hi guys i've recently just tiled a bathroom floor.I have screwed all floorboards down so there is no movement then i 18 mm ply'd the floor screwing at 200 centres so the floor was totally solid no movement whatsoever.I layed 330mm x 330mm ceramic tiles onto the ply with a norcross rapid set flexi adhesive and have grouted with a charcoal grout (flexible)by stoneset.On looking at the grout very closely i can see hairline cracks on some of the grout lines(not all).How can this of happened or is it nothing to worry about? Could it of been that on the packet it says leave for 24 hours and maybe they have walked on it too soon?you cant notice them unless you actually get on the knees and look very closely but just thought id double check if its ok or it needs bringing up,not that i want to that is.All advice appreciated thanks.

Ive had the same problem twice with Granfix recently

I've had the same problem with Granfix flexi floor grout recently too. I did an ensuite and a bathroom which were back to back in the same house. The ensuite floor grout developed hair line cracks, so I assumed I had put it down too early before the adhesive had fully set. So I scraped it out a week later and re-grouted, but it still developed a hair line crack, although not all over the floor this time. The bathroom hasn't cracked at all. The ensuite is an inner room with no windows and a lot warmer that the bathroom, so I wonder if the grout is simply drying out too fast...

hard to tell if this is just a granfix problem or if something else has been at work. It does sound a bit iffy for granfix tho'

Mapei reccomend that the joints are dampened before grouting on ceramic, don't know what other companys say but if there's high suction in the joints the moisture will be dragged out and will not allow the mixture/grout to cure properly. It's the same with sand/cement on walls, you must stop any excessive suction or cracking can accure

so what would the solution be for this? just leave it as it cannot be seen or......? just dont want it to be a problem in 6 to 12 months

Invite the customer to see the job and ask if their happy with it, if they say yes, leave it but make sure you stipulate that if they get any problems later don't hesitate to call you.

thanks for the reply's guys