Tiles have to conform to BS EN 14411. 82 pages but this is a snippet that will cover (at a guess) about 95% of all ceramics available today. There will be
standards for Natural stone too... I will need to try and find these
Extruded ceramics:
Tolerance from the average size = +2% to a maximum of +4mm
Tolerance for thicknes = 10%
Dust Pressed ceramics: (which most ceramics and porcelain are these days)
Tolerance from the average size (for tiles between 70 and 150mm) = +0.9mm
Tolerance from the average size (for tiles 150mm or greater) = +0.6% to a maximium of 2mm
Tolerance for thickness = +/- 5% to a maximimun of 0.5mm
(This also applies to rectified.... don't be fooled)
This shouldn't be confused with nominal sizing...... This is just a guide to the size contained in the box. The average size of the tiles contained must be within -10mm (based on the example given in BS EN14411 but I will need to dig deeper for the exact numbers).
Take Johnsons as an example. They make it clear on the box and show the nominal size as 200x100 (which is what most suppliers will advertise them as) but the actual working size may be 197x97 but credit to them, they also mark this on the packs. Most factories only provide the nominal size, so what you actually buy may be a very slightly different size, but still within the nominal sizing tolerance.
Its a bugger when we get a customer, orders some tiles to match some existing tiles which are 200x100, see a
tile advertised at 200x100, that then gets delivered 3mm smaller each way. One of the reasons that samples are advised and that tiles shouldn't just be ordered on a whim.
Another tolerance fact for you. Did you know that if you buy a
tile that has a slight manufacturing fault, like pits in the glazes or a printing error, as long as the fault only covers no more than 5% of the face, THAT IS ACCEPTABLE according to BS???? guess what else BS stands for!
Its way too early for this.... I need a coffee and 10 minutes brain rest....... "Tolerance"...... hate that word. Just another wall to hide behind.