Dealing with Complaints about Warped Tiles

This is my second article on warpage in tiles, mostly because certain key changes have occured in the international standards. More on that later.

Due to the process of firing a natural product like a ceramic tile, it is expected that every tile is not going to be absolutely perfect. Warping of the tile itself is one of the more common issues in manufacturing. This is why there is an International Standard set down to specify the acceptable tolerances for warping in tiles. If a delivery includes tiles that seem to be warped, the tiler would generally decide not to lay these ones. Remember that tiles simply cannot warp after being laid. They are completely rigid, the may crack or lift but the don't bend!

Any warping in a ceramic tile will happen in the factory during manufacture. It is important to realize that a certain amount of warping across a tile is acceptable under the standards. The calculation for acceptable warpage is related to the size of the tile and the degree of warp across the length of the tile. Although all Tiles are graded within the set tolerances, sometimes poorly graded tiles can slip through and be packed as first grade.

Recently, a major revision was made to an important standard under the jurisdiction of ISO/TC 189, ISO 13006 which establishes the international specifications for ceramic tile.
The ISO 13006 International Standards specify an allowable percentage of variation. Previously the flatness (warping or bending) of the tile allowable was 0.5% of the diagonal length of the tile. This allowed for a possible bend of up to 3mm bend on a 60x60 tile. The new standard says that any tile classified as BIa needs to have less than a 2mm bend. It does not matter if the tile is 30x30 or 1,2mx1,2m the maximum bend allowed is 2mm! This revision was the first to this document since its inception in 1998.

If the tiles do fall outside the standards, you obviously should replace them for the customer but as usual not after they have been installed. A professional tiler should be able to see an excessive variation by eye or by rocking the tile on a known flat surface any gap larger than 2mm at one end of the tile is clearly visible. Of course excessively warped tiles should never be installed on site. If they need to be removed and reinstalled, the tiler would be expected to do this at no charge. If there is any doubt about a tile, it should not be installed. As a supplier you should be happy to replace any tiles that are warped. According to ISO13006 a mimimum of 95% of the tiles should be free from any discrepancy that would impair the appearance of a large area of tiles. So If the number of warped tiles within the consignment exceeds 5% you have a valid reason to complain to your supplier.