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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Doug

Roger,

I have a question I couldn’t find the answer for. I replaced a 1970s cast iron tub and shower tile installation with a new acrylic tub and porcelain shower tile. There is now a 3/4″ gap between the tub and old floor tile (parallel to the floor) that I need to waterproof to keep the subfloor dry. I am planning to use white porcelain quarter round tiles with some combination of thinset, epoxy or sanded grout, and caulk to seal it. Do you have a recommended procedure for waterproofing this area?

Thanks for all the helpful information!

Reply

Kevin

Hello,

When it comes to applying silicone to the change of plane what do you suggest as the best way to keep the grout out before I get to applying the silicone? How do I get the grout cleanly to the edge of the change of plane without filling the gap or not applying enough grout?

Thanks

Reply

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

Reply

Roger

Hi Tina,

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

Reply

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!

Thanks,

Andrew

Reply

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?

Reply

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?

Reply

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?

Reply

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.

Reply

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?

Reply

Roger

Hi Richard,

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

Reply

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!

Reply

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.

Reply

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?

Reply

Roger

Hi Robert,

It would be best to use silicone.

Reply

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?

Reply

Roger

Hi Jeanie,

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

Reply

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.
J

Reply

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.

Reply

Larry Stringfield

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

Reply

Roger

Hi Larry,

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

Reply

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!

Reply

Roger

Hi Buffy,

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

Reply

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