Looking for proper method for grouting wall joints for custom tiled shower. Shower is floor to ceiling. Porcelin 6x6 tiles used with 3/16" grout space. Construction includes one exterior wall and one interior wall of 2x4 construction. Vapour barrier, covered in "durarock" cement board. All cement board seams were finished with mesh tape and modified thinset. I have read that "cold joints" were walls, floors and ceilings meet will crack if grout is applied in the same fashion used on wall tiles. I have heard of several methods: just grout, using silicone, install polytube and cover with grout. Is there a proper method for these joints

Silicone only is the best method to caulk corner and verticle/horizontal transitions.

This sounds like the easiest method. I was always under the belief that silicone as water proof and mildew resistant it might be always becomes a source for mildew?

There's nothing in silicone that mold can feed on.

Do I grout the entire shower, leaving all the verticle and horizontal transitions grout free. When grout set go back and silicone? What is the best way to grout everything and keep the transitions empty?

After 24 hours you can caulk the joints. Make sure grout is dry before caulking.

Once you have done the final wipe, take a small pick and scrape out any excess grout before it hardens.

I have basically the same question, with a twist. I am using a silver grout but I cannot find a grey/sivler caulk anywhere. What do you suggest, clear? If so the seam be more noticable with line down the middle. When you sasy small toothpick you just mean take out just enough so the the 2 walls do not touch?

Thanks,
Stephen

Go to groutgetter.com. They have every most brands and colors, sanded or unsanded. If you don't see the color you need, send them an email and ask. They can probably make it for you.