Q. What is the Australian Standard, and how do I know if the variance in my tile is normal and standard?
A. The standard permits a variance in length and width from the nominated work size of +/- 0.6%, with the maximum not to exceed +/- 2mm. I.e. A 600x600mm tile can vary in size between 598mm to 602mm (a variance of 4mm)
Q. What is the nominated work size?
A. Tiles are broken up into three categories as below:
• Nominal Size – This size generally describes and groups the product approximate size, e.g. 300mmx300mm / 600mmx600mm). Nominal Size is the also the size labelled on each box.
• Work Size – The size the manufacturer is endeavouring to make. Work Size is the actual size of the tile and should not be confused with the nominal size used to describe the product.
Please Note: Tiles may have different work sizes (calibre) despite being the same nominal size.
When combining tiles of different work sizes, wider grout joints may be required to allow for size variation and tolerances within the tile.
• Actual Size – The finished product size (actual tile size) and the tile size obtained by measuring the face of the tile in accordance with the Standard.
Q. How do I know if my tiles comply?
A. If you measure ten tiles in both length and width (40 measurements) to obtain the “average actual working size,” then the Australian Standards (Tolerances) above apply.
So, if the average Work size of the tile is 297x599mm, then the tile can be 295 – 299x597 – 601mm.
Tiles that meet these criteria are deemed acceptable and of First Quality.
The Standard recommended grout joint of 3mm per AS 3958.2023 Guide to Installation of Ceramic Tiles generally provides sufficient tolerance to accommodate tile size variation and allow for adequate tile placement.
Adding to the above, using a 2mm grout joint or smaller is the customers, clientele choice, but it may not be achievable if the substrate is not entirely flat, plumb, or true.