Installing tile in a shower niche with trim is a rewarding project that transforms a functional storage area into a design highlight. This process requires precision, the right materials, and a methodical approach to ensure waterproofing and a seamless finish. By focusing on both the structure of the niche and the aesthetic of the trim, you can achieve a professional look that enhances the entire shower experience.
Planning and Material Selection
Before the first cut is made, careful planning is essential to the success of your project. You must determine the exact dimensions of the niche and the style of the trim to ensure visual harmony with the rest of the shower. Selecting materials that complement each other in color and texture creates a cohesive look that elevates the space.
The key materials for this project include:

- Tile for the back and sides of the niche.
- Trim pieces specifically designed for shower niches, often bullnose or pencil edge profiles.
- High-quality thinset mortar suitable for wet areas.
- Waterproofing membrane, such as a cementitious or liquid-applied type.
- Flexible grout that can withstand moisture and movement.
Preparing the Niche Surface
A stable and clean substrate is the foundation for a durable tile installation. If the niche is newly constructed, ensure the surface is smooth and free of debris. For existing niches, you must inspect for any loose material or damage and repair as necessary to provide a solid backing.
Next, apply a waterproofing membrane to the interior walls of the niche. This critical step prevents moisture from penetrating behind the tile, which could lead to mold or structural damage. Follow the manufacturer’s instructions for application, ensuring complete coverage and allowing adequate drying time before proceeding.
Layout and Dry Fitting
Dry fitting the tiles and trim pieces is a step that saves time and prevents costly mistakes. Begin by laying out the tiles within the niche without adhesive to visualize the pattern and confirm that cuts are necessary. This process helps you adjust the starting point to ensure symmetrical edges and balanced grout lines.

Use a pencil to mark the center line of the niche both horizontally and vertically. These guidelines will help you maintain straight rows and ensure the trim aligns perfectly with the center of the niche front. Consistent layout is the key to a polished and professional finish.
Setting the Tile and Trim
With the layout confirmed, you can begin applying thinset mortar to the back of the first tile. Press the tile firmly into the niche, aligning it with your center lines and using tile spacers to maintain uniform grout joints. Work slowly and deliberately to avoid shifting the tile once it is in place.
For the trim pieces, apply thinset to the back and press them into position along the edges of the niche. The trim should overhang the tile slightly to create a finished, integrated look. Use a rubber mallet to gently tap the trim into place, ensuring it is level with the surface of the main tiles.
Grouting and Finishing
Once the mortar has cured, it is time to apply grout to lock the tiles and trim together. Choose a flexible grout that can handle the humidity of the shower environment without cracking. Use a rubber float to press the grout into the joints, holding the float at a 45-degree angle to remove excess material.
After the grout has set, clean the surface thoroughly with a damp sponge to remove the haze. A final inspection will reveal whether any joints need to be touched up. Proper sealing of the grout lines is highly recommended to protect against water infiltration and stains, ensuring the longevity of your work.