"Buttering a tile," more formally known as back buttering, is a fundamental technique in tiling where you apply adhesive directly to the back of the tile before setting it. This ensures maximum contact and a strong bond between the tile and the surface it's being laid on.
Understanding Back Buttering
Back buttering involves spreading a thin, even layer of tile adhesive (often thinset mortar) across the entire back surface of a tile. While adhesive is typically also spread on the floor or wall (the substrate) using a notched trowel, back buttering acts as a crucial supplementary step to guarantee full coverage, especially in challenging situations.
The Technique for Effective Back Buttering
Based on best practices in tiling, achieving an effective and quick back butter requires specific handling of the adhesive and trowel.
- Spread with a Notched Trowel: To start, use a 4mm notched trowel to spread the adhesive evenly across the back of the tile. The notched side helps distribute the adhesive and create small ridges.
- Flatten the Ribs: After spreading, then flatten the ribs with a flat side of the trowel. This step is key; dragging the flat edge back over the notched adhesive layer pushes the mortar into any textures or low spots on the tile's back, eliminates air voids within the adhesive ridges, and ensures that the entire back surface has adhesive coverage.
This two-step process ensures both an even distribution and proper contact with the tile's back profile.
When is Back Buttering Important?
Back buttering is a technique that enhances the quality and durability of your tile installation. It is especially important in specific scenarios to prevent potential issues and ensure robust adhesion across the entire tile.
- For tiles which are slightly bowed. Back buttering helps fill the concave back of the tile.
- For tiles that are uncalibrated, meaning they have slight variations in thickness or size.
- Where the back of the tile is uneven or has a deep relief pattern.
- For large format tiles (often considered tiles with at least one edge 15 inches or longer), as they are more prone to bowing and require maximum coverage for stability.
- When laying tiles over potentially uneven substrates, back buttering helps achieve better contact.
Why Back Butter Your Tiles?
The primary goal of back buttering is to achieve as close to 100% adhesive coverage on the back of the tile as possible. Voids under tiles can lead to several problems, including:
- Weak Spots: Areas without adhesive are susceptible to cracking if weight or impact is applied.
- Grout Failure: Voids can cause grout lines to crack or fail prematurely.
- Water Penetration: In wet areas, voids can trap moisture, potentially leading to mold or substrate damage over time.
Properly back buttering helps create a solid, monolithic layer of adhesive, ensuring the longevity and structural integrity of your tiled surface.
| Step | Tool Used | Action | Benefit |
|---|---|---|---|
| Spread Adhesive | 4mm Notched Trowel | Apply adhesive, create ridges | Even distribution, initial coverage |
| Flatten Adhesive Ribs | Flat Side of Trowel | Smooth over ridges, fill voids, push in | Full contact with tile back, eliminate air |
