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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  • Michael

    Hello again dear fellow; I’m afraid I am not able to figure out where to get your reply to my Laticrete 317 question … the bag being open to the air and any moisture therein for several months … has that prolonged state impaired it in any way?

    … so where do I retrieve your reply? Nothing has come directly to my email either … sorry for the bother ol’bean … and many thanks for all you do for us amateurs …

  • David Squires

    Hi Floor elf, great website and stirling advice. You have saved me from making a few mistakes on my bathroom reno.
    My comment follows your advice on grout vs. caulk. I plan to use Dunlop colour matched caulk for the plane changes and grout between tiles. however I have installed carrara marble features at end of bath and in a shower alcove. So I have read that I should not use acetic caulk on carrara marble. And I cannot locate neutral cure caulk of the right colour. My proposed solution: use grout at all of the interfaces and plane changes surrounding the marble, and acetic cure caulk in the corners where tiles meet each other and the bath. I was meticulous while building the alcove etc so do not expect any movement to occur. If the grout cracks however, I may have to periodically re-grout. Do you have an alternative suggestion?

    • Roger

      Hi David,

      I would check out other manufacturers 100% silicone. See if you can find one that closely matches your grout, most of them have cross-reference numbers and match identically. If you find that use that for everything. Short of that your grout plan is likely your best bet.

      • David Squires

        OK found that Davco produces what I need, and a tile store selling it. Thanks Roger.

  • Mark Bugaliski


    Working on my bathroom Reno. I plan to extended the Hardiebacker board to cover the entire one wall to eliminate thickness difference, instead of transitioning to 1/2 inch drywall outside shower area. I am using the Kerdi membrane in the shower area and wondering how much the Kerdi membrane and thinset will build up the thickness compared to the Hardiebacker outside the shower area. I plan to tile across the entire wall from inside the shower out across the entire length of the wall, long rectangular tiles. I could guess the thickness build up to be 3/32 to 1/8 inch ? If so, will the tiles going over the transition have lippage issues? I read some where else to simply add more thinset to the tiles over the non Kerdi membrane area. Or do I shim the studs prior to installing backer board in area without the Kerdi membrane to even up the thickness?

    Another idea I had was to put a vertical metal transition strip where the Kerdi stops and start another complementary tile colour over the non Kerdi area.

    Appreciate your thoughts.



    • Roger

      Hi Mark,

      You are WAY overthinking this. :D Kerdi, with thinset, ends up at less than 1/16″. The MINIMUM trowel size you should be using on any tile is 1/4″. Absolute coverage with 1/4″ trowel will still leave 1/8″ of thinset beneath your tile – double the depth of installed kerdi. If moving from kerdi to non-kerdi on a single plane has lippage then the trowel you are using is not nearly large enough. No need to put more thinset behind the non-kerdi side, or any of the other stuff someone suggested. It should not be an issue at all.

      • Mark Bugaliski

        Sounds good Roger. I’ll do a little less thinking.



  • Vivian

    Roger, some of the grout came out on the corner and top edge of our shower bench seat (this shower was professionally installed) and water got beneath the bench. We didn’t notice it until water started seeping into the floor grout from under the bench and we stopped using the shower for a couple weeks or more to try and dry the water up. Now that the floor grout has dried out, can we just caulk the edge and corner of this bench, or do we have to tear out the bench seat to see if water (or hopefully not mold) is under that bench? Our installer moved away from our area, and now I’m wondering why he all of a sudden moved away after all the tile installations he did in our area.


    • Roger

      Hi Vivian,

      Unfortunately this happens a lot, and everyone thinks about it backwards. It is not the grout (or missing grout) that caused water to leak into your bench and swell the framing, it was the swelling of the framing that caused your grout to crack. Tile and grout are not waterproof. Your bench was not properly waterproofed before tile was installed.

      Water will get behind your tile and grout, it’s completely normal. If your shower is properly waterproofed there will be no issues. If it is not the water will get into your framing and begin to make it swell. Once that happens it will cause grout to crack (the first sign), tiles may become unbonded or crack as well.

      So the answer is no, you cannot caulk over it to fix it. Water will still get behind your tile. You need to remove the bench and see what type of waterproofing, if any, exists on your bench (and shower walls, for that matter). If it’s already cracking I guarantee you have we lumber beneath your bench, and it may already be growing mold.

      Sorry, I’m a frickin’ ray of sunshine this afternoon, huh? :D

  • Dave

    Ready to grout a shower. In the corners the depth is a 3/8 with a 3/16 grout line. 12 x 24 tiles. To use silicone, that seems too deep. Should I put in some more thin set and leave about 1/4″ room for a bead of silicone? Using Mapei grout and there matching silicone. I did put it around 2 granite shelfs in corners, and it was not so easy to get a nice line. Had to clean up with acetone on top of the tiles were it smeared some.

    • Roger

      Hi Dave,

      You have 3/16″ gaps in the corners? That’s excessive. However, do not use mortar, get some backer rod and stuff in there. It’s just cylindrical foam that will fill most of that gap up, you silicone right over it.

  • Bob


    I have removed all the grout from the corners, etc and I have one last question. Granted, I have used caulk before, including building an aquarium. That is where my question comes in.
    As I stated above, I have a space between the wall and floor in my shower. I will be using backer rod to fill in the area behind where the caulk will go. Now, thinking back to when I built an aquarium, there was no space between the sheets of glass and the caulk basically was adhering to the inside face of the glass pieces. It really didn’t go inside the crack between the pieces of glass. (I hope that makes sense!!!)

    So, when caulking the tile in the shower, I realize the caulk will be going into the void between the wall and floor but am I am also wanting it to go up on the wall tile and out on the floor tile, similar to how it did on the aquarium? The reason I am asking is if it does, it seems it would be susceptible to coming loose ever time the shower is cleaned and the line between the caulk and tile would get dirty. Again, like in an aquarium.

    • Roger

      Hi Bob,

      As much as possible you only want the silicone in the gap, ideally flush with the face of the tile. You’ll have a tiny bit of the bead that will adhere to the face of the tile, but you don’t want it anything like an aquarium corner.

  • Brandon W

    I have a rental unit with a 3×3 tiled shower, walls and floor, pan has started to leak and I will be repairing this next week, considering replacing this mortar and tile shower floor with a fiberglass pan, are there any issues that I may run into while converting this floor, should I stick with original design and just repair the liner, mortar, and re-tile? Thanks for any advice.

    • Roger

      Hi Brandon,

      I would likely replace it with the acrylic pan if I were you. Repairing a leaking shower floor is rarely a simple repair, and more often than not requires replacing the entire floor. The only real issue you may run into is drain pipe size, but there are couplings to get you to the correct size if it is not.

  • Bob


    I am getting ready to grout an area that I replaced the tiles in and I am planning on leaving the “change of plane” corners, etc grout free so I can silicone them. any tips on how to grout right up to the corners without grouting the corners? I am using 2×2 slate tiles and there will be several ground lines leading into the corners, if that make since? It seems to get the gout lines between tiles finished properly, grout is going to get into the corner to.

    • Roger

      Hi Bob,

      Grout will get into the corner. Just grout as normal, don’t worry about the grout in the corners, clean it up and right after you’re finished wiping run a utility knife down the corner to remove the grout (a hooked dental pick works best), just be careful not to damage your waterproofing if you’re using a topical method.

  • Andy

    Tiling a tub surround, if I was to grout between tub and bottom of tile.
    Should I first fill tub ?
    Also what size gap would you advise?
    Would prefer to use sanded grout.
    Thanks for any advice and appreciate you site.

    • Roger

      Hi Andy,

      The answer to none of those questions will matter. What matters is IF you put grout between your tub and tile the grout WILL begin to crack and fall out. They are two different materials (ceramic and acrylic) and they WILL expand and contract at different rates. Silicone will compensate for the – grout absolutely will not.

  • Tom

    Good afternoon,
    Love your site, great job. Two years ago I followed your tutorial on building a shower floor, then tiled it with river rock type tile. The walls are also tiled. Anyways, given it was my first time, it did not come out perfect. There are gaps between the wall and the floor that range from 1/8″ up to 3/4″. I caulked this gap first time around. When I went to replace the caulk this weekend I ran in to some issues (at least I think they’re issues). There are spots that the caulk failed and the water eroded away the concrete a little bit. I’m sure if it went longer it would have gotten much worse. Here is my question, I’m between simply recaulking, and doing so annually therefater (it takes about 2 tubes of caulk though) or installing a row of some sort of tile trim to cover the hole, then grout and caulk that as appropriate. What are your thoughts?

    • Roger

      Hi Tom,

      What I would do is clean everything out, then run a bead of silicone (a regular size bead) along the floor under the wall. It doesn’t need to touch the wall tile. Then, once that’s cured, grout between the tile and silicone. Then you have a proper bead of silicone, that isn’t huge, and replacing it is just a regular size bead (not 2 tubes).

  • Ken

    I was chatting with a tiling contractor I met at Home Depot and asked him about silicone caulking the bottom row of tiles where it meets the shower pan or tub. There is a 1/8 to 3/16 gap between the tub and the tiles and the concrete board also has a similar gap which was caulked with silicone. There is also the 1/2 inch or so lip of the shower pan behind that. He asked why not just leave that bottom row uncaulked or ungrouted. The chances of water wicking up on the concrete board are very slim. Any water that does will dry out and have a space to exit if uncaulked. Seems logical to me but what are the hazards of not caulking this space.

    • Roger

      Hi Ken,

      There are no hazards at all, provided you regularly clean UP UNDER the bottom row of tile. Otherwise all sorts of neat stuff can grow in there. Be best option, in my opinion, is to fill the bulk of those spaces with backer rod (it’s cylindrical foam) and silicone over it making sure to leave weep holes. But it doesn’t NEED to be caulked.

  • Tristan

    I am a DIY-er tiling my shower surround. I would like to caulk the corners and shower-tub joint, but the only matching caulk I can find is sanded which I bought for the floor. The grout for the shower is unsanded. Can I use the sanded caulk for the shower? The store apparently doesn’t carry my grout color in an unsanded caulk.


    • Roger

      Hi Tristan,

      Yes, you can use that in the shower as well.

  • B.

    I have a newly renovated (less than a month) tiled shower. There is a hairline fracture in the sanded grout on the bottom of the shower wall. The contractor says that the best repair is to put a sanded silicone grout caulk on top of the crack. Shouldn’t the cracked grout be taken out before applying the silicone grout caulk? Is the silicone grout caulk the best solution (or the easiest for the tile person) or would re-grouting that little corner? Am anxious to seal the shower but want this grout properly corrected before it is sealed.

    • Roger

      Hi B,

      If it is at the change of plane then ALL of the grout, at any change of plane, should be removed and replaced with silicone or caulk. It can compensate for the movement, grout can not (as you now know :D ).

  • Jodi

    We have a shower only with tiled walls and floor. Some of the grout on the edge (where tile floor meets tiled wall) has started to come out. Do we need to remove all old grout and then regrout and then caulk over? My husband wants to caulk over, but I’m unsure of which product would be best. What is your suggestion? Another issue is the grout on the floor is a dark brown and grout on the walls is white. Thanks for the help!

    • Roger

      Hi Jodi,

      That is a change of plane and it needs caulk or silicone in it, not grout. Grout will ALWAYS crack there, whether you have caulk over it or not. Dig out the grout and silicone it.

      • Jodi

        Ok thanks for the help. They don’t make a color silicone that matches our grout. Right
        Next to the silicone they have colored unsanded grout caulk that matches. Could I use that instead? Or stick with the silicone?

        • Roger

          Yes, you can use that.

  • Paul

    Just need some clarification. Do you recommend grouting the field area first of a shower enclosure and then caulking the corners and bottom where the tile meets the shower pan after the grout? Do you recommend silicone or caulking? Thank you


    • Roger

      Hi Paul,

      I always recommend silicone. You can do it in either order, I normally silicone after I grout.

  • Bob

    I am in the process of removing the cracked grout out of our shower stall corners (wall to floor) and was thinking about using caulk to replace it. The only issue I see is when it was installed, the builder/prior homeowner left about a 1/8″ to 1/4″ gap (maybe even 3/8″ in places) between the wall tiles and the floor.

    Doesn’t this seem like a rather large void to fill with caulk?

    • Roger

      Hi Bob,

      Yes it is. Just use backer rod in it first. It’s just cylindrical foam you stuff in there then silicone over. The foam takes up the majority of the gap.

      • Bob

        Thanks Roger

        I was already planning on using backer rod. I was just worried about the integrity of the caulk spanning such a large “void” even with backer rod behind it.

        • Roger

          I’ve never had any problems with it at all, even on the worst gaps.

  • Zach

    I have a question regarding spectra lock pro premium for use in change of planes. I have been reading on this topic and heard all different responses. I have read and heard plenty of stories of people using spectra lock in changes of planes and it cracking within a few months.

    Then everything I hear about caulks or silicone caulks are that they mold and mildew.

    I would really prefer to use spectra lock everywhere but don’t want it to crack and have to scrape it out. Have you ever heard of spectra lock cracking in corners or where walls meet floors?

    If I were to use caulk is there one that won’t mildew ad miscolor? Thanks!

    • Roger

      Hi Zach,

      Yes, it will crack when the walls expand and contract – which they will. Properly maintained caulk or silicone will not mold or mildew. The biggest issue is that people think caulk and silicone are permanent products – they aren’t, they are products meant to be a part of regular maintenance. That includes removing and replacing it every 5-7 years. Once the product loses it’s elasticity and becomes unbonded from the tile water will get in there, as well as all sorts of nasty stuff that can’t be cleaned out, and mold may begin to grow. Once you realize it is not a permanent product, and get a regular maintenance regimen in place it won’t be an issue at all. It’s not the product that’s wrong, it’s people’s perception of it’s use.

  • Goodnightjohnboy

    What’s up elf, I just got done with master bath floor & shower. I used urethane grout (which was a royal PITA) for the whole thing. I’ve read the claims about how urethane grout is water resistant and you don’t have to seal it & its supposedly stain proof. I still want to silicone all corners, but is the urethane sufficient enough to keep water out & will it crack like cementious grout? Are all the claims true?

    • Roger

      Hi John (I’m assuming, here…),

      Urethane grout is waterproof, and fairly stainproof. You are correct, you still need to silicone all changes of plane. However, I’m hoping that your shower floor and wall substrates were properly waterproofed before you installed tile? Because tile is not waterproof. No, it won’t crack like cementitious grout.

  • Inna

    Hello Roger,

    My contractor installed caulk over grout at the gap between tub and tile walls. The caulk failed and I am currently removing the existing caulk to reinstall. Should I also scrape the grout? Is it possible that one of the reasons the caulk is peeling is because it was adhered to grout?

    Thank you in advance.

    • Roger

      Hi Inna,

      Yes, you should also scrape out the grout. It failed because there was grout in the corner to begin with, it will always crack, which causes anything over it to fail as well.


    Hey Roger,

    I always enjoy reading what you have to share about peoples questions. What do you think about the kerdi tile-to-tub-profiles instead of grout or caulk (for b/w tub and wall tile. I was just wondering if it will work just as good or not. If not I dont do use thr trim I would silicone caulk that gap between the tile and the tub.

    • Roger

      Hi Zack,

      I like them. They work very well, but they are a bit spendy.

  • Marc

    Hi Roger,
    I plan on using caulk in all corners as you recommend. The problem I have is my local tile store where i purchased the tile is trying to sell me Bostik grout and the matching caulk. Which would be find except I will be using a sanded grout but Bostik doesnt make a sanded caulk like other companies do.
    Should I just buy the matching grout and caulk elswhere or is the fact that the caulk won’t be sanded not a big deal. I’m afraid it will be noticably different from the sanded grout.

    • Roger

      Hi Marc,

      It likely will be fairly noticeable. You may want to look for alternatives.

  • Val

    How to remove e-mail address after leaving a comment

    • Roger

      Hi Val,

      There is ALWAYS an unsubscribe link at the bottom of EVERY email sent from my site. Just click on that.

  • Val

    Hi Rodger,
    Sorry to bother you at this time.
    I have shower floor remodeled by professional contractor. After a couple of months I have found that in one place between wall and floor about 2 ” caulking
    start pilled out. I ‘ve cleaned it ( have found that this caulking was put on the depth about 3/4″). I put in Silicone II caulking, but it doesn’t solidified (probably was too old). How can I clean it? Which type of silicone would be the best?
    Thank you and have a happy New year.

    • Roger

      Hi Val,

      Wipe it out the best you can and get some silicone solvent or cleaner (paint department). Any fresh silicone will work fine. Your room also needs to be above a certain temperature to be able to cure correctly (it’s listed on the silicone tube).

  • Nick

    What do you think about these two strategies?

    If I’m unhappy with the grout, because it cracks out, I can remove it and install caulk…

    If I’m unhappy with the caulk, because it gets moldy or peels off, I can remove it and install grout.

    Are both these strategies feasible or recommended?

    • Roger

      Hi Nick,

      You can do whichever you wish. I’m just stating what the best practices are to eliminate as many problems as possible. Caulk will eventually become unbonded, it is intended to be a regularly maintained product. That’s why silicone is better, it won’t lose elasticity as quickly and will last longer than regular caulk before it needs to be replaced.

  • Jason

    Hi Roger. I have a 20 yr old tiled walk in shower (with a steam unit as well). The tiles are all approx 1.5 inch sq. There is a 20″ tiled seat built in. At the front edge of seat, about half the tiles lifted up when I scraped the front joining edge to regrout. Can I use thunder to affix them, then use sanded grout to fill the approx 1/16″ spaces, let dry, then use 100 percent clear silicone sealant over all the grout lines? I do not care about the aesthetics, just do not want water on ceiling below as happened previously?

    Also, please tell me how I can clean up old silicone now in corners? or can I apply new silicone right on top of old stuff? Many thanks. Jason

    • Roger

      Hi Jason,

      That is indicative of water intrusion into your bench. You can use thinset to rebond them, but it doesn’t solve the problem and there is no way to waterproof over tile (silicone will not work). Unfortunately your bench will likely need to be rebuilt and properly waterproofed to guarantee no water where you don’t want it.

      You can either scrape the old silicone out or use a silicone remover (it’s a liquid sold in the paint department). You do not want to go over the old stuff.