Lippage: An Introduction

Lippage is defined as “A condition where one edge of a tile is higher than an adjacent tile, giving the finished surface an uneven appearance”.

Excessive lippage on floor could be hazardous in environments where the risk of tripping needs to be as low as possible. For example, people working in food preparation area often carry sharp knives, or have to handle containers of scalding liquids. It is particularly important that floors be as flat as possible to reduce the risk of tripping.

The lippage of polished porcelain tiles may not be the tiles fault, or the tiler who installed them, it may be a combination of a few elements. When assessing the degree of lippage inherent within a tiling installation the following factors must be considered:

• Surface flatness of the substrate
• Curvature or warpage of the tiles
• Pattern in which the tiles are installed
• Workmanship

AS 3958.1-2007, Ceramic tiles, Part 1: Guide to The Installation of Ceramic Tiles states that:
“The lippage between two adjacent tiles should not exceed 2 mm. In the case of tiles where the surface has been ground flat for example polished tiles, the lippage should not exceed 1.5mm, and for joint widths of 3.0mm or less the lippage should not exceed 1.0mm”, noting that  “This condition is inherent in all installation methods and may also be unavoidable due to the tile tolerances. Lippage may also be unavoidable where tiles larger than 150 x 150 mm are graded to a waste outlet, unless transverse cuts are incorporated”.

Many people are unaware that polished porcelain tiles can curve as much as 0.5% the length of the tile. For instance if you have a 600 x 600 mm polished porcelain tile, the surface can warp up to 3 mm by the Australian and International Standards.

In these cases it may be impossible to reduce the amount of lippage of polished porcelain tiles to less than 1 mm as required by AS 3958.1-2007. These factors need to be considered when assessing the unsatisfactory tiling appearance.

Sources:
– AS 3958.1-2007, Ceramic tiles, Part 1: Guide to the installation of ceramic tiles
– Safe Environment (www.safeenvironment.com.au)