According to TCNA guidelines, the minimum grout spacing is 1/16" Depending how flat the tiles are, how flat the wall is, and how skilled the contractor is all factor into the grout joint width. If the tiles aren't perfectly flat or rectified, chances are a 1/16" joint could be the smallest you can get. If that.

Cutting glass tiles can be a challenge. Have your contractor cut a few and show you the outcome before installing the first tile. Some cut easier at the ends than in the centers. No way to know until you try a few.

Be sure to use a dry powdered white thinset you mix with water which is specially made for use with glass tiles. Laticrete GTA and CBP's GTM are both good products, although I lean towards the Laticrete every time.

Also be sure to flatten the trowel ridges after spreading the thinset. This will eliminate the thinset marks seen through the tiles and the bumps showing in the grout lines.

You also want to avoid any L shaped glass tiles as the glass tiles can crack starting at the inside of the L, sometimes months later. These corners should be as rounded as possible.

Part of the reason for gaps / spacers / grout joints is to provide for expansion and contraction of your house and the building materials used in it.

Yes, EVEN YOURS will expand and contract ! I don't care what new and expensive uber nano tech product , glue, thinset, tile , ect... is used or how experienced your tradesman is. The laws of physics still apply.

Don't even bother with the test run - YOU MUST USE SPACERS with glass tile.

PERIOD !

C&R's advice is also pertinent. Glass does not like to be compressed.

Thanks, everyone! Your feedback is really appreciated. Two more questions: Is there a specific technique or template to cut the tiles rounded around the outlets, or will the installer know how to do that? Also, if I asked the installer to do just one 2 ft section of backsplash , just to make sure he's doing things right, how long would we need to wait before things are obvious (as to whether it looks good or bad?). This may cost me more, but I don't want to take a chance with him messing up the job.

Any particular reason why one would use Laticrete over Custom Bldg Products? The 3x12 tile that I'm using has a white backing, but no mesh. And finally, any particular 1/16" spacers to use? My understanding is there are 'leave-in' spacers, and spacers that you remove.

Your installer should know what he's doing before the first tile goes in. You can look over his shoulder but..... If he lays the first tile on the counter with no spacer between the counter and the tile, send him packing. Even with the painted backs we still flatten the trowel ridges. Use either the Laticrete or the CBP, whichever is available locally. Ceement doesn't ship easily. I'd defer to a softer spacer which is removed after tiling. Any leave in spacer will be seen through the edges of the glass tiles.

How do you do rounded corners?

Usually use our wet diamond saw blade