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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Sandi

So NEVER completely overlap the corner tiles because If they are touching the silicone caulk will not adhere???? Hope I can get a straight corner!!
Thanks for your patience and help!!!!!!!

Reply

Steve_in_Denver

Sandi,

I believe what Roger is saying is something like diagram A in this picture:

http://i10.tinypic.com/48ppcnq.jpg

You want your first wall to be tiled far enough into the corner so the second wall tiles will cover it, but not touching the wall (you have to allow for expansion) The second wall tiles are installed so they are close to, but do not touch, the tiles on the first wall.

Again, the not touching part has more to do with allowing for expansion than the silicone not sticking (though a really small gap might be hard to force the silicone into)

Keep the spacing consistent top to bottom, and keep lippage to a minimum and you will have a nice corner to work with. A slightly wider gap hides variation better than a narrow gap – I used 1/8″.

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Sandi

I am so confused by something you wrote regarding shower corners???!!
” overlap with one (almost) butted to the other “. Question is about overlapping or spacing tile in shower corners!
1. So overlap BUT leave enough room for a grout line?
OR
2. Completely overlap a tile on top of other tile then use a silicone caulk because grout will not stick??
Just confused about how is BEST way to finish corners!!!!

Reply

Roger

Hi Sandi,

Overlap but leave a gap. I did not say butt (which would be an overlap without a gap). ALWAYS use silicone in corners, not because it will stick and grout won’t, but because changes of plane need to remain flexible.

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Linda D

Hi Roger, well my plumbers just left and said the leak is in the shower which was installed 9yrs ago. The tile man installed a new larger drain and pan and tiled the shower beautifully.. 9yrs later we have a leak in the basement under where the shower is. We removed the piece of the ceiling in basement and the wood supporting is soft & soaked. will the shower floor cave in ?Do you think it’s bigger that just the caulking or is it cracked pipe or pan? it’s strange on the outside of the shower door corner of sheetrock it seems to get wet. plumbers said there are no pipes behind that part of wall. But I can’t see how the water is splashing there. The Plumbers suggested before I start the big job taking the tile floor and shower off and everything else, I should try re-grout or caulk. After reading all you helpful remarks I am thinking caulk,. but do you think that could be the answer? So easy and cheap? Thinks like this never happen to me.. It would be great but……I’m not holding my breath.

Reply

Roger

Hi Linda,

It’s much bigger than that. Obviously your shower is not properly waterproofed or your waterproofing has been compromised. The only fix is to replace it with a properly built shower. Water WILL get behind tile and grout, neither are waterproof. Caulking over it will only slow the leak, but it will still leak. And slowing it down and putting off replacement leaves a LOT of time for mold to begin (or continue) growing inside your wall cavity which literally eats away the framing of your house.

There doesn’t have to be pipes behind a wall in a shower for water to get behind the tile. If your shower walls and floor are not properly waterproofed that water will not end up in the drain. Your plumber apparently doesn’t know that grout is not waterproof.

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Linda D

ok we have a tile man coming, if he removes the floor tile to see pan & drain if cracked could he see if the wall board is waterproof green board.?
The water on the sheetrock corner *outside* the stall maybe 4″ away from frame there is tile top, how does it only get wet there can’t figure that one .
Thank you Roger for your quick response!

Reply

Roger

Green board is not waterproof. So if that’s what is back there that is part of the problem anyway. Any type of drywall (green board included) will soak moisture like a sponge and water will travel to different parts of it behind the tile because of that. It’s like saying I’ve only put one end of the sponge in water, I don’t know how the other end became wet. That’s why your sheetrock corner is wet.

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Diana

Hi, Roger.
Just recently I read information on your website about greenboard and I have just learned that, although used in shower areas in the past, it does not conform to actual codes as it disintegrates when wet. Ten years ago, a contractor got rid of my tub and converted the space into a stall shower. He installed the pan and tiled the shower all the way up to the ceiling. Once the job was done, he unloaded some panels from his truck to make room for his tools. But … he forgot to load a large piece of the now dreaded greenboard which I saved for him in my garage. Since my husband passed away, shortly after that bath was finished, it has never been used. Now that I read all about greenboard I am in a state of panic thinking that the contractor might have used that material on my bath. My question: I am planning on remodeling the guest bath which is adjacent to the one already done. When the new contractor guts the guest bath’s walls, would he will able to look inside and tell me if green board has been used in the other bath? If not, how can I find out – removing a couple of tiles, perhaps? I don’t want the greenboard to get wet and the tiles to fall on someone using the shower that was finished ten years ago. Sorry about a long post.

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Roger

Hi Diana,

Yes, once the adjacent bathroom is gutted you’ll be able to see the back of the wall substrate through the studs, as well as any water damage or problems, should they exist.

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Kym

Good afternoon, Roger.
My husband and I are attempting a ceramic tile project together. I’m getting over my perfection issues and he’s getting over the fact that I wanted something other than a plastic shower shell. It’s been a bonding experience. Speaking of bonding, we have discovered we used too thick and dried out mortar for our wall tiles….about half wall. We took down the row that just wasn’t sticking. Everything else is stuck solid. Do we need to take it all down and start over or just start where we are with smooth thinset? Thanks so much for your advice.

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Roger

Hi Kym,

Just start again where you are, no need to take it all out.

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Dave

I installed basalt floor tiles with laticrete 253 gold mortar. I sealed the tiles with two coats of aquamix professional sealer’s choice gold prior to installation. I was not careful enough about removing stray mortar from the surface as I did the installation, and now have several spots of dried mortar that do not go away with water, sponge, and bristle brush. What would you recommend I use to try to get the mortar out of the pores of this material/

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Roger

Hi Dave,

Metal dental picks are the best thing I’ve found for detail work like that.

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Jeff Ward

Hey Roger…thus far your help has been invaluable…

Yet…another “intelligent ” question… :bonk:

The Tile Shop I purchased supplies from recommended I grout the Slate 12 x 12 walls and floor pebble mats in the shower FIRST…then seal…

Since I need to Caulk all of the “changes of plane” …corners etc…do I caulk after the sealer or before? :?:

Thanks Much :-D
Regards

Jeff

Reply

Roger

Hi Jeff,

You can do either, or both. Sealing before grout makes it much easier to clean up the grout. Either one works, though.

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katienealle

Ok, so I had “a guy” install a shower a few years ago. It’s travertine tiles on the walls, with 2 niches and a riverstone floor. He apparently wasn’t the best tile guy every and there is a wide variation of grout lines. Some are fairly small ~1/16th inch, but some sections and changes of planes are much wider (largest is about 1/2 “). He originally used unsanded Tec grout and I am currently redoing it as it was cracking, falling out and had open holes, etc. I am stuck trying to decide what to use here. Sanded on all grout lines? Just on the big ones? What about those wide corners, niches corners and changes of planes? Silicon caulk to be technically correct? Also, do you seal tile after grouting to make sure grout is sealed as well?
I am really interested in doing this right this time…I don’t want to do this again in a few years;)
Thanks!

Reply

Roger

Hi Katie,

Use sanded on all of the grout lines. Silicone at all changes of plane. Yes, seal again after grouting in order to get the grout sealed as well.

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Kirk

Roger,
I have a ceramic tile shower that is grouted at the planes. The pan is ceramic as well. The grout at the joint of the floor of the wall is coming loose. Should I repair it with more grout or use caulk? If I use caulk is it necessary to remove all of the grout before caulking? Thanks

Reply

Roger

Hi Kirk,

You need to remove all the grout and replace it with silicone.

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Steve_in_Denver

I’m planning on using caulk in my shower at changes of plane.

1. I want to use a Laticrete product to match my grout. The silicone (Latasil) is the better choice over the acrylic, yes?

2. The Latasil instructions say to use the 9118 primer. Any advice on this? (Is it necessary? Tips / tricks to install? Suggestions of where to buy a single bottle?)

3. What is the correct order to install:

Stone sealer
Epoxy grout
Primer + silicone
Shower glass

Seems like I need to grout before the glass goes in, and I thought I needed to seal the stone before I grouted, but the glass company has asked that I don’t seal the stone before they install the glass (the silicone doesn’t stick as well), which has me wondering about the silicone in the corners too. Don’t want my dog bursting into flames, you know.

Thanks

Reply

Roger

Hi Steve,

1. Yes.

2. Not really required, it simply removes all foreign substances from the space where you’ll be caulking. You can do the same with denatured alcohol and a clean towel.

3. Unless you are using a topical sealer the silicone will bond to sealed tile just fine.

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james

What about the fancy metal/PVC profiles that Schluter and other companies make for changes in plane? Like Schluter-DILEX (where do they get these names from? IKEA?) I really haven’t seen any non-marketing how-to’s or opinions about it. I like the idea of zero maintenance beyond normal cleaning. But will it look cheesy?

I’m doing my first shower with white 12×24″ wall tiles meeting the floor with a grey (basalt) 2″x4″ boarder and basketweave field. Linear Schluter drain on one end.

I love learning new things and this entire process is new to me.

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james

UPDATE… just got a quote from a supplier of profiles…. $600 for the shower and baseboard. Yikes! How long should silicone caulk last? I’m really good at caulking. Kinda thinking the profiles aren’t worth it.

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Roger

See? :D That’s why you don’t hear about it. Silicone should be replaced every 3-5 years.

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Roger

Hi James,

I love the Dilex. It looks great with the right tile. You probably don’t hear much about it because it isn’t cheap. :)

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Jay

I am tiling a show and have a pre-made base. I have waterproofed the walls per your guide (thanks!). When installing the first row of tile on the base (12″ porcelain) to they rest on the base or do they need to be raised a bit.

Reply

Roger

Hi Jay,

You need to have a 1/16″ – 1/8″ gap between the pan and tile which will get filled with silicone.

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brandon

Hey Roger! Thanks for all the great advise! Browsed thru a bunch of questions but didn’t see mine so…

1. When you do your corners in a shower stall, do you butt the corners of the tile up to each other or overlap one edge over the other? Does it matter?

2. If you can overlap the corners could you stagger the pattern side to side as you go up?

3. If You butt them how much gap do You leave? Im using 3/16 tile spacers.

Thanks Rodge!

Reply

Roger

Hi Brandon,

1. Overlap with one (almost) butted to the other. Yes, I know that wasn’t one of the options.

2. No

3. 1/16″ – 1/8″

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Chuck Liberman

Hi. My building inspection requires insulation on the exterior walls in the shower. Inspector suggested Reflectix which is plastic honeycomb sandwiched between aluminized layers. I was going to use Redguard on the concrete board walls. Won’t this be like having 2 vapor barriers which is a no no? Which would you suggest changing? Love your books.

Reply

Roger

Hi Chuck,

You can have Reflectix behind the substrate. It’s not ideal, but if it’s required, it’s required.

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Waaa Hoo

Sanded or unsanded grout for shower corners? Plan on using Tec Powergrout.

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Waaa Hoo

Doh. I meant to ask “sanded or unsanded CAULK for corners?”

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Waaa Hoo

Plus: Any super cool tricks like the bullseye pattern on ceiling tiles for tooling caulk neatly?

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Roger

Install it, spray it with denatured alcohol and run your finger down it. As long as the top of the bead is wet it won’t stick to your finger.

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Roger

Oh, sanded. :D

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Roger

Silicone.

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Waaa Hoo

Sanded silicone it will be.

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Larry Liddell

I would like your opinion on the Kerdi shower pans. I am on a concrete slab and would like to use the Kerdi shower kit.

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Roger

Hi Larry,

They’re a good product. I just don’t use them because they rarely fit the size of the showers I build.

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Ben

Hi Roger
You mention epoxy grout as acceptable to use at the change of plane. What’s your opinion on the urethane grout for the same application?

We’re using urethane grout on large format glass tiles in a shower remodel. The good folk at Bostik, who we purchased the grout through, are of the opinion silicon is the way to go at the change of plane but don’t have a product to match to the colors of their urethane grouts and suggested a color match with the tile instead. The tiles are a clear glass with a colored backing and we would like to avoid this approach if possible. A tad apprehensive about the appearance of the finished product Don’t want to have to scrape it out if it looks rubbish.

Can you shed some light on color matching caulk/silicon to glass tile and can you suggest a suitable product/brand you found satisfactory for the job? Are there brands who make a caulk that might match up to Bostik’s urethane grouts?

Any wisdom you can impart on this would be greatly appreciated.

Cheers
Ben

Reply

Roger

Hi Ben,

With large format glass I would absolutely NOT use grout at your plane changes. With clear glass and a colored backing you can go with clear silicone (which WILL hide the very back corner behind the tiles that you see now) or a color that matches the color on the back of the tiles. Clear is likely a better choice. There is not going to be any company that makes a silicone to match another manufacturers grout colors. You may be able to cross-reference your color with laticrete or color-sil silicones. If you call either one of them they’ll be able to tell you which to use.

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Renee parks

Should I use caulk in the corner joint of my green board, which is in the “dry” area of my bathroom, and the tape and thinset since it’s getting tiled? Also, can you tile over green board Ina dry area? I know it’s a no-no in showers, but what about the rest of the bathroom? And can I use a liquid membrane on the green board in this area, or do I even need to? I’ve read through a LOT of the comments, but have found conflicting information. Thanks!

Reply

Roger

Hi Renee,

No need for silicone, just tape and thinset. You can tile directly over it in dry areas. You do not need a liquid membrane.

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Dave Schmidt

Well here goes.
Have studded in. rough opening is 37 X 54. Will be tilling to ceiling. Want to tile floor.
Question one. Do I need to support the floor trusses in the basement?
Question two. Would like to get your books. I’m old (67). Like to read on the bathroom potty fixture. Want to do the job right, preparing and tiling the walls that is.
Need info in book form with pictures. Need to do the whole thing right. What books would you suggest?
Thank you for any suggestions and advise you could give. Love your text in the readings I did.
Dave

Reply

Roger

Hi Dave,

1. No, they should already have sufficient support.
2. It depends on how you plan on waterproofing the shower. If you download my free waterproofing manual it will walk you through the different methods and pros and cons of each. You can decide from there. You can find it here: Shower waterproofing manual

Reply

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