Why are some of my tiles uneven?
​Tile Lippage

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.​

Causes of Tile Lippage

Lipping can be caused by:

• Poor or uneven preparation of the substrate.
  • In many instances tiles are fixed using thin-bed adhesives and fixing techniques. In this instance the prepared substrate should not deviate by more than 4 mm, when a two metre straightedge is placed on the surface. If a gap is larger than 4 mm appears, it will be necessary to adopt a thick-bed fixing technique.
• The background may not be clean.
  • All surfaces should be cleaned before adhesive is applied, as particles of grit trapped under a tile will induce lipping.
• Protruding nails or screws.
  • Ensure that nail or screw heads are flush with the surface of the substrate.
• Excessive curvature of the tile.
  • The Australian Standards allow for a degree of curvature in finished products. This may pose a problem, particularly when a brick-fashion rectangular tiling design is adopted, as curvature will occur in the centre, thus the ends of the adjacent tiles will be lower than the centre. Careful application of adhesive is required to overcome this potential problem, which will be exacerbated if the substrate is not flat. Alternatively, lay tiles in a stackbond pattern rather than brickbond (or at a minimum in a ¼ / ¾ pattern).

General

Lipping tiles are unsightly, particularly if they appear throughout the installed tiles. They may also create a trip hazard.

The best way to avoid lipping is to ensure that substrates are flat and are prepared in accordance with the prevailing standards and that they are clean and free of debris before tiling commences. Importantly, the adhesive must be applied evenly using an appropriate notched trowel, using the chosen thin or thick-bed fixing technique.

Slightly uneven backgrounds can be overcome by careful application of adhesive, which should be evenly applied to the substrate and added to the back of the tile in the appropriate place.

Alternatively, the substrate can be screeded to make it flat.

A number of suppliers of tiling tools and allied products market tile levelling systems which are designed to ensure that the entire floor is completely flat. Spacers are installed which effectively eliminate the possibility of lipping in ceramic and natural stone wall and floor tiles of various thicknesses, including 3 mm.

Perceived or apparent lippage is a condition where the tile installation meets the standards and does not have excessive lippage, but appears to have excessive lippage. This can be caused by natural or manufactured lighting emanating from an angle that accentuates the lippage by creating a shaded edge. Highly reflective surfaces can compound this condition making it appear to be excessive lippage when it isn’t.

Timber Tiles/Wooden Plank Tiles​

Timber-look ceramic tiles can be as aesthetically pleasing as genuine wooden floors, with added benefits that include greater durability, water resistance and lower maintenance. It is, however, essential to follow the correct installation procedures.

There are permissible manufacturing tolerances for ceramic tiles, and the tiles may have permissible surface flatness irregularities. For example, the tile surface may have a slight curvature. If this is not taken into consideration when planning the installation, there is a risk of tile ‘lipping.

Many timber-look tiles are the length of wooden planks where the length of at least one edge is equal to or greater than 600 mm. Laying of these tiles in a brick or running bond pattern should be carefully considered because of potential lipping caused by the curvature of the tiles. A maximum offset of 25 to 30 per cent is recommended.

Rectangular Tiles (including 300 x 600 mm tiles

The information above also applies to rectangular tiles laid in a brick or running bond pattern. To minimise the risk of lipping, it is recommended that when installing 300 x 600 mm size product tiles in a ‘running bond’ pattern, the longest side should be staggered in relation to the length of the piece next to it by no more than 100 – 150 mm. This equates to a maximum offset of 25 per cent. (¼.)

Credit: Australian Tile Council