minimum tile spacing in a shower area

never have myself. customers come in all shapes and sizes dont they

 

The only prob I can see is if that tiny gap makes it difficult to get the grout right in to the gap to make a watertight seal. With a larger gap you could use a rubber float (is that what you call them) to grout over a large area of tiles, and the grout will fill the space easily. But with a 1mm gap, I can see you having to use some sort of soft, but thin, blade to force the grout right in with its edge.

Any trapped air bubbles or gaps will surely lead to the inevitable. Is the backing board fully waterproof? Cement-based adhesive and grout being used?

 

just use a slightly wetter mix of grout,and grout as normal

 

Is the customer actually aware of how big(or small) 1mm is?

I know some can't envisage measurements/sizes very well!

Mr. HandyAndy - Really