Why are some of my tiles uneven?
The term lipping relates to situations where, for one reason or another, the edge of one tile protrudes above its neighbour
Lippage 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.
Australian Standard AS 3958.1 – 2007 recommendations for tile finish and joints are as follows:
“When measured with a straightedge, the finished surface of the tiling should be flat and true to within a tolerance of ±4 mm in 2 metres from the required plane. The lippage between two adjacent tiles should not exceed 2 mm. In the case of tiles where the surface has been ground flat, the lippage should not exceed 1.5 mm, and for joint widths of 3.0 mm or less the lippage should not exceed 1.0 mm.”
Note that in AS 3958 there is no mention of rectified tiles where it is common practice to have narrower grout joints. Therefore it is commonly agreed to treat these tiles similar to ground flat tiles when it comes to allowed lippage.