 

Mortar 1: You can use a standard mortar mix to build up the base in the pan, but special mixes called "dry set" make the job much easier. The consistency is more like wet sand at the beach. You can usually get this mix at a tile store.

Tile: You can find a good selection of pebble or mosaic tiles for your floor at Lowe's and The Home Depot, probably spending a couple dollars per square foot less than at your specialty tile store.

completed shower stall floor

Shower floor is finished, but the marble still needs grout.

 

Mortar 2: Your floor pebbles or mosaic are glued to a mesh backing. If your thinset is too thin, it will ooze through the mesh into the grout space. Make your thinset a little stiffer than usual, and be careful not to push too hard on the tile. If you sink a mosaic piece too deep into the thinset, pull it out, hose it off and start over.

Backerboard advice

backerboard installed in new shower

The DenShield backerboard is in place, with the joints sealed and taped. A black plastic cover protects the shower valve; the plastic box ($40), designed to hold thinset and tile, provides a shower shelf.

 

You will line your walls with ½-inch backerboard. Some backerboards, such as James Hardie's HardieBacker, are not impervious and require a layer of roofing felt or plastic against the studs. Others, such as wedi products or DensShield from Georgia-Pacific, are designed to be waterproof and do not need the felt or plastic -- though you do have to caulk the seams.

The wedi company manufactures a complete system for building a shower. It is high quality and relatively easy to work with, but appears incredibly expensive at quadruple the cost of HardieBacker. DensShield is only slightly more expensive than HardieBacker but seems easier to install.

The wall's water barrier -- either the roofing felt/plastic or the impervious backerboard -- should overlap the vinyl membrane that extends up the wall from the pan so that any water will flow onto the top of the membrane.

Whichever product you use, follow its installation instructions carefully.

You need to be meticulous in building a custom shower pan, but it is much cheaper than using preformed pans and lets you create a shower to a non-standard measurement.

Tile-laying tips

shower shelf no grout

The tile without grout can look pretty bad.

 

completed tiled shower shelf

Grout smooths out the harsh, unfinished tiles.

 

new DIY tiled shower stall

The tiling and grouting is completed, but door still is not installed.

 

You don't want your bathroom remodeling to look amateurish. If you are a total tile newbie, the vast expanse of tile in this project could be overwhelming. If you are anxious about the finished look, you might consider a bathroom remodel contractor.

If you decide to do the tiling yourself, here are a few tips:

  1. Buy a tile (wet) saw. Renting one for the duration of this project could cost more than buying one.
  2. Know your tile. Ceramic tile is only colored on the surface; a cut edge should not be exposed. However, you may be able to buy matching trim pieces. Porcelain tile is colored throughout, and a cut edge can be exposed -- though even with polishing, it may not look like the factory surface. Stone tile can be cut, and with some patience and a lot of sandpaper it can be polished.
  3. Be patient. Level your tiles and make frequent use of a straight edge. If a tile is not set level or straight, pull it out and start over. Be careful not to inadvertently put your weight on a tile that is already in place while you work on another. It tends to knock the good tile out of whack.

Mosaic tiles aren't as easy to install as the television pros make it look. See the accompanying story on the trials and tribulations of installing mosaics.

Next, part 5: laying a heated tile floor

About the Author

Jim Mallery, a semi-retired journalist and onetime registered contractor, has extensive experience remodeling, repairing and rebuilding homes.