The tile manufacturer has stated grout and spacing specs for their product; what are they recommending? Follow those.

Thank you, Skippack. The tile isn't in yet but I want to purchase the grout before install on Wednesday. The tile company website just has a link to the TCNA handbook for install guidelines.

Thank you, Patricia. I am worried about my installer. He's my GC and has done tile work for us in the past, but when I mentioned I wanted the smallest grout lines possible and asked him which kind of grout, he replied with Sanded. I have read that unsanded is best for small grout lines.

You should have done back painted glass. 3/16 is the usual minimum to account for standard movement. Any thinner and you get cracks in glass when temperatures change and movement happens. A backsplash experiences an extreme change in temperature during cooking and then cooling. You don’t want glass shards in your food.

You need a different installer. And maybe a different material.

Glass tile installations generally require a skilled tile professional as experience with glass and possessing the right tools are important. These questions would generally be answered by your experienced pro after they inspect that particular tile and review the manufacturer's instructions (which should be included in the packaging). Your selection is a larger format and 1/8" grout joint would generally be recommended. As for the type of grout, once again refer to the manufacturer instructions but an experienced tile pro will have the knowledge and experience to make this call. I might add that most pros will provide the grout. We have our preferences for a reason. I often use Permacolor (which technically is sanded but it is a very fine silica sand so unlike other traditional sanded grouts), or Permacolor Select which in unsanded, but again, glass tiles are not all the same. You should also consult the manufacturer regarding thermal expansion and minimum distance from a heat source. Your concern about the installer's qualifications may be merited.

Thank you, Dragonfly. I am having serious concerns about him doing the tile work. He's a fantastic guy/GC and has done amazing work, but I'm thinking I need a tile professional for this. Thank you for all the information!

Outlets in backsplash might be challenging with that large a glass tile- they tend to shatter or crack. Or they look great until the electrician comes back and tightens the screws in the outlets.

I know this isn’t helpful I’m sorry.

Remember that your backsplash can easily wait until you find the right pro. Removing things from your countertops for a few days is not a terrible inconvenience. Have a client that has been deliberating over her backsplash selection for over a year. Found us and after consultation finally narrowed it down. We ordered the tile which is sitting in our shop and they have patiently waited for us to get a space in our schedule to install which will finally happen in the next few weeks. They actually like the fact that they will have this "new" element to enjoy some time after the rest of the project was complete.

I do agree backpainted glass would have been a good choice and IMO a GC is not a tiler and obviously has not worked with glass tile sanded grout will scratch them horribly.