Caulk or Grout in Corners?

by Roger

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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Denise

My shower has 12×12 inch tiled walls and 2×2 inch tiled floor. The whole shower was grouted with color sanded grout. Is it okay to put clear silicone caulk where the floor meets the walls (change of planes) on top of the grout?

Reply

Roger

Hi Denise,

It will be fine initially, but if the grout begins to crack it will still do that beneath the silicone, then it’s a hell of a mess to clean up. It would be better to remove the grout in the corners then use just silicone there as it should be.

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Ben

So…shower wall of traditional lath/mortar, using a 12×24 porcelain tile. I’m thinking 1/8″ grout lines, using unsanded polymer-modfied grout which (may or may not) be called Polyblend and (may or may not) be from a big box store… Sounds appropriate or more worthy of a jackassery award?

Sub-question: Same style grout for a tumbled river rock floor of the traditional shower pan?

Thanks in advance! :D

Reply

Roger

Hi Ben,

I would use sanded grout for both of those (whether or not it’s called polyblend :D )

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Chad Miller

Roger thanks for answering my last question so fast. Love all your information on this website. I’m ready to grout my 12×12 tiles but I don’t know for sure what grout to use. I understand everything you are saying about grout but what the store sent with me and what you say about sanded and unsanded I have the wrong grout and I live 3 hours from the store. Here is my deal on my shower. 12×12 tiles on walls with 1/8″ grout line, 2×2 tiles with 3/16 grout line on floor and a strip of mosaic tile around on walls. The store sent unsanded Mapei grout and liquid Grout Boost to mix with the grout instead of water. And also Mapei unsanded caulking. So what I understand from what you are saying I should use unsanded on the mosaics and sanded on the rest of grout lines? Is Mapei grout a good grout or should I get a different brand if I need to get sanded grout? Is Grout Boost just for stain proof or is it a sealer also? And I know I should use silicone instead of caulk but do you usually use clear or white silicone(our grout color right now is Chamois unless I go to different brand).
Thanks again in advance. Sorry so long but just want to get it right so I don’t have to do it again in few years and really don’t want to drive 3 hours to get different grout(wish I would of found your site before I started this project)!!!!

Reply

Roger

Hi Chad,

I would use sanded grout for all of it. Grout boost is a sealer, a sealer is for stain proof, so both. :) Mapei is a very good grout. I normally use a silicone that matches the grout color. Mapei makes silicones that match their grout color as well.

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Chad Miller

I am new at this tiling and I have learned a lot from your site. I finished tiling my shower walls and floor. On the shower wall corners I tried to leave 1/8″ grout line (sometimes was little less or more) and used 12″x12″ tiles. I am using Mapei unsanded grout and bought the Mapei unsanded caulk to match the color. My question is will this caulk work for the change of plane or should I be using silicone?
My other question is I put a bench in the shower also and on the front of the bench where the top of it meets the front side of bench(change of plane) I left a grout line there also(maybe should of butted it together?). Should I grout or caulk that change of plane?
Thank you

Reply

Roger

Hi Chad,

The caulk will work, but silicone would be better. All sealing products (caulk, silicone, etc.) tend to lose elasticity over time and need to be replaced, silicone lasts the longest.

Grout the line at the front of your bench.

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Devi Morgan

Roger,
We are tiling a custom shower in our new construction home. I read your post about using caulk/silicone in all change of plane areas. My question is where do you purchase the caulk/silicone that you use/recommend? We only have the usual home improvement stores here, Home Depot and Lowe’s. Also is it caulk or silicone? I’ve researched what’s available at these places and there seems to be a sanded grout caulk and a silicone. Both of which can be color matched. We don’t want a shiny look to it but will chose so if it is recommended. We are using 12 x 24 tiles vertically. We laid the tile on the floor already and did a 1/16″ grout line. Personally we like it better than a 1/4″ grout line. What do you recommend for the shower? Can it be personal preference or does it need to be a certain size for a reason? Thanks for your advice!

Reply

Roger

Hi Devi,

I have a Florida Tile, Dal Tile and flooring supply shop here locally, I can get what I need from one of the three. I would recommend silicone, some HD’s carry custom’s silicone, some don’t. If they don’t you can order it online at amazon or go to color-rite and order one from them.

For the most part grout line size is personal choice provided the tile allows for it. I use 1/16″ on most walls and 1/8″ on most floors. The absolute largest I’ll do is 3/16″ on floors, and I haven’t done that in seven years.

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Abed

Great site.
My question is:
By caulk you mean 100% silicone or sanded tile caulk ?

Reply

Roger

Hi Abed,

Either one. Silicone is obviously best, but can sometimes be difficult to find in the correct color. Sanded caulk works, but loses it’s elasticity much more quickly than silicone, so needs to be replaced sooner.

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Mark S

Hi Roger,

great site, great info! I want to make sure I understand you, though.

I have a 2.5 year old shower that was done with carrera marble and unsanded grout, even at the change of planes. My big issue is the space between the floor (a solid slab of marble) and the walls (marble tiles).

The grout does not meet the surface of the tiles and I am seeing discoloration of the wall tiles in the corner nearest the drain, which is the are where water pools the most… the slab is not quite as level as one would hope it to be. I assume that tile is absorbing this water and that there may be cracks in the grout as well, as the joint varies from 1/4″ to 1/16″.

Rather than regrout, I understand you to believe that removing the grout and replacing it with silicone to be a better choice. Do I understand you correctly?

Thanks so much!

Reply

Roger

Hi Mark,

That is correct. Any change of plane should have silicone in them rather than grout.

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Mark S

thanks a million! we all appreciate your generous advice.

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patrick

Hi Roger, I am seriously considering using 100% silicone for my shower walls (Commercial color grade 100% silicone http://www.homedepot.com/p/Custom-Building-Products-Commercial-186-Khaki-10-1-oz-Silicone-Caulk-CCSC186/205939348 ). I do understand that it is a bit of extra work, and more expensive but I did some testing and it seems like it will work fine, for my little projects I don’t care the extra expense.

It matches the colors I want, it is 100% waterproof and (hopefully) will stand the test of time — and several showers —
I considered using it for the shower floor, but not sure, – my shower pan is built using the traditional method (mortar,liner,mortar).

Is there anything bad about using silicone (not latex but 100 silicone) on shower walls/floors?

Thanks

Reply

Roger

Hi Patrick,

Are you talking about using it rather than grout? If so you should not do that. Silicone is meant to be a regular maintenance issue, it needs to be replaced every 5-7 years because it loses it’s elasticity and begins to shrink. If you use it rather than grout it will do that in all your grout lines. If you’re talking about something else you’ll need to let me know what that is.

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Patrick

Thanks Roger, yes, I was talking about using 100% silicone instead of grout.
My grout lines are 1/32 (1 mm) and…I already did it… on the walls only. So, I guess I will have to redo in 5 years…should I wait or start tearing out now? The lines are pretty deep and are completely filled. The silicone is marked as permanently flexible, I guess I was sold on that statement.
For the floor I used unsanded grout with grout booster. I was debating on the use of “fusion pro” (from HD) but their instructions were not clear as far as their use in shower and I felt a bit intimidated by epoxy grout.
Your advice is greatly appreciated.

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Roger

I honestly would remove it and use the same as you used on the floor. You can wait if you want, but you’ll end up removing it anyway as well as cleaning up any nasty stuff that decided to grow in there in the next five years.

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Patrick

Thanks Roger, I will wait until I have to redo the silicone in the change of planes to remove the whole thing. Hopefully my dog will not burst into flames.
Really appreciate your advice, and all the helpful tips.

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Monica

Hi Roger, I came across your site trying to find an answer to a current debacle. I am having my bathroom redone and using 4×12 glass tile in the shower. Problem is, the measurements were not done correctly to begin with and the shower is weirdly shaped – with a 45 degree angle by the door (right side of shower).
The tile on the left and in the middle have been set and now they’re at the last wall. They didn’t realize they couldn’t cut the glass tile at an angle, because that changes the appearance of the tile, so now it’s butting up against the tile from the middle wall – with a large gap in between. The tile installer has recommended using grout to fill in space, but it looks like an awfully big space and I’m concerned about movement and cracking – especially since it’s glass tile. Other than starting over, which is not an option, do you grout or caulk or both? And with glass tile, do you use sanded or unsanded? Any suggestions on how to move forward?

Reply

Roger

Hi Monica,

You can grout a 45, it won’t compromise the glass at all. The type of grout is dictated by the size of grout lines. While sanded grout MAY scratch glass, I’ve only seen it twice in 24 years, and both times it was cast glass (over $100 sq.ft.).

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Chris

My work partner and I do a lot of bath remodels and I would like to add to your original post.

Whenever we have a new stand up shower to build we leave grout lines for everything, (we like 1/8″ for a 12″x12″ and under) also we use 100% silicone (clear usually) in all of our corners after the grout has set. The grout sucks it up so you get some flexibility and a great bond that will last.

Clear paintable silicone is also wonderful to use at any spot where you might have a grout/paint border. It stops the grout from wicking the paint in and you can keep a nice straight line. Just some extra for you do it yourself era

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Doug Thompson

Hi Floor Elf.

Please help. We have white 4 x 4 tile in our master bath and the grout seems where floor and wall (also tiled) are cracked and crumbling in spots. I’d like to scrape away the old grout and then re-grout, but I’ve been reading that “changes of plain” should be caulked. Is this correct? I know that eventually I’ll get more cracking, but in my opinion, grout will look better than caulk, at least in my situation.

Thank you in advance for any help or advice you can provide me.

Doug Thompson

Reply

Roger

Hi Doug,

As I stated in the fairly lengthy article above where you posted your question yes, it is correct. It needs to be siliconed or caulked – grout will crack. But you already knew that.

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Sharon

We have removed grout from a honed slate shower (with granite sills on two sides, tile under these) showere was previously all grout. One can see the crack on one vertical change of plane–however clearly there were leaks where walls met the floor and or sill met the tiles). Siliconiized acrylic was used for the entire shower as a fix…and of course failed. It just gets wet and washes out, rinse repeat. I have attempted to remove most of this and the contractor will re-grout.

Naturally I am nervous about using the siliconized acrylic caulk for change of plane. The folks (spoke to two different technical specialists) at Tec tell me one should NEVER use this product where floor meets a wall. Always use silicone. Along with no grout in the joint, no hollow spots (not sure what these are?)’ go DEEP (maybe trying to make sure we ar not just covering up the grout?)’ it’s to be a “rope” around the base, needs two edges to attach to.

That leads to the issue of, really? I don’t read that often and gosh it sounds hard to apply? But clearly the siloconized acrylic is not intended for this? My tiles from floor to wall do not overlap — in other words, they meet at their edge and floor tile doesn’t go under wall tile.

Grout has been removed from floor tiles and one tile (12″) up the walls and from underneath the sills.
Thank you!

Reply

Roger

Hi Sharon,

If by ‘leaks’ you mean there was actually a leak in your shower into another part of the structure then your tile, grout or caulk has absolutely nothing at all to do with it. Siliconized acrylic should not be used at wall/floor transitions. Silicone is what you want to use. It isn’t that hard to apply, they’re going to tell you everything they can think of to cover their ass. It applies just like the caulk.

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Sharon

Roger–Thank you!

And no, by “leaks” I meant through grout joints, not an actual leak –at least not that we know of!

That helps tremendously, duh, of course it’s just a CYA.

Reply

Andy

Hi Elf ; )

Im about to grout my first tile shower and am wondering about order of things. Ive got a siliconized latex caulk and fusion pro grout (both products from custom – so colors are a match). Im gonna fill all changes of plane with the caulk first and then once thats dried – start-a-groutin. Is that order right?

Im also wondering about the spot where the grout meets the caulk. Is this a weak point or will the grout fully seal up to the section of dried caulk?

Am I over thinking this?

thx
Andy

Reply

Roger

Hi Andy,

You can do it either way, but you’ll get a better seal and bond if you do the grout first. The caulk will bond to the grout, the grout will not bond to cured caulk.

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Andy

exactly what I did – and it turned out great. Thx!

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Marilyn

Great site with great info. I have a granite kitchen counter 18 years old that looks perfect. Still shiny been though I abuse the heck out of it with cleaning products. The grout/caulk between the 4″ backsplash and counter needs replacing. Do you think a first timer is capable of doing this (me)? How difficult and do you suggest caulk? If yes, which brand is the best (I need a color)? Thanks.

Reply

Roger

Hi Marilyn,

Yes, a first timer can definitely do it. I suggest silicone. Laticrete and TEC both have numerous colors that can match your grout or granite color.

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