How Large Should Grout Lines Be?

by Roger

The size of grout lines for tile is something that comes up on almost every tile installation. The secret no professional will tell you is there is really no set or absolute proper size for your grout lines. There are some guidelines that need to be followed but the actual size is more of a personal choice than it is a set width.

Grout line guidelines

Since grout line widths are generally a personal preference I’ll let you know what mine are. I separate most tiles into three different categories:

  • Small format tile – Tiles up to and including 8 X 8 inches square.
  • Regular – 12 X 12 up to 16 X 16 inches square.
  • Large format tile – 18 X 18 inches and larger.

These are not technically official category names for tile sizes – it’s just what I call them. I’m weird like that.

Small format tile

A lot of smaller format tiles are self-spacing. That means that on either two or four sides of each tile there are what are called “lugs”. Lugged tile have small bumps or protrusions on the sides which are set directly against the tile next to it. Most of these tiles are made specifically for vertical applications, those are shower walls, backsplashes, etc., rather than floors.

The lugs on the tiles allow them to be stacked atop one another and keep the grout lines consistent throughout the installation. For tiles with lugs on only two sides of each tile you must make sure they are all stacked in the same direction, that the lugs are not butted against each other. Normally the lugs will create grout lines that are 1/32 to 1/16 of an inch.

For small format tiles that do not have lugs I will usually use 1/16″ spacers. Depending upon the texture and consistency of the tiles I may use 1/8″ spacers on occasion. For instance 8 inch slate tiles will usually look better with a slightly larger grout line.

If you prefer larger grout lines but have lugged tiles – don’t panic. You can still use spacers with the lugs. To ensure consistency you need to make sure that you either put the spacers between all the lugs or between the spaces the lugs are not. In other words do not put a spacer between the lugs on one tile and between spaces where there are not lugs on another. To figure out the size of your grout lines you also need to add the size of the lugs to the size of the spacer if you use the spacers between them.

Regular format

Regular format tiles are what I install on most of my jobs. More often than not I will use 1/16″ grout lines on vertical surfaces and 1/8″ lines on floors. I just think it looks better and as long as the tile is consistent enough, that’s what I’ll use. I will usually use the smallest grout line the tile will allow.

The best way to figure out how small you can go is to lay out nine tiles in a square and measure from corner to corner in both directions. If they are within 1/16 inch you can go that small with your grout lines. Some tiles such as slate and some quarry tiles will not be consistent enough to use a grout line that small. The largest grout line I will use is 3/16″ unless otherwise specified by the builder or customer.

Large format

Large format tiles are a bit tricky. These, more than either of the other two, are more dependent upon the tile itself. While most people will purchase larger format tiles specifically because they do not want a lot of grout lines, sometimes the tile will not allow it. Although this is rarely a problem, you need to be aware of it and make sure you check the tiles before you try to go with a very small grout line.

The easiest way to check larger format tiles is simply to measure corner to corner in each direction to ensure squareness. As long as they are the same in both directions, they’re square. Then measure several different tiles from different boxes. With a very good tile you should get exactly the same measurement every time. If that’s the case, you can use a 1/16″ grout line and not have any problems.

Large format tiles with 1/16″ or 1/32″ grout lines and a grout that matches the tile color closely looks great! If done correctly it will almost look like a single large slab of tile.

Which do you prefer?

As you can see there is really no absolute answer. If you like smaller grout lines, as long as the tile will allow it, use them. If you prefer larger, use larger. As a general rule do not go larger than 3/16″ although under certain circumstances such as some slates and quarry tiles, 1/4″ is acceptable.

If you choose to use smaller grout lines you must ensure the tile will allow it. If you don’t you may end up with lines that “jog”. That means the lines will not be perfectly straight and will jump over just a bit with every tile due to inconsistencies in tile sizes.

If you prefer larger grout lines you need to take into consideration the “grid effect”. If you do not use a grout that somewhat matches the tile color you may end up with an installation that looks more like a grid made of grout than tile with a grout accent. The smaller the tile, the more pronounced this effect may become.

No matter which you choose, you must make sure you use the correct type of grout. If your grout is chosen and installed correctly your good tile installation can turn into a great one. Make sure you consider your grout as much as you consider your tile. It can make or break your whole look.

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michael

I was kicked off of a tile installatphojob today. Why? The home owners wife originally wanted 1/4 in grout lines but the tiles are 13×13 so I dry set a section of the floor with 1/8 spacers and a section with 1/4 spacers. He chose 1/8 spacing. Who wouldn’t? He didn’t consult his wife about the change and apparently she flipped out after seeing a photo of nearly 300 sq ft of beautiful tile with 1/8 spacing. she tells him to tear it all out and start over. :censored: he tells me its my fault for making the suggestion to use a smaller line. I was so shocked I didn’t know weather to be mad at him or feel bad for him. Well after several hours I’ve decided it’s like this…she’s obviously got bigger balls than him cause there’s no way in hell I’d destroy that much set tile based on her Vision of a photo taken from a cell phone.can you believe some people? What a couple of bitches.. .excuse my language. :rockon:

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Chris

I am laying 12×24 porcelain tiles in a herringbone pattern. The tiles actually measure 11 13/16 x 23 13/16. I told the designer that the tile size makes it necessary to make the grout spacing at 3/16 as otherwise there would be a drift in the pattern of 3/16 per tile. She says I’m crazy, and I’m about ready to walk off the job. The math is simple, in a herringbone, or other complex patterns that use non-square (rectangular/ diamond cut out/ octagonal) the actual size of the tile plus the grout size needs to equal the tile advertised size, or am I completely wrong!

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Mark

Chris, I have to agree with your designer. As long as your tile setter is grouting on all four sides of the tile, there will be no drifting of the pattern. The first few tiles will set the pattern and continuity of all the remaining tiles. If the tile setter places the first few properly, you’ll be fine and no drifting will occur. That said, given your desired herringbone pattern and the size of the tile, I encourage that you use no more than a 2/16 inch grout line. You’ll like it. 3/16, in my opinion, is too wide for most interior finishes, unless you’re laying Mexican or some other rustic-looking tile.

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Roger

Hi Chris,

It does not need to reach what is called the nominal size. The only difference is that over a span of ten feet your grout lines will not be ten feet apart, they will be each tile size plus grout line times ten. Provided you use a consistent grout line (1/8″) in all the tile the pattern won’t drift at all.

For instance, if you grid out the floor with full 12″ tiles, you would grid perhaps a line every 5 5/8″ (with 1/8″ grout lines). The pattern will fit perfectly. If you have 11 5/8″ tile with 1/8″ grout lines you would simply grid out that line every 5 feet exactly, your pattern will still fit perfectly. As long as the tiles are consistent you will be able to set the pattern.

The ONLY time you run into the nominal size problem is when you have tiles of different sizes that should be manufactured to a specific pattern. For instance, a pinwheel pattern with 12 and 6 inch tiles. The 6 inch tiles would actually need to be less than 1/2 of one full tile. They need to be 1/2 of one full tile minus 1/2 of your grout line because you have two grout lines in every 1/2 tile for every full tile.

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Nayna

Hi Roger,

I just had bathroom wall tiles installed around the tub surround. I wanted the smallest grouting for the tiles, so I had my contractor use 1/16 grout spacers. The tiles have lugs, so once it was grouted, the lines look really large. Is there a fix for that?

Thank you

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Roger

Hi Nayna,

Unfortunately once the tile is installed you’re stuck with it. I know that’s not what you wanted to read.

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matt

Hi Roger,

I’m tiling a shower with 6.5×6.5 and 10×10 porcelain tile floor and walls. I prefer 1\8 grout lines.

The base of the tile is bigger than the surface of the tile. so if I use a 3mm spacer that goes deep (e.g. horse shoe shaped spacer, leveling system, etc) it creates a 3/16 grout line. If i use a 3mm spacer that doesn’t go deep (e.g. those soft crosses that i assume are not good for walls because they’re soft)it creates a 1/8 grout line.

What is typically the acceptable approach with a tile like this? I feel like the 3/16 grout line is getting to wide? Should i use a deep 2mm spacer (horse shoe or leveling system) in order to get a 1/8 grout line?

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Matt

Hi Roger,

I’ve been studying the tiles more closely and should add some info…

- The 6.5×6.5 tiles have 2 edges that bulge at the back half of the tile, and two edges that are smooth.

- The 10×10 tiles have a bulge at the back half of all four edges.

For the 6.5″ tile, seems like I need to position smooth edge vs. bulging edge for consistent grout lines throughout (adds about 1mm to grout line width when positioned this way)? Should I use a 2mm spacer to achieve a 3mm (1/8) grout line?

The bulges on the 10″ produce an extra 1.5 – 2mm grout line width. Should i be using a 1.5 – 2mm spacer to achieve a 3mm (1/8) grout line?

Just curious…why are the tiles manufactured this way.

Thanks in advance. –Matt

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Roger

They are manufactured that way to get them out of the form. If they were rectified they couldn’t pop them out easily. That’s why rectified tiles are cut after they are formed and baked (one reason).

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Roger

Hi Matt,

I use the soft spacers on floors specifically for that reason. It remains a 1/8″ grout line.

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Tiffany

Hi Roger. I’m redoing my bathroom and putting 12×12 tiles on the floor and walls. The wall is a mosaic tile and the floor will be a slate tile. What size grout lines do you recommend?

Thanks,
Tiffany

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Roger

Hi Tiffany,

With slate you usually want about 3/16″, they can be highly inconsistent (the tiles). I prefer about 1/16″ for walls and any type of mosaic.

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Steve

Q. How thick should the grout lines be?

A. As thick as the gap between the tiles. :bonk:

(Maybe you meant; How thick should the gaps between the tiles be?)

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Roger

Hi Steve,

The gap between the tiles is the grout line.

Q. How wide is your tile

A. The same as the distance from edge to edge. :bonk:
:D

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Lindsey

Hi Roger,
I plan on tiling my kitchen. I removed the wall paper and under it is what seems to be a sheet of thin faux looking tile something from the sixties… kind of wall covering… it is it seems to be stuck on very well in most places we gouged it a couple places and the top layer kind of chips off in some areas… … I’m wondering if tiling over this will be ok or is removal necessary?
Thanks so much! wonderful site.

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Roger

Hi Lindsey,

Unless I know exactly what it is I recommend removing it. Even when I know what it is I recommend removing it. :D

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Effie

Hi,
My tiler just told me I need to pay $25 extra per m2 for a 1mm grout line for my 60x60cm porcelain tiles in the bathroom. He is already being paid $60 per metre and wants extra as he says there is a lot more work in smaller grout line as he uses special grips to hold tiles close together. Is he trying to rip me off? He also said that tiles could be uneven or chip if too close together. Any advice?
Effie

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Roger

Hi Effie,

A tighter grout line requires a lot more work, and perhaps a leveling system. It is common for an upcharge under these conditions. How much of an upcharge is relative. There is no ‘normal’ amount, so I can’t tell you whether that’s more than normal or not.

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Maureen

Hello Roger,

According to the James Hardie installation guide at http://www.jameshardie.com/homeowner/pdf/backer-install-us.pdf

on existing floors:

• HardieBacker® cement board may be installed under or over Vinyl Composition Tile (VCT) and other resilient flooring. For best results, remove existing floor covering, especially if it is in poor condition.

• If installing HardieBacker cement board over existing floor, ensure the floor is flat and floor covering is thoroughly adhered to the subflooor.

My bathroom floor has peel and stick vinyl tiles. They are in very good condition, and the floor is flat and level. Is there any real reason to remove the tile before installing the hardibacker on top of the vinyl? If so, why do the installation instructions say it can be put over the top?

Love your site … thanks!

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Roger

Hi Maureen,

If your existing floor is over wood and you can install thinset under the backer and screw it down then there is nothing wrong with that at all. If you are relying on thinset to bond your backer to the floor then you are 1) using it incorrectly and 2) it won’t last. The hardi needs to be mechanically fastened with screws to the subfloor.

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Maureen

Thank you so much for the quick response! This will save a lot of work, as I believe if I remove the tile, the glue that is under it will not be good, then I’d have to remove/replace underlayment also. I plan on following the instructions you’ve given for installing the hardi … thinset, correct screws, tape. One other question I have is the thinset. When I looked at it in the big box store, the label doesn’t specify whether it’s modified or unmodified, and some of them say for walls, and some say for floors. How can I tell which thinset to buy?

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Roger

The bag will always state whether or not it’s modified. It may say ‘polymer fortified’ or polymer modified’ or something similar, but it will always say. Most thinsets you get at a big box store will be modified, it’s actually difficult to find a non-modified. You can read through this to see what an unmodified it, but they’re scarce at big box stores: Unmodified thinsets.

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Maureen

Oh, I was looking at the pre-mixed tubs. I hate mixing stuff myself. The results are always too thin and wet, or too dry. That’s why I don’t cook, either! Can I use a pre-mixed thinset?

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Roger

No, you need to use the powdered stuff. If you follow the mixing directions on the bag it’ll come out perfectly. :D Pre-mixed ‘thinset’ is not thinset, it’s mastic with sand in it.

If you have any more questions can you please post it as a reply to this one? I have (literally) over 20,000 questions on this site. If your question is not posted as a reply then I have no idea what you’re talking about and need to go search for your previous question and my answer to it. Thanks.

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Nicole

Hi Roger,

We had 18×18 porcelain tiles installed during our home renovation project. We made it perfectly clear that we wanted the thinnest grout lines possible, even to the tile setter as he was working. The end result is a 1/4 inch grout line, with a light colored grout that is already staining. The company we hired says that the 1/4 inch grout line is perfectly normal, and that anything thinner would be impossible. Also, instead of re-grouting the light color (which they helped me choose), they are pushing a grout stain. Given your experience, could you tell me what the best course of action for fixing this floor? Would a grout stain be any good? I read that it is very similar to paint. I feel at the very least this floor should be re-grouted.

Thank you! Any advice would be greatly appreciated. :)

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Roger

Hi Nicole,

Your particular tile dictates acceptable grout line size to an extent, but 1/4″ is HUGE! It’s absolutely ridiculous, to be honest. Grout stain does work very well, but it’s up to you if you want them to regrout. I don’t know how good it would look on 1/4″ grout lines, though.

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Nicole

Thank you, Roger.

I know it is ridiculous. They are adamant that 1/4 inch is industry standard, so it looks like I am stuck with it unless I want a lien on my house. Unfortunately, every tile job that was done on the house was done poorly, so I have already had to fight to have a floor and shower tile ripped out. Your response does make me feel like I maybe should be fighting this one as well. I appreciate your help. :)

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Stephanie

Hi Roger,
My contractor just installed 3×6 carrara marble subway for the kitchen backsplash with no spacers, so each tile is butt up against each other. I assumed subway should have a 1/16 or 1/8 grout joint so I did not specify and came home to see it like that. Some areas look ok, but others have obvious lippage. After expressing concern he attempted to remove some of the pieces that looked really bad, but since the tile was installed so close to each other it caused the tile around the removed tile to chip and so on. Now I end up with chipped tiles and less lippage. He said removing more would make it worse.

It was now grouted over and it looks worse than ever making the lippage areas look “3d” and the chips are of course filled with grout. I’m sure he will re-do if I ask. The question is, will it cause more problems ripping everything off and possibly needing new drywall and doing all the prep? I worry that it might affect our newly installed quartz countertop since it was grouted from ceiling to countertop. OR…should i just ask him to remove the eyesore chipped pieces to the best of his ability and call it a day. We could have hired a tile expert to install this, but due to budget our contractor offered to do the install, but if I knew it would look like this I would have paid extra to have it done right the first time. Thanks for any suggestions!

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Roger

Hi Stephanie,

It’s completely up to you. Ask yourself this question: Would you pay someone to install a backsplash that looks like that? My guess would be no. In that case have him remove it, repair the wall (it will get torn to pieces) and install it correctly. The ‘fix’ is simply a band-aid, akin to use after cutting off your arm. It’s ‘something’, but it’s not the right something.

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Stephanie

Thanks Roger. Contractor’s solution as an alternative to gutting is to sand the polished marble making it a honed finish to get rid of chips and lessen the look of lippage. I like honed and polished equally, but my concern is if this even a good option? Can this be done even with grout installed? Thanks!

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Roger

Yes, it can be done. But it needs to be done by someone who knows how to do it. It requires more than simply ‘sanding’ it.

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Matthew

Hi Roger,

Quick question my wife and I picked 12 x 12 tiles and decided we liked the larger grout lines so we went with 3/16″. The tile was placed at the front door and back door so we were not coming in and stepping on our wood floor. So we placed transition strips in between the tile and wood floor. We happen to like the grout lines larger, do you think the grout lines are to large for a smaller area (15sqft at front and 15 sqft at back) just in front of the doors? We like it and have had several people say they like it and some not so much. Any suggestions you have would be great before I mortar the tiles in place.

Thanks

Matthew

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Roger

Hi Matthew,

Grout lines are a subjective matter. It really makes no discernible structural difference between 1/8″ or 3/16″ grout lines. If you like the larger ones there’s no reason you can’t do that.

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Tiffany

Hi Roger, your website has been super helpful! One quick question – for a tiled kitchen backsplash, is greenboard an acceptable substrate for that? We currently have greenboard up, and we’d prefer to not put another layer up for the tile to go on if possible. Thanks so much!

Reply

Roger

Hi Tiffany,

Yes, you’re fine with that.

Get to tiling! Whaddya waitin’ for? :D

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Bill

Hi Roger. I just found your web site and love it. I’m going to be putting 12×12 inch ceramic tiles on my shower walls (from tub to ceiling). The walls are green sheetrock. I’m just checking if using an adhesive is better than mortar here. Thanks.

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Roger

Hi Bill,

Doesn’t matter what you put it up with if you’re installing it over green sheetrock, it’s gonna fail anyway. Green sheetrock (greenboard) IS NOT a proper, nor approved, substrate for tile in a wet area. It disintegrates when it gets wet. And it will get wet. It’s that simple. You need an approved substrate up there like densshield, cement backerboard, or you can use kerdi over the greenboard. But you need something behind your tile to waterproof your substrate and prevent water from making your wall disintegrate. If you download my shower waterproofing manual it will go a long way to explain what you need.

Reply

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