The flatness of your subfloor is the foundation of a professional tile installation. If the floor has high spots or depressions, the tile will not lay flat, leading to 'lippage' where one tile edge sits higher than the adjacent one. This is not only a tripping hazard but also a major cosmetic defect that makes the tile look poorly installed. For large-format tiles, which are increasingly popular, the tolerance for flatness is even more strict, as these tiles do not flex and are prone to cracking if bridged over a low spot. Before you begin your tile project, use a long level or a straight edge to check the flatness of your subfloor in multiple directions. If the floor is out of tolerance, you must correct it before installing the tile. This can be done by sanding down high spots in wood or concrete, or by applying a self-leveling underlayment to fill depressions. Do not assume your tile contractor can 'float' out a wavy floor with just thin-set, as this can lead to bond failure if the mortar bed becomes too thick.
Key considerations
- floor flatness for tile
- leveling subfloor
- tile lippage issues
- Subfloor
- Leveling
- Straight Edge