If your tiles are sawn stone (nature stone)such as granite, etc, then narrow grout lines are fine. If they are clay or ceramic they will have edge variations from being fired in a kiln. Wide grout lines will allow for straighter lines while hiding these variations.

I'm sure a tile expert will be along and can explain it in greater depth than I can.

consider this a bump

You get thin grout lines by putting the tiles really close together (use 1/16" spacers). Some tiles have built-in self-spacers. And the bevel on the tile can impact how big the grout lines are because even if the tiles are 1/16 apart, the bevel on the tile limits how far down into the crack the grout float can go to scrape out the excess grout. That's why stone tiles with square edges can have smaller effective grout lines.

Sorry, but you can't do that with all tiles. Spacers aren't that good. Debbie was closer with her explanation, however, there IS a kind of ceramic that's baked in sheets and then cut to size afterward, making it just as good a candidate for tight joints as granite and marble, and that's rectified porcelain. The only other tiles you can set with a tight joint are SOME wall tiles, and they'll have spacing lugs on the sides. But for the most part, you're better off with a 3/16" grout joint

Bill, what are the problems one can have with a closer spacing of say porcelain floor tiles?

Does backsplash glass tiles need to be 3/16" as well?

Your surface prep has to be more perfect if you want thin grout lines. Wide grout lines allow unevenness to be hidden more easily.

As well as sizing of the tile.

My contractor uses the stir sticks from Starbucks. He said they give him the best results.
Donna

There's something even better than the stir sticks, and it can be used over and over again. It's called a CHALKLINE!! :-)

Bill: What is it that you can't do with all tiles? 1/16" spacers?

Correct. What I'm about to show you is an extreme example (and yes, it got torn out and redone before the GC could even object), but this is the kind of out of square problem and sizing problem that causes a need for a decent sized joint. Usually it's not this obvious, but none the less it does exist in just about every single tile installation. This is also the reason I don't like the use of spacers instead of gridding out the floor with chalk lines. In this first pic:

If you notice, all the way down, one side of the tiles all line up. If I was using spacers, that never would've happened, and I would've been blamed for the floor being so out of whack, and I would've had to eat that floor. With chalk lines, it's very easy to see if it's workmanship or not. Here's a closer pic:

What about rectified tiles? I am using a porcelan rectified tile (17 x 17) in my new master bath laid on diagonal. I thought you didn't need any grout lines (or at least very little) with this type of tile. Am I correct?

Yes, you're correct. The difference in rectified tiles and conventional is that rectified tiles are cut to size AFTER coming out of the kiln, so their tolerances are much much tighter, and you can set them with a 1/16" grout joint.

On the chalk line method, some basic questions:
1. Do you line up the tiles so that the centers of the tiles align to the chalk line (thus having smaller "ragged" edges on both sides)?
2. How do you keep the line in sight when you trowel the thinset over top of it?
3. How do you line them up when it's not a straight pattern, like a hopscotch?

I've been using spacers, but have dealt with the off-spacing by just adjusting the tiles by eyeballing when I get too much space, to even it out on either side. I originally thought I was the world's worst tiler when I was getting variable spacing, until I learned that the tiles come with that variation. :-( I like the idea of having a more precise method to get them lined up and spaced correctly.

1) The tiles are aligned as shown in the following diagram:

2) When I come across the first "row" with the thinset, I'll generally not spread the thinset across every other, or every couple of lines, using the corners where they hit the lateral line at the bottom of the row I'm spreading. After that, though, it gets much simpler, using the tiles that are already set and the intersectig corners at the bottom to keep everything straight, and then every few rows, I'll get up and stand back and eyeball the installation to that point to make sure there aren't any "dingers" that I couldn't see close up.

3) How much time do you have? LOL This is over simplified, but it basically comes down to snapping a few control lines and doing alot of measuring off of them.

This may be a dumb question. But, would a thinner grout line be harder to keep clean over time?

I'm trying to post a photo and I won't know if it worked until I hit post. So if this is a blank, I'll keep trying. But, if it did work, this is 17 !/2 x 17 1/2 rectified porcelain being installed floors and walls, 1/16". Also, at the top is Shluter edging.
/Users/bonitagoldman/Desktop/Picture 1.png

Oh heck....it didn't work. Grrrrr Sorry

Third time is a charm! I hope.

Here is a link that might be useful: bathroom wall

Thanks for the picture. I'm thinking of using Schluter edging w/glass mosaic border. Are you happy with the Schluter edge? I love the look of the thin grout lines but do you think it would be hard to get to cleaning wise over time?

I love the Schluter edge and am extremely happy that there was no matching bullnose for my tile. It's clean and neat.

I have very thin grout lines in my kitchen and have no problems keeping it clean. It's never been an issue.

This may be a dumb question. But, would a thinner grout line be harder to keep clean over time?

Not at all. Matter of fact, the thinner the grout joints the easier they'll be to keep clean.

Thinner lines are eaiser to keep clean: grout is a little porous, and can be a tad rough if the installer wasn't on his game.

So the thinner the lines the less there is to clean.

And if you are really concerned with keeping it look nice, go with as dark a color as you can possibly stand. I have a charcoal color in my coat room and laundry, and it never needs a bit of attention.

Thanks for the lesson, Bill.

I used chrome Schluter edge to finish tile instead of bullnose. My contractor did a miter cut (45 degree angle)on corner wall. The edges are protruding with sharp edges. My daughter has already cut herself once, it's the wall next to the sink vanity. What can I do to smooth out the sharp edges when it's already installed? (Contractor from hell is gone)

There's not much you can do, other than maybe filing it down, which might open up a small hole, but that would be better than someone cutting themselves again. This is what he SHOULD'VE done:

Schluter makes small little outcorner inserts, both 90 and 45 degree, that you can use, so that you don't HAVE to miter the ends.

We used pennies as spacers.