What are tile tolerances?
Tiles are made by pressing various materials into a mould under high pressure before being fired in the kiln. The finished product is a tile in the shape of the mould and is generally sold in this way with a ‘non-rectified’ edge. These tiles are then sorted on the packing lines into different batches for colour and sizes or calibres.
In some instances, the tiles go through a ‘Tile Rectification’ process in which they are cut to one specific size, which avoids having different sizes or calibres. To avoid having different sizes and calibres, some tiles are produced and are then cut down to one specific size. This is better known as ‘tile rectification’
What are tile tolerances?
During the kilning process and extreme heat, the clay and other materials can expand and contract, causing slight variances in the dimensions of tile from the original mould, these dimensions are known as a tiles’ working size and can vary from batch to batch.
Because of the manufactured nature of the product, a level of tolerance is formed when it comes to the actual tile sizing of both ceramic and porcelain tiles.
How are tile tolerances calculated?
Tile tolerances are calculated using the ‘working size’ of the tile and not the ‘nominal size’. The nominal size (what is generally displayed in the product description) is the size of the tile mould, whilst the working size is the size of the tile specified for production to which the actual size conforms within permissible tolerances. For example, a 30 x 60cm tile will have a nominal size of 30 x 60cm but it’s working size (or calibre) could differ and be 29.5 x 60.5cm.
What is the tile tolerance for a non-rectified tile?
The maximum tile tolerance on a ‘non-rectified’ tile is +/- 2mm, however it is unusual for tiles to vary by this much, but these are the tolerances that are deemed acceptable. As a result, a grout line of between 3 – 5mm is recommended to accommodate any size variance, particularly on tiles larger than 40mm.
Tile tolerances of non-rectified tiles are based on the size of the tile:
- Tiles less than 7cm have a maximum tolerance of 0.75mm
- Tiles measuring between 7 – 15cm have a maximum tolerance of 0.95mm
- Tiles larger than 15cm have a maximum tolerance of 2mm
What is the tile tolerance of a rectified tile?
Whilst the same tolerances of +/- 2mm apply to rectified tiles, they have tighter sizing controls due to the tile rectification process and are less likely to have such variances than ‘non-rectified’ tiles. Therefore, rectified tiles can be installed with smaller 2 – 4mm grout joints (with a minimum of 3mm for floors).
Need more information?
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