Installing an attractive, matching tile shelf in your shower will add space to your project. Building the tile corner shelf into the wall itself as you tile the rest of the shower's surface is the simplest and most durable way to add this feature. By interlocking the tile shelf with the shower wall as you tile, your corner shelf will be sturdy, waterproof and permanent.
Prepare the base for your shelf. Install your wall tile until you reach the height that you want the tile corner shelf to be. The top row of tiles will serve as the resting base for your self.
Prepare the thinset mortar according to manufacturer's directions if it is not premixed. Apply a small amount of thinset to the backer board above the last row of tiles. Place the tile corner shelf finished side up on the last row of tiles so that it is backed tightly into the corner. Apply a small amount of thinset in between the corner shelf and the last row of tiles for extra hold.
Continue tiling the shower wall. The shelf makes the row of tiles uneven. To even them out again, cut the tiles that will sit on top of the corner shelf as you set the next row of tiles. Work from left to right; when you get to the uneven shelf area of the row, cut each tile individually with the electric tile cutter before placing it in line. Measure the area where the shelf interferes with the new row's tile and mark it with the speed square and pencil before cutting.
Finish the corner shelf area. When grouting the rest of the wall with grout and the trowel, fill in the areas between the cut tile and the corner tile shelf. While the grout is still damp, use a sponge and warm water to clean off any excess grout from the tile's surface.
If you are tiling your shower with a tile 12 inches across or more, then cutting it in half and sanding the edges is one solution for your corner shelf. To do this use the electric tile cutter and cut the tile from one corner to its opposite corner. Then use the sanding stone to get a smooth, safe finish. Keep in mind that pre-made corner tiles are inexpensive and will often have a nice curved edge that looks better than a diagonal cut once installed. Ensure that your corner shelf is level so it doesn't disrupt the ensuing rows of tile.
Be aware of where your hands are placed when using the electric tile saw. Use protective safety eyewear every time you operate the electric tile saw.