Porcelain Tiles and Tolerance

The manufacture of porcelain tiles starts out with a combination of various materials in granular form that is pressed into a mould under high pressure then fired in kilns. The finished product is a tile in the shape of the mould which, as like a batch of baked cakes, may not be perfectly the same. Porcelain tiles sold straight from the mould have a slightly angled edge – known as a ‘natural’ or ‘moulded’ edge. The tolerance to European standards on this finish of tiles is up to 3mm. They don’t normally vary this much but these are the tolerances that are deemed acceptable. It follows that a joint width of 3-5mm is recommended for natural edged porcelain tiles.

Porcelain tiles can also come with a ‘rectified’ edge. This is where the tiles taken from the mould are processed through machines that trim the edges of the tiles leaving a sharp, square rectified edge. The tolerance on the machines cutting these edges is very small indeed, making each tile practically the exact same size as the next one. As with ‘natural’ edge tiles, there is always a tolerance but a minimal 0.5mm. This rectifying process enables installation with a minimal 2mm grout line, giving a sharp finish to the project.

As a manufactured product you can expect porcelain tiles to always be the same thickness however, overall dimensions may differ from published sizes and from batch to batch as detailed above. Also, in the construction and engineering industries, the term nominal size has been adopted to describe a manufactured product approximate size. For example, in the tiling trade, you’ll read or hear sizes of 600×600 to describe a medium-sized square tile, when in fact the size could be 595mm x 595mm due to variation in manufacturers machinery, processes, and materials used.