You will need: Thinset, 2 buckets, wedges, duct tape, trowel or putty knife, level, sponge, stapler, and moisture barrier paper or red guard.
Step 1: First, you must frame your opening to the size of the unit you have purchased. Available standard sizes for your rough opening will be 14-1/2" wide X 12-3/4" high for the small unit or 14-1/2" wide X 18-1/2" high for the larger, two shelf option. Test that your recessed wall niche fits into opening prior to completing the installation instructions.
Step 2: Install your moisture barrier paper to the wall area surrounding the framed opening. Staple excess paper into box about 1".
Step 3: Install backer-board over the paper. It is unnecessary to install backer-board inside the framed opening.
Step 4: Paint on Red Guard water-proofing and let dry. Apply additional coat if you have suspect areas without enough coverage. Red Guard is excessive for this application, but will insure you are safe from future moisture damage. Minimum protection would be to use a moisture barrier paper folded into opening, covering the entire inside area. The proper technique for installing paper is to start at the bottom and overlap as you proceed upward. Paper should be installed prior to installing backer-board to the walls.
Step 5: Mix thinset mortar and place liberal amounts onto the inside bottom of framed area and top and sides of the wall edge along the framed area.
Step 6: Also apply a liberal amount of thinset to the top of the Niche, and a thin coat to the bottom and on the backside of all framed edges.
Step 7: Place the bottom of Niche into the opening first, about 1 ½". Then gently push down until top of Niche will fit into the opening.
Step 8: Slide Niche into opening pushing the left and right sides in together until the gap between the wall and frame is about 3/16" thick. Do not leave unit unattended until final step of duct tape.
Step 9: Use the level to insure shelves will drain towards you. Place wedge(s) if needed behind the frame at the top or bottom, and push in the opposite end tightly. Check for drainage using the level. Clean excess thinset around the edges and at bottom. The shelf needs very little drainage, but it is important to avoid drainage back into the unit.
Step 10: Clean excess thinset mortar from edges of the unit where it meets the wall.
Step 11: Use duct tape to hold unit in place for 4 hours. Use paper (or something similar) to protect Niche from duct tape adhesive. Once dry, remove tape. Now you can cut and set tile within and around your Recessed Shower Wall Niche.
TIP: You can install tile to the back of your Niche before installing it into the wall. This is easier than once it is installed. Be sure you are not trying to follow the pattern of the wall tile when using this tip.
Here is an image of a RAFI Creations' custom recessed shower niche completed.