Floating a Buttering
Floating and Buttering in Tile Adhesion: The Professional Standard
1. Definition of Terms
In tiling practice, the terms floating and buttering are commonly used to describe methods of applying tile adhesive.
Refers to the process of applying adhesive onto the substrate (wall or floor). The adhesive is first spread with the smooth side of the notched trowel to create a continuous layer, and then combed with the notched side to form ridges in a uniform direction.
Means applying a thin, continuous layer of adhesive onto the back of the tile. The purpose is to improve adhesion and ensure full contact between the substrate and the tile.
The combination of these two methods – known as floating–buttering – represents the standard approach, especially when working with large-format tiles.
2. Issues and Challenges
Incorrect application of tile adhesive is one of the most common causes of tile defects and subsequent claims. Typical problems include:
- Voids: The tile is not fully supported across its surface, leading to stress concentration and cracking under load.
- Moisture Retention: Water penetrating unfilled areas leads to adhesive degradation and frost damage in exterior settings.
- Insufficient Coverage: EN 12004 requires min. 80% coverage for interiors and 90–100% for exteriors or large formats.
If ridges are applied crosswise or in arcs, air becomes trapped when the tile is pressed. These resulting voids pose a high risk of future structural failure.
3. Correct Technological Procedure
- Substrate Preparation: Surfaces must be solid, level, and dust-free. Absorbent substrates must be primed.
- Applying to Substrate (Floating): Create ridges with a notched trowel in one uniform direction (vertical or horizontal). Choose notch size (4–12 mm) based on the tile format.
- Applying to Tile (Buttering): Spread a thin, continuous layer of adhesive on the back of the tile using the smooth side of the trowel.
- Combining Layers (Floating–Buttering): Place the tile and move it back and forth slightly. This collapses the ridges and fills all air gaps.
- Verification: Periodically remove a tile to check coverage. Aim for a continuous layer without voids.
4. Conclusion and Expert Witness Perspective
Proper application of floating and buttering methods is a key prerequisite for long-lasting tiling systems. As a professional expert witness, I conclude that strict technological discipline must be maintained at all times.
TECHNOLOGICAL DISCIPLINE FIRST
The floating–buttering method and uniform ridge direction are mandatory. Failure to comply can be legally evaluated as a technological fault of the contractor.