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CLM 09-27-2010 10:27 AM

Repairing missing grout in shower stall

My home is 15-20 years old, and large sections of grout are missing between the tiles of my shower stall. The tiles are tight set, and I plan to scrape the grout (but not remove it down to the backer board) and regrout with a non-sanded grout.

I read somewhere to add Berylex to the grout mixture to enhance waterproofing and bonding with the old grout. I can't find it at Home Depot or Lowes. Is there something similar under a different name?

There's also a deep gap (1/4" wide) between the bottom row of tiles and the fiberglass shower pan. This appears to have been filled with a combination of grout and caulk, but it's all loose and coming out.

I plan to remove all of it. Should I replace it with sanded grout, and caulk over it? Or try to squirt caulk alone into the hole until it (hopefully) fills?

Lastly, the vertical corner seam (tile to tile) is missing a lot of grout. Should this be all caulk instead because it's a change in plane? Or grout with caulk over top?

Thanks for any help. I haven't used the shower in a year, so any water or mildew should have dried by now.


CLM 09-27-2010 04:00 PM


I tried to scrape the old grout to remove any loose bits and prepare it for a new layer of grout, but I'm having trouble. It looks like someone tried to fill in some of the gaps between the tiles (where the grout was missing) with caulk. So in any given area, I have about 1/3 missing grout, 1/3 "good" grout, and 1/3 caulk over grout or caulk over a gap.

I can't fit a proper grout saw between the tiles - only a razor blade will fit, and that cuts the caulk but doesn't remove it. I tried caulk remover (liquid and gel), but there are so many gaps that I'm worried about getting the wall behind the tile wet.

I'd like to use the shower again, but we've already had it leak into the kitchen underneath (years ago) and don't want to repeat the experience.

oh'mike 09-27-2010 06:17 PM

Can you post a picture--what you are describing sounds a lot like a failure of the backing board--

With the smaller tiles that are set close like that--a utility knife is about all that works---

No idea what you can do about the caulk in the grout lines--Sounds like a nightmare.--Mike--

JazMan 09-27-2010 09:15 PM

The grout cracked because there is movement, not too much of a problem at changes of plane but on a flat wall, that's real bad.

The leak you mentioned is not normal even with missing grout. Neither tile nor grout is waterproof. Waterproofing should be done before the tiles are installed. Sounds like you have no waterproofing at all.

A proper shower will not leak even if you removed at the tiles. Pics would be nice.


Bud Cline 09-27-2010 10:06 PM

Bet the tile is on drywall!:)
Bet the drywall has deteriorated!:)
Bet the walls are history!:)

CLM 09-28-2010 05:01 PM

3 Attachment(s)
Okay, I hear what you're saying about how tile and grout isn't what makes a shower waterproof, and that my shower shouldn't have leaked into the kitchen.

I've lived in the house for 10 years. It didn't leak until year 5 (or so). I had someone come in to "fix" it, and I'm assuming he's the one who caulked over all the iffy places. Everything was fine for 4 years (until last year) when I started noticing more holes in the grout. I have no idea how or when it happened - I'm not very observant. I got nervous, and stopped using that shower. I pulled out all the gross and slimy caulk around the bottom of the shower, leaving the long gap in the third picture.

I'd like to use the shower again, and thought scraping out the old grout and regrouting was the answer. Isn't it?

Bud Cline 09-28-2010 05:18 PM


I pulled out all the gross and slimy caulk around the bottom of the shower,
If the caulk was have water/moisture in the walls.:)

Pop a tile or two at the bottom and see what's there, if anything.:)

CLM 09-28-2010 06:37 PM


Originally Posted by Bud Cline (Post 508494)
If the caulk was have water/moisture in the walls.:)

That was a year ago. Wouldn't it be dry by now, and as long as new water doesn't get in there everything is fine?


Originally Posted by Bud Cline (Post 508494)
Pop a tile or two at the bottom and see what's there, if anything.:)

I can pop keys off my keyboard, but I suspect if I tried to pop a tile off I'd be creating a new problem! Not to mention trying to get it back on again.

Bud Cline 09-28-2010 08:57 PM


That was a year ago. Wouldn't it be dry by now, and as long as new water doesn't get in there everything is fine?
OK...a year ago there was moisture in the wall...probably would be dry by now.


That was a year ago. Wouldn't it be dry by now, and as long as new water doesn't get in there everything is fine?
So...what has really changed?:)

Let's review!
Jaz said the cracking grout was due to movement.
He is correct.
You said you thought re-grouting was the answer.
It's not.

One more time...
Tile and grout does not make a waterproof shower.
Re-grouting won't make the shower waterproof.
The slimy caulk (ayear ago) is a sign that water was in the wall (a year ago).
Movement is a sign that water was in the wall (a year ago).
A good guess is that the wallboard behind the tile has deteriorated from the moisture causing the wall to flex.
Flex is movement and will cause grout to crack.
Re-grouting and re-caulking will not now make the walls water proof!!!!! And will not automatically repair the damage to the interior walls.

Oh wait!!! Now we are beginning to repeat everything.:whistling2:

My guess (and it's only a guess) is that the walls have served their useful life and it's all over now.:) This "guess" is compliments of a tile guy with 34 years experience of building and re-building showers, a qualified inspector, and an experienced litigation witness. But hey-What Do I Know?:)

CLM 09-29-2010 11:03 AM

1 Attachment(s)
I hear you. The tile is probably on drywall, the drywall is gone, the tiles are shifting, and that's what is causing the grout to crack (which was my initial concern.)

Only one way to be certain!

I "popped" a tile off in the bottom corner, in the most suspicious place. Under it, I see several layers:

Furthest back appears to be continuous with the fiberglass shower pan, and disappears under the wall layers.

Next is a layer of something about 1/4" thick that appears to contain some sort of mesh. It ends (or begins) about a finger width above the curve of the shower pan. It's light brown, but doesn't appear to be damaged to my untrained eye.

About a finger width above (and on top of) the mesh layer is something that looks like cement. It's grey, and doesn't appear stained or damage either.

It might not be enough to go on, but is there any evidence that my shower was built incorrectly, as you suspect? If it is incorrect, I'm curious why the kludge fix of re-caulking any gaps appeared to fix the leak for at least 4 years. It hasn't leaked since, anyway.

If the walls are fine... how do I get this tile back on??

Bud Cline 10-03-2010 03:28 PM

Tile was installed with organic tile adhesive (mastic). That's a no-no. Mastic will get wet, re-imulsify, allow movement, trash a shower wall.

Have no idea what the substrate is.:)

CLM 10-03-2010 04:24 PM

Well, the substrate clearly isn't drywall (as previously suggested) or green board. Nothing is rotting, so I'm going with cement backer board - which from my reading would be the correct material to use. So no problem there.

I don't know how to tell visually if mastic or thinset was used to place the tile, but clearly you do. Thanks.

So, it looks like the reason why my grout cracked can be traced to two things:

1 - mastic isn't the best choice for (wet) shower walls because it can allow the tiles to shift and thus the grout to crack.

2 - the grout was poorly applied, and allowed to "skim" over between many of the tightly set tiles rather than being packed fully in. (That's an observable fact.) It may also have been pre-mixed grout or any of a number of other things that cause grout to crumble and wear poorly.

I still have to decide how I want to deal with this, but at least I now know my walls are NOT deteriorated/history, and that rot is not what cause my grout to crack. (I'll replace the tiles I removed with thinset, btw.)

It's been educational, to say the least. Thanks for the comments.

Bud Cline 10-03-2010 05:09 PM

One more thing to consider...

It's hard to tell from the single photo but if "sanded" grout was used - this would account for the lack of grout in the small joints of the tiles. Those particular tiles require unsanded grout so that the grout can get deep into the joints.

From the photo it appears sanded grout could have been used, can't tell.:)

To now use thinset to replace the tiles will likely result in those tiles being proud of the others.: It's a no-win situation.:)

DangerMouse 10-03-2010 05:28 PM

Personally, I'd rip the whole mess out and use solid plastic sealed with clear silicone that never leaks.
Tiles belong on floors, not shower walls..... LOL
Feel free to disagree, but I'd never tile a shower in my home.
It's just not worth the grief nor work.
btw... a guy I know used silicone caulk on his tiles. They still don't leak any more, years later.

Just my 2....


JazMan 10-03-2010 10:08 PM


There's lots of people out there that think the same way as you. The reason is their shower was not built the right way. There are many reasons why that happened, but it almost always comes down to $$$. Everyone wants it done cheaper and there's little or no regulation on how it's done.

Nothing works right if not built right in the first place. With showers, some installers think they can get away with shoddy work because no one will know it's done wrong until years later...usually. Then again you have DIY's and handymen doing some of the work too.

There are many nice plastic shower units made, but the nicer ones must be placed inside the room before the walls are erected cuz they're to large. The cheaper ones are well, cheap looking and flimsy.

When selling, ever see anyone boasting this house has "plastic features"? Ceramic or hardwood features yes, I've never seen plastic mentioned.


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