QUESTION

I purchased 8" pressed ceramic tiles and I have a question about the facial dimension tolerances. The tiles I received were manufactured in two different facilities and upon install I found out that the tiles are different sizes. When 10 tiles are measured out the difference is about 1/2" which has really messed up my grout lines. I have reached out to the manufacturer requesting a spec sheet, but none has been produced yet. It is my understanding that these tiles are ANSI certified but in my limited knowledge and research they seem to be out of the acceptable tolerances. I am just looking for suggestions on where to go from here. Thanks!

ANSWER

ANSWER - The manufacturing standards for ceramic tile (porcelain is a type of ceramic tile) in the USA are stated in ANSI A137.1 and ANSI A137.3 for Gauged Porcelain Tile Panels/Slabs.  Large Format Tiles are covered under ANSI A137.1 as well as mosaic tiles.

All ceramic tiles will have some variation in their facial dimensions, in degree of warpage, color variation and for other physical properties.  When tile is produced it comes out of the kiln with variations.  So the manufacturer will separate the tiles into caliber groups so the the tile within the group meet the required tolerance standards.  So it is possible that if you mix different shipments or caliber of tiles that the range within the mixed group will not meet the industry standard tolerances.

Calibrated tiles are tiles that come out of the kiln and are sorted into groups where they meet the tolerance for Nominal Calibrated tiles.  Rectified Tiles are tiles that after they come out of the kiln their edges are ground down to be more consistent within the group the standards for those tolerances are very tight.

When tiles are produced by different manufacturers, there is no standardization that requires them to meet some particular nominal size so they are compatible with other tiles.  There are many different types of tiles and they can be manufactured in different ways with different types of equipment.  Some manufacturers produce their tile to be installed with a certain width grout joint because they might have more variation in sizing with their tile.  So even though they can produce any nominal size, they do have to label their packaging on how many square feet the carton will cover based on the reported grout joint width.