One of the most asked questions by do-it-yourselfer’s is whether they should use caulk or grout in the corners. Industry standards state that a flexible material be used at all changes of plane. But! – if you ask a hundred different professionals you will more than likely receive fifty of each answer.  While there are pros and cons of each, I am in the camp that uses caulk. That being the case, I will discuss using grout first. I’m backwards like that.

Using Grout at Changes of Plane

While the phrase “changes of plane” may sound a bit uppity or technical – it’s not. It simply describes the corner or edge of any surface that changes direction such as a corner, a wall to a floor, or a wall to the tub edge. Many professionals simply grout that corner as they do any other space between the tiles. There are a couple of things that must be taken into consideration before choosing this method.

  1. Your walls and the framing of your shower must be absolutely rock solid. I do mean absolutely. Grout is a cement-based product and as such is not meant to flex. If your wall moves your grout will eventually crack – it’s that simple.
  2. The space between the tiles at the change of plane must be large enough (for sanded grout) or small enough (for non-sanded grout) to be able to support the grout. That simply means that if you are using sanded grout you cannot butt the tiles against each other at the corner and expect to be able to force grout into it. It will not stay if the grout has no grout line to hold onto – if it is simply attempting to grab onto the face of the tiles at a 90 degree angle. There must be a grout line at the changes of plane.
  3. You must decide you are going to use grout at the changes of plane before you install the tile. You can then make sure to leave a line for the grout as well as adding additional support for any spots that may move even the tiniest bit (which it should not do anyway).

If you have taken the above points into consideration and still decide to use grout in the corners – go ahead. The big advantages of using grout here is that it will match all the grout lines and it will never have to be replaced. So although extra care must be taken to properly use grout at your plane changes, the advantages for some people are worth the extra time.

Using Caulk at Changes of Plane

There are several advantages to using caulk in corners and any other area where there may be a plane change or where tile meets another material such as your bathtub or sink.

  1. Unlike grout you are able to use caulk in a corner where tiles are butted against each other. It will stick to the face of the tile rather than needing a space between the tiles to grab.
  2. Caulk is flexible. If there is any movement the caulk is flexible enough to move with it and remain in place. It will not crack out or fall off.
  3. Caulk is waterproof – grout is not. Water will collect in corners such as where your tile meets the tub more than it will on the face of the tile.
  4. If your caulk does crack out or need to be replaced it is easily done.

The only two disadvantages to using caulk instead of grout are that you need to periodically remove and replace the caulk and, depending on your choice of grout, you may not be able to find a caulk that matches exactly. The first reason I consider to simply be regular maintenance and the latter is less of a problem since most major grout manufacturers sell matching caulk.

When to Use Grout

The only time I will use grout for a plane change is when I am using epoxy grout. Epoxy grout is bulletproof! OK, maybe it’s not bulletproof but you can hit it with a hammer a couple of times before it chips. (Don’t do that.) If you are using epoxy go ahead and grout the corners and changes of plane as well. Although it is not flexible it will grab the tile well enough to prevent it from splitting or cracking out. Precautions must still be taken but the Epoxy is strong enough to withstand normal structural movement.

How to Decide

Given the above parameters I believe caulk to always be the best choice. What you must understand about tile installation is no matter where you are installing the tile, it is always a structure that moves, no matter how minutely. Concrete moves, (the ground beneath it) that’s why it has expansion joints – to control where the movement goes. Most shower installations are over a wood structure of some sort. Whether you have drywall, backerboard, or a membrane, if you go far enough behind the tile, you’ll find wood. Wood moves, it’s just a fact of life. Humidity, weather, even the structure’s foundation all affect how much it moves. By taking proper precautions you can minimize the movement, but it’s still gonna move. Taking structural movement into consideration caulk is, for me, the logical choice.

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  • Sarkis

    Hi Roger,
    Thanks for your article. I am doing porcelain tiles on the wall which is thick rough cut wood and pebble tile on the floor which is concrete. I am expecting some larger gaps around the wall between the pebbles as I am not using any small ones to fill the gaps. So my question is, if I just use caulk (NovaLink 35 concrete masonry sealant) will that hold with those gaps or should I grout close to the wall but leave a gap and fill it with caulk?


    • Roger

      Hi Sarkis,

      You should place a bead of sealant or silicone around the perimeter of the wall at the floor, let that cure, then grout up to the bead of sealant. That way you have a consistent bead of sealant between your grout and wall. Caulk first.

  • steven

    Hi Rodger, I have a plank wall which I recently uncovered when I removed the old beaver board, the planks are mismatched in width from 18″ to 21″ . The wood seems to be old growth spruce due to it’s dark brown/ red coloring and the smell. The gaps between planks range from a 1/4 to 3/8. The mud sills and girder have just been replaced with steel and anchored to concrete piers which were poured below the frost line, so the structure has been stabilized, the inside temp of the structure as a range of -45 to 100 degrees F. I would like to fill the gaps and use the wall as an accent wall while maintain an authentic old pioneer look. could you offer any suggestion?

    • Roger

      Hi Stephen,

      I really don’t know much about the stability of products used in that type of installation. You’ll get much better answers from a woodworking forum of some sort.

  • Jason

    What about windows in the shower? The are high enough that they will only get shower spray but will get water on them. Do I need to caulk where the wall makes a 90 degree turn into the window? The outside edge if that makes sense.

    • Roger

      Hi Jason,

      Yes, everything around a window needs to be siliconed. It is imperative, that is one of the biggest failure areas in any shower.

  • John Huenneke

    first a question. I am renewing my shower, sanded caulk on plane change and cleaning surface of tile from 12 years of calcium buildup. I have a few tiles which lost grout on walls about 1 inch long. Should I just fill with caulk as space between is very close “max 1/16 inch? While looking at your site when I saw your picture my mouth kind of dropped open and my attached photo of my son will tell you why. Kind of eerie.

    • Roger

      Hi John,

      You’re a good lookin’ guy. :D You can fill them with caulk, but grout (of course) would be better.

  • Jeff martin

    Hello, learned a lot from this page. Question is referring to grouting before or after caulking corners. If I caulk the corners or change of plane, wait a day, then grout the rest of shower, will the grout that meets the corners seal correctly to the caulk. I’m worried about later on when flexing occurs at change of plane, the caulk should be fine, but each row of grout line where grout meets caulk.

    • Roger

      Hi Jeff,

      I’ve never seen, nor heard, of any problems with that. It’s actually the recommended way to do it, I just don’t have time to wait to do it that way.

  • Amanda

    Hi, I’m having mixed feelings about the grout in my shower corners. We just installed an acrylic shower base with tiled walls. We had a contractor fram in new bathroom walls around the shower. Cement board for the backer with corners and seems with tape and mud. I did the tiling myself from learning on here, but then my brother came to help me grout. My dad was a carpenter and my brother worked with him on many jobs. So when he said to put grout in the wall corners I did question it at the time. Of course, last night laying awake worrying that everything was done right I came to your website. Question now is; do I try and get the grout out of the corners right away and fill with silicone. Or should I seal grout and wait to see if it holds up?

    • Roger

      Hi Amanda,

      Although it isn’t correct – it isn’t going to compromise anything in your shower. Nothing’s gonna get hurt if it fails. I would remove it now and replace it with silicone, but you can seal everything and see if it holds up. It may work, it may not. But if it doesn’t you can always replace it at that time.

      • Amanda

        Thanks so much for responding right away, and sharing your “passion” with us DIYers. :)

  • Nick

    Hi Roger
    I’ve learned so much from reading your posts—Thank you !!
    I do have a couple of questions–1. In the shower, I know you should silicone the backerboard at all plane changes, but do you tape and thinset them after the silicone dries? 2. Is it necessary for bathroom floor underlayment (3/4″ plywood screwed to floor joists) to have 1/16-1/8″ gaps between them, just as you would for the cementboard that will cover them?
    Thanks for your time—it’s much appreciated.

    • Roger

      Hi Nick,

      1. Yes, I do.
      2. Yes, with either tape over the seams or silicone in them to prevent thinset from entering them as you install your backer.

  • Richard

    One small (possibly dumb) question, which I may have missed in the original article…
    If using caulk in the edges and corner seams, should it be applied before or after the grout is applied to the rest of the tiled surface? Thanks for all your valuable info!

    • Roger

      Hi Richard,

      No a dumb question at all. TECHNICALLY it should be installed before the grout. That ensures that you don’t have any grout in those lines and they get filled with silicone. That said – I do it after, I simply dig out the grout before it fully cures. The reason I do it that way is time. The silicone has to cure before you grout. I can’t silicone then wait a day to grout. It can be done either way provided you keep the grout out of those lines if you grout first.

  • Nubia

    About 8 weeks ago the super grouted the tiles around the bathtub and it has been building mold, could you explain the reason why is this happening, the rest of the tiles in the bathroom are in perfect condition. Thanks.

    • Roger

      Hi Nubia,

      Your tile isn’t growing the mold – the substrate beneath the tile, which is likely plain wood, is the issue. It’s likely soaked and feeding mold. Regrouting it will not solve the problem. It needs to be replaced.

  • Dave

    Your advise has been a Godsend! Saved me more times than I can count. Here’s my issue. Being a DIY guy (for me) means Doing In Your own time. Thus I started my shower remodel a year ago. We have a hall bath for a reason ya know! I have 2 rediniches in my new shower. The caulk I used where there was a change of plane in the niches has never cured. The other caulk I used all cured. There was plenty of time for the thin set to cure behind the tiled parts of the niche, months (a year remember?) in fact. Bad caulk? Bad install? Bad ????

    • Roger

      Hi Dave,

      It sounds like an issue with the caulk itself. There is little (if anything) you could do to cause caulk NOT to cure.

  • Peggy

    Why new shower tiles cracking? What tool is used to remove sanded grout from the tiles? Sanded grout was used in corners and between the tile.

    • Roger

      Hi Peggy,

      If it’s unsanded grout it may just be shrinking, which means the incorrect type of grout was used. If it is sanded grout then it’s cracking because you have movement in your tile or substrate – something wasn’t installed correctly. Read through this for specifics on removing grout: Regrouting tile

  • Rick

    Your information and manuals have been invaluable to my tile job! Thank you for such great information!!

    Question: My grout manufacturer (Tec) has a color matched siliconized acrylic caulk. Sanded and un-sanded versions. Is this a quality product or do I need to use “true” silicone? Is Earthmaster Color matching system worth the effort?

    Thank you!!

    • Roger

      Hi Rick,

      Earthmaster is a great product. However, Tec also has matching 100% silicone for all of their grout colors. If your supplier doesn’t carry it you can order it online. That is actually the brand that I use every day – it’s great stuff.

  • Singh

    How do you define ‘corners’? Are we talking about caulk on the entire perimeter of the tile floor (wherever it butts up against drywall or some other structure?) or is it literally just the four corners of a square tile floor? Just wondering because it’s not intuitive to me where to use caulk.

    • Roger

      Hi Singh,

      Any change of plane. Anywhere a wall (or floor) changes directions. Such as where the side wall meets the back wall – that entire angle from the floor to the ceiling should have silicone in it.

  • Melanie

    Hi Roger,
    We have installed a 12 x 24 porcelain tile with 1/16 space between tiles in our Kitchen floor. And I’m embarrassed to say that I mistaking used caulk instead of grout. Do I absolutely have to scrape it out and re-do it with grout? Or will the caulk be okay for the Kitchen floor with the small spaces between tiles?

    Also, we have a wood subfloor, and we did install the hardboard etc.

    Any advice would be appreciated.


    • Roger

      Hi Melanie,

      You can remove and replace it now, or you can wait until the seal breaks after the caulk shrinks and stuff starts growing out of it. I would do it now. :D

      Do you mean you installed the tile directly over the bare plywood subfloor?

  • Tina

    Hi, I am in need of recaulking a walk in shower where the floor meets the wall. However, I am unsure about where wall meets wall, should I be recaulking this as well or is that grout that needs to be used when a wall meets a wall? There is about couple inches off the floor in the corners that look dingy that could be replaced. Thank you. Tina

    • Roger

      Hi Tina,

      Yes, where the wall meets the wall also. Any and all changes of plane should be caulked or siliconed.

  • Andrew

    Hi Roger,

    I’m at the point in my bathroom renovation where I need to caulk the changes of plane in my shower and the drain, but I’m having a difficult time selecting the right type of product—100% silicone (Latisil), or their unsanded or sanded siliconized acrylic latex.

    I’ve left a 1/8″ gap between tile at all changes of plane (except where the shower wall tile meets the 1″ hex on the floor—it’s more like a 1/16″ gap here), as this matches the width of the grout lines. The tile I used is a white matte subway tile with sterling silver Permacolor grout.

    I picked up some color matched Latisil and started using it in a few inconspicuous places outside the shower (where the curb meets the bathroom floor, and where the floor tile meets the marble threshold between bedroom and bathroom). I wasn’t happy with the wet look of the 100% silicone Latisil when all my tile and grout have a dull/matte appearance.

    Do you have any advice/experience with using unsanded or sanded siliconized acrylic latex caulk inside a fully tiled shower? For purely aesthetic reasons, I want to believe it will hold up fine, but is Latisil a far superior product to use in this application? I’m concerned that the shiny/wet caulk lines will be an eyesore! But, I’m also wondering if I’d be sacrificing too much quality by going with a sanded or unsanded siliconized acrylic latex. Thoughts?

    Also, do you have a preference towards caulk or grout around corner shelves (I followed your advice in another article on making corner shelves out of tile; worked great by the way)?

    I’ve appreciated your time and advice throughout this project. Hard to believe it’s almost finished!



  • Matt

    Hi Roger,

    I am doing a walk-in shower in the basement. So instead of having a curb, the floor will run straight into the shower from the bathroom floor. I am planning on using the liquid topical waterproofing. I am guessing I will need to run the topical waterproofing into the bathroom floor area as well (at least a little ways) What is your suggesting for waterproofing this type of shower floor?

  • Rose

    Hi, can you please help me? I have some leaking going on underneath my shower and I think it might be caused from grout decayal outside the shower. Is there a way to regrout, caulk and then put sealant on? Would that help eliminate the problem?

  • Gilbert Lee

    We have very hard water in Tucson, Az. Do you know the best way/product to clean the minerals from the tile. Is there anything to apply that will prevent minerals from sticking?

    • Roger

      Hi Gilbert,

      An efflorescence cleaner will take the minerals off. Any really good sealer will allow you to simply wipe off the minerals with a wet towel rather than bonding to the tile.

  • Richard

    My show sprays directly at the corner where the pan meets the wall. Grout and caulk both wash out in a matter of weeks. The gap between the tiles at the edge of the pan and the wall is uneven but the sanded grout washes out at the wide spot where it should be able to get a good hold. Poly caulk holds but washes away under the direct spray. It am thinking about widening the gap with a Dremel and using grout again but I don’t expect it to work. Can I glue a quarter piece of tile in the corner and caulk the small seams around it?

    • Roger

      Hi Richard,

      Use 100% silicone and give it a full day to cure, that will solve your problem.

  • Cathy

    Hi – we just had our bathroom remodeled with the shower walls tiled and grouted. A month into it we found that the grout in one of the shower corners were cracked. The tile installer came out to fix the issue by applying a clear silicone sealer in every corner of the shower instead of re-grouting the cracked grout in the corner. After reading the article above, perhaps this was the ideal method since we may have faced the grout cracking again in the future. I’d like to get your opinion – what was the best way to fix this grout crack? Thanks for any feedback!

    • Roger

      Hi Cathy,

      The best, and proper way to fix it would have been to remove all the grout in the changes of plane and replace it with silicone.

  • Robert Tucker

    I’m tiling a walk in shower with 2 foot horizontal by 1 foot vertical tiles on the walls. The floor will be 2 in by 2 in tiles in 1 foot square mats. Have read your grout vs. calk comments and still have a question. I am planning on using epoxy grout for the grout lines. Can I use calk at the changes of plane or would it be better to use the expoxy?

    • Roger

      Hi Robert,

      It would be best to use silicone.

  • Jeanie

    The joint between floor and wall WAS grout. It has cracked. I am removing it and plan to caulk instead. I also want to clean the grout on the shower floor. Should I clean and caulk first then do the floor, or should I do the floor then clean out the “new plane” grout and caulk?

    • Roger

      Hi Jeanie,

      I would scrape it all out, clean, then caulk everything.

      • Jeanie

        Do I need to worry about water getting into the crack at the change of plane when I clean the shower floor tile? Also, does ALL the grout have to be cleaned out before I caulk, or will the caulk forgive me for some remnants of the grout?
        Thanks for your answer, by the way.

        • Roger

          Hi Jeanie,

          You need to get as much out of there as you can. Provided your shower is properly waterproofed no, you don’t need to worry about water getting in there. It does need to be dry before you silicone it, though.

  • Larry Stringfield

    In reading thru your waterproofing book you use fat mud for the curb. Why not just cover it with backerboard?

    • Roger

      Hi Larry,

      Because there is no way to attach it without puncturing your membrane.

  • Buffy

    So maybe I am over thinking this issue, but I am cornerhoping you can advise. We are in the midst of a bathroom reno. I have tiled areas around our home before, but am not confident to make cuts to tile around plumbing etc so we are having someone install tile in the tub area. I know enough that at corners, i.e. change of plane, caulking is generally used to allow for movement, and I suspect that this old house will move inspite of my husbands efforts to make things sound in this area. The installer seemed unfamiliar with this tactic, and I will show him some info before he works here for us. But what I am wondering about is the gap that should be left between the tiles where they meet at the corner. We are using 2ft x 1ft tiles, 3/8 inch thick and I have asked for a small grout line to make grout less noticeable. Should the tiles be cut a length that will allow for a gap at the corner where they meet that will be equal to the grout lines elsewhere? Or do the tiles butt up in the corner and the silicone caulk just goes on top? They are a high gloss tile, so I think this would cause adherence issues? Thanks for your help! I have already learned a lot by following your posts!

    • Roger

      Hi Buffy,

      I leave about 1/16″ – 1/8″ gap in the corners for silicone.