Width of tile floor grout - breathe?

[sepani]

Hello,

currently laying tiles on the lower floor (basement). The tiles are 60x60 and underneath there is water-borne underfloor heating from LK. I'm wondering about the grout. Does its width have any significance for ventilation? I got a tip from someone that it should be as wide as possible, but I would prefer it to be as narrow as possible... preferably not over 4mm. Does anyone have a good tip?

Buggaren

 

[SBH]

you can make it as wide or narrow as you want. but under two millimeters doesn't work well.