Silicone over Flexible Grout in Internal Corners?

[hammerandnails]

Hi all,

As per the title, my tiler has grouted the internal corners of our new shower enclosure with a flexible tile grout. I found this out when visiting him at the end of the job, when he said it just needs siliconing on top, asking if I was happy to do it myself. At the time I thought nothing of it, but did some research before siliconing the internal corners myself and it seems this isn't best practice.

1. Is it OK to silicone over the top of flexible tile grout?

2. If not, what building standard / rule can I quote so I have a leg to stand on when I ask him to correct his work?

If it makes a difference, the arrangement is: stud walls, mapex tile backer board (12.5mm thick), adhesive, marble tiles (10mm).

Thanks

 

[Slippery]

He shouldn't have grouted the corner, it's better to have a small gap for the silicone to get a good key. I would rout the grout with a stanley knife and try to get as much off as possible, make sure you use a sanitary silicone!