Tile spacing both above and below 1/8", what type of grout should I use?

Question

I've laid tile sheets for my back splash in my kitchen. The tiles on the sheets are not exactly the same by length (in comparison to the corresponding tile on another sheet).

Therefore I have grout lines which are mostly between 1/16" and 3/16" (but not consistently one or the other). There are also some where the tiles are almost touching. Most of the spacing between tiles on each sheet are 1/8" (though they vary as well, mostly larger)

I've read that unsanded grout will sag in a space larger than 1/8".

Which type of grout should I use (sanded/unsanded)?

Also one more thing, the store I bought my tile from sold me a bottle of Flexible Grout Admixture. Should I use this in place of water or is it just a sales gimmick and I should return it?

Thanks!

Answer 1

I would use sanded grout.

You will have to work harder to force the grout into the narrower gaps, but it will fill. It will self strain the sand particles out. Try wiping left-right and diagonally with the grout float pressed very firmly to the tile

The admix is a good thing. It makes for better troweling properties, which means it will level better.

Answer 2

There was a time when there were no grouting materials and people were using ceramic tiles. Back in those days people have used cement based mortar as a grouting material. Even today for exterior application people use it, because many of them claim that it is still the best grouting material. Also, ceramic tiles weren't always this perfect in shapes and sizes, that’s why distance between tiles had to be bigger than today, sometimes as big as in your case. I have never seen cracks in this type of grouting not even when it is really old, so that’s what I suggest. Now with tighter gaps you will have some difficulties in pushing it in but I think you can do it.