Just finished a bathroom using Porcelanosa Queens interlocking tiles. Grout line is less than 1mm

After speaking to Porcelanosa uk, found out that these tiles had passed all certification needed to be used with high flow showers.
The tiles were supplied with grout 0-4mm.
Just intrested to here your thoughts about using tiles in shower areas with grout lines less than 1mm

After speaking to Porcelanosa uk, found out that these tiles had passed all certification needed to be used with high flow showers.
The tiles were supplied with grout 0-4mm.
Just intrested to here your thoughts about using tiles in shower areas with grout lines less than 1mm