Choosing correctly before installation is paramount.
Wall tile gap size.
I have looked at the fair trading publication which says that wall tiles should have up to 1 5 mm if i am interpreting it correctly.
The tile council of north america and accompanying tile organizations recommend an average grout joint width of 3 16 inch for every 1 16 inch variation in the size of the tiles.
For example while a difference of a 1 16 of an inch may seem small on a 12 tile this is readily apparent compared to a 1 8 grout joint.
Joint widths for wall tiles should not exceed 1 5 mm for pressed tiles and 6 mm for extruded tiles clause 5 4 6 c ii of as 3958 1.
Grout is a form of concrete and the gap between tiles can range from anywhere between one sixteenth of an inch to half an inch in size.
Once the tile mortar sets the installer can remove the spacers but cannot change the spacing.
When installing wall and floor tiles technicians place plastic spacers between each one to ensure the lines remain uniform.
Finished grout lines will vary from 1 16 to 3 16.
This creates a smooth final space that looks like solid tile.
Small tiles such as the 4 inch by 4 inch style commonly used on bathroom and kitchen walls often are self spacing.
Actual finished grout spaces will vary from 1 8 to 1 4 if 3 16 spacers are used.
Note that using the smallest grout possible will increase installation time.
A smaller joint will exacerbate the differences between tiles as the human eye can readily see very small differences as a percentage of the total grout joint.
Tile spacers range in size from 1 16 inch to 1 2 inch.
A higher quality tile could allow for a 1 16 or 1 8 grout line and maybe even a brick layout as lippage may not be an issue in a perfect tile world where as a lower quality tile might have major lippage risk so laying the tile in 1 3 s and having a 1 4 grout line is recommended.
For regular format tiles between 12 by 12 and 16 by 16 inches you can stay with those measurements or go up to 3 16 depending on the tile and the look you want.
If smaller spacers like 1 8 are used it will accentuate the size difference of handmade tile.