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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ZACK JONES

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.

Reply

Roger

Hi Zack,

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

Reply

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.
Thanks!

Reply

Roger

Hi Marc,

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

Reply

Val

How to remove e-mail address after leaving a comment

Reply

Roger

Hi Val,

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

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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.

Reply

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).

Reply

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?

Reply

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.

Reply

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

Reply

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.

Reply

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