A common misconception about tile and grout is that grout will somehow assist in stabilizing a tile installation. It does not. Unless you use epoxy grout it will add no significant structural elements at all.

So why should I use grout?

Grout is, structurally speaking typing, simply there to fill the spaces between tiles. That is an oversimplification, but it describes the grout’s function. More to the point, it is there to keep other things out of that space. Without grout the possibility of dirt, grime and all sorts of unruly, unwanted things may collect in the spaces between tiles. This may lead to not only unhealthy conditions, but also the chance of damaging your tile while trying to remove those things.

Does epoxy grout help stabilize tile?

If you’ve read any of my other posts regarding grout you have more than likely seen me state that epoxy is different. This subject is no exception.

Epoxy grout will actually add to the stability of your tile installation – to an extent. Epoxy will stabilize only the area between the tiles – the grout lines. It does not stabilize your tile enough to replace proper installation methods. This is not what epoxy grout is intended for.

A couple of reasons for using epoxy grout include the durability, ease of cleaning, and its ability to withstand staining. It is not intended as a product to make a sub-par installation correct.

How does epoxy help?

To the extent that it does stabilize your tile, it will only do so in the direction of the plane. If you think about tile on a floor epoxy grout will not (to any significant amount) stabilize your tile up and down. If you have a corner of your tile that does not have support beneath it, the tile will still crack eventually. It will take a bit longer because of the epoxy, but it will still crack.

If you have two tiles (not installed on anything) that are held together by epoxy grout between them you can grab each end and bust them over your knee like you would bust a baseball bat  (if you were insane) and they would break apart. You can not pull them away from each other and pull them apart – ever. That is the direction of the plane.

So although epoxy grout does add some stabilizing features to your tile installation it should not be used in that capacity.

Grout is an integral part of a correct tile installation but not in a structural way. As you plan your installation keep that in mind and treat your grout simply as an aesthetic part of your overall project. It will not assist in stabilizing any part of your tile. You should only be concerned about the color.

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  • kevin

    Long story I will try to keep short. I have done a number of tiling projects that have turned out well (with help from your website). However my latest project was a small area (50 sq ft) of polished black granite. Unfortunately I got some thinset on the face of the tile which I did not clean off quick enough resulting in etching of the polished finish…Can DIYer do anything to restore the finish, or should I just smash up and remove/replace the affected tiles? I have plenty of extra so that’s not a problem. They were set on Hardibacker, so if I were to remove them, do I need to remove all the dried thinset right down to the original backerboard?…..Thanks, Kevin.

    • Roger

      Hi Kevin,

      Replacing it is really the only option for someone without thousands of dollars worth of equipment. It would be best to remove all the thinset, but remove as much as you possibly can. It will be fine as long as it doesn’t cause the new tile to sit higher than the existing tiles.

      • kevin smith

        Ok thanks for that. but now that I have become emotionally scarred by this experience, I was wondering if useing a cement based grout could potententially have the same effect (ie etching the surface finish). Or if the grout is sponged off immediatly, is this a non issue?

        • Roger

          With granite it is not an issue. Regular cementitious grout will not etch the surface.

  • Alex Bowden

    With the help of your books, I have installed a preformed shower tray and Kerdi which I have sealed with silicone to the top of the shower tray.

    I have tiled over the membrane and grouted, except for the gap between the bottom row of files and the Kerdi on the top edge of the shower tray.

    I am now concerned about the best thing to do along that bottom gap between the bottom tile edge and the Kerdi which is sealed to the tray.

    Grout is assumed leak, otherwise we wouldn’t need the membrane.

    So water gets behind the tile, flows down the wall, and drains into the base.

    But if I grout the bottom gap, there is no guarantee that that grout will leak which could result in a back up of water behind the tile which will then drain sideways and ultimately find it’s way out at the ends of the shower, rather than draining into the shower tray.

    I’m sure that I’ve read something about this somewhere, but I can’t find it again.

    My Dog is threatening to combust unless he gets a shower soon.

    What is the best way to handle this?

    Thank you.

    • Roger

      Hi Alex,

      You install the floor tile and silicone between the floor tile and wall tile. You do not fill that entire gap, just enough to cover the joint, not all the way back to the kerdi.

  • Keith

    I am laying 6×48 woodlook tile throughout my home and the contractor is telling that I should not do 1/16” grout lines and to do 1/8” grout lines. I want to do 1/16” because it gives the tile more of true hardwood floors. Is there anything wrong with doing 1/16” grout lines with that size of tile?

    • Roger

      Hi Keith,

      It depends on how consistent and flat the tile is. Normally you need to do at least 1/8″ for tile that size, realistically, and technically, you should be using 3/16″ or larger. If you get a grout that matches the tile well it will still look like a wood floor. If you put a wood floor in it will look like a wood floor as well. :D I would go with the 1/8″.

  • Jeremy Miniard

    I tiled my shower floor using penny tile over Kerdi. If I were to use epoxy grout, is there any concern of moisture getting trapped between the grout and kerdi membrane and causing problems? Also, if I use regular grout is there a stain blocking additive you recommend?

    • Roger

      Hi Jeremy,

      No, provided your shower floor is sloped correctly any water will run down into the drain (even under the tile). There is no stain blocking additive that will be as good as a stain-resistant grout like TEC power grout or epoxy. Most that I’ve ever used are also inconsistent and a pain in the ass to work with.

  • byron

    I installed mosaic tile for a bathroom sink backsplash. Unfortunately about four little square pieces in various areas came off the sheet while installing. I added mortar to the back side of the squares and pushed them back in but they are either loose or fallen back out. Should I use an epoxy to get these to stay? Maybe using epoxy grout would be best and help repair these pieces.

    Also, I noticed Lowe’s no longer carries the Laticrete tiling products. Does Mapei have an equivalent to the Spectralock pro you recommend should I decide to use the epoxy grout?

    • Roger

      Hi Byron,

      Thinset should work fine to bond those tiles back in, but you can use epoxy if you want. Mapei has kerapoxy CQ, it is fairly easy to work with. Not as friendly as Spectralock, but just follow the directions and you’ll be fine.

      • byron

        The thinset worked to reset the small squares on the backsplash so all is good there. I have another issue with the shower floor. They are 2×2 squares but I turned them on point since I thought the cuts would work better around the edges since the shower is only 34×34″. However, the edge cuts are tiny rectangles and several of those came off the sheet while placing. I tried to reset them twice with thinset but they are too small to hold.

        So I decided to use this Gorilla adhesive that is waterproof to try and lock them down. Hopefully it’ll do the trick. Otherwise since these on on the edge next to the curb I’ll just grout them in as they will probably never get walked on.

        Even though we get pro advice some, like me, still end up doing an ameture job. Nothing like learning while doing.

        • Roger

          The glue is fine for those. If nothing else it’ll hold them in place until you get it grouted.