For installing 12×24 floor tiles, the recommended trowel size is a 1/2-inch square-notch trowel. This choice ensures adequate mortar coverage, which is critical for large-format tiles to prevent voids, lippage, and ensure proper adhesion. Here’s a breakdown of the reasoning:
Tile Size and Mortar Coverage:
- Larger tiles like 12×24 require more mortar to support their weight and span. A 1/2-inch notch provides sufficient mortar volume to achieve the recommended 80-95% coverage on the tile’s back.
Substrate Considerations:
- If the substrate (floor) has minor imperfections, a deeper notch helps compensate for unevenness, reducing the risk of tiles not adhering properly.
Mortar Type:
- Use a medium-bed mortar designed for large tiles. It resists sagging and pairs well with a 1/2-inch trowel for optimal application.
Professional Guidelines:
- The Tile Council of North America (TCNA) suggests a 1/2-inch trowel for tiles over 16 inches on one side. While 12×24 tiles have one shorter side (12″), the 24″ length classifies them as large-format, warranting the larger notch.
Installation Technique:
- Hold the trowel at a 45-degree angle to create uniform ridges. After setting the tile, press firmly and twist slightly to spread the mortar evenly.
Note: Always check the tile and mortar manufacturer’s specifications for any unique requirements. If the substrate is exceptionally flat, some professionals might use a 3/8-inch notch, but 1/2-inch is the standard recommendation for reliability.
