Filling Grout Lines with More Grout

by Roger

When there is a significant amount of movement on the substrate of a tiled floor or wall it may lead to grout cracking. When this happens it will leave what looks like a crack in the grout where it has come away from the tile. Unless your grout was installed very recently this is always due to movement in the tile. If your grout is new it may be caused by incorrectly mixed grout. With grout that has been doing this for a while it may lead to whole chunks of grout coming loose and leaving large voids in your grout lines.

While it may be tempting to simply mix up some more grout and fill these voids you need to know that it will not last. If you do this it will fill the grout lines just like new but over time will lead to the same problem. Grout over grout is not a permanent solution.

Why it won’t last

The first reason is that when you go over the top of grout that is already cured with new grout, there is no adhesion to the old grout. It will instead simply create a layer of grout on top of the old grout. These layers have no way of  sticking to each other. When you grout tile the grout actually sticks to the sides of the tile rather than whatever substrate is beneath it. While it will stick to the substrate at the bottom of the grout lines to an extent, it is not a permanent bond. Attempting to grout over the top of old grout is simply stacking two seperate layers of grout. It will always remain two seperate layers.

The second reason is no matter how much of the old grout you may take out to install new, if you do not fix the actual reason the grout failed in the first place, eventually the same thing will happen again. As with any problem you may encounter with a tile installation, you must figure out the initial cause and fix it to prevent repeated problems. This is an involved process which I will cover in a different article. For now I’ll stick with the solution for the grout problem.

What to do

Rather than simply filling the grout line where the grout is missing, you must remove the old grout at least 2/3 the depth of the tile so the new grout has a feasible surface to grab onto. The easiest way to do this is with a grout saw. Ideally you would remove the old grout all the way to the substrate before regrouting it, but 2/3 will be sufficient if it is difficult to remove.

You need to remove any of the old grout that seems loose or has come loose from the sides of the tile. You also need to make sure the spot where the new grout butts against the old is a 90 degree angle, or close to it. In other words from the top of the grout line straight down. You do not want a slope. Eventually a slope must be feathered to a very thin edge. That will be the first place it will fail again, any very thin layer. A 90 degree angle prevents that.

It is also better to make the transition from old grout to new in the middle of a grout line rather than at one of the corners of the tile. The grout line at the corner of the tile has six different spots it can fail, the middle of a grout line has only one. It lessens the chance of failure.

After you remove the sufficient amount of the old grout just mix some new grout and fill the lines. You must make sure you force the new grout into the grout lines very well. You want to make certain there are no voids and the lines are full.

The above method will work to temporarily fix your cracking grout. As I pointed out above, you must find the initial reason for the grout failure before a permanent fix will last. It’s difficult to say how long this fix will work, it may be two weeks, it may last a year. That depends on the severity of the problem that caused it. It also depends on the application (wall or floor) and how much use it gets. A floor in your main entryway will not last as long as a shower that is never used.

You should also take into consideration the age of the grout. If you are repairing grout that has been installed for five years, the new grout, even if it is the same brand and color, will not likely match perfectly. The best solution, of course, would be to fix the cause of the cracking and regrout the entire floor. Depending on what you’re fixing and why this method may solve your problem.

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Debra

Hi Roger!
I apologize for the typos in my previous post. I was speaking to Siri. Anyway…my husband and I thought we could raise the grout line flush with the tile by adding to the top of the grout that was put down 6 months ago. I was told epoxy will stick to epoxy, but regular ground won’t stick. What would you do? We are so unhappy with the contractor we really don’t want him back.

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Debra

Hi Roger! I was looking through the postings on this site for problems with Epoque see grout and I didn’t see anything, so here is my question… Six months ago we had ceramic tile put down on our new kitchen floor and the contractor used epoxy grout. The grout is not flush with the tile and when sweeping and mopping it is very difficult to get the grout clean. My has been and I thought we would get some more epoxy grout and add to the top of the grout to make it flush. Will a fresh epoxy coat stick to the old coat? We really don’t want the contractor back. What would you suggest?

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Pamela

Hello Roger,

I’ve been reading through your site today. I’m from Colorado also, Stanley Lake area. Go Broncos! Left the summer of ’85 and now reside in Maryland but still come back to visit friends and family.

I’ve attached a photo of a small section of kitchen backsplash, installed between 7-9 (time flies) years ago. I’ve yet to grout it. I like the way it looks and it’s holding up well (no spaghetti sauce spills from this Italian) so far. I just can’t find/decide on a color that will have the same effect/look/hue and there’ve been other jobs to tackle…aka the money pit. I’ve been told I need to grout before cleaning and resealing the granite counter tops. Not sure why? Can it be sealed and not grouted since it’s held up okay thus far? If not, what type of grout and color would you suggest for the combination natural stone (two colors) and glass mosaic…if I really must grout it?

Sincerely,
Stuck (in Maryland)

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Emily

Hi! Thanks so much for all this info. My husband and I decided to tile our powder room in the last few weeks (yes you read weeks correctly now add 3 kids under 5 that primarily use that powder room- it’s been a long few weeks hehe). We did a wonderful job the tile on the walls is beautiful, the paints perfect and as we are about to put the toilet back (hallelujah) we notice the teeniest bit of cracking between several tiles on the floor. I could have cried, I may have cried. It has not been 28 days should we add more grout, get the old grout out and regrout (as i know you said is a temporary fix), give up and acknowledge that though we are very handy those tiny hexagon tiles won this game?

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Emily Mortland

Hi! Thanks so much for all this info. My husband and I decided to tile our powder room in the last few weeks (yes you read weeks correctly now add 3 kids under 5 that primarily use that powder room- it’s been a long few weeks hehe). We did a wonderful job the tile on the walls is beautiful, the paints perfect and as we are about to put the toilet back (hallelujah) we notice the teeniest bit of cracking between several tiles on the floor. I could have cried, I may have cried. It has not been 28 days should we add more grout, get the old grout out and regrout (as i know you said is a temporary fix), give up and acknowledge that though we are very handy those tiny hexagon tiles won this game?

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Sandy

Hi, Roger…we have a very large 7 yr old shower with river rock on the walls and a tile floor. There are hairline cracks along the wall/floor joint that appear to be the culprit in leaks through the ceiling of the level below (dining room!). Also could be leaking grout lines in the tile floor. Plumber recommended cleaning and resealing, which I can do, but how do I patch those joint cracks? Hate to use silicone as is too shiny! Thank you…

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Beth

Hi Roger,
We just had a bathroom redone. The shower walls were done with marble. It’s been about 2 weeks. We just went to seal it ourselves and noticed crackes in the grout! Can we add grout since it’s been 2 weeks, or will we have to remove the original grout first?

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Beth

See pic

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Tom

I put grout on a place stone shower floor today. It’s sands grout with some pretty big grout gaps. I cleaned to much grout from them and I also see my thin set poking through in some places.
Can I just clean those spots out and regrout the whole floor?

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Roger

Hi Tom,

Normally yes.

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Tom

Thanks for the reply. I cleaned up those spots where the thin set came through, and re grouted tonight. I didn’t clean is so much. It’s got a glaze over it right now. I’m gonna let it dry, and scrub it tomorrow.

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Richie

Hi Roger, we just had tile installed in our shower amd after the grout dried we noticed what seemed to be small holes, guessing it was cause by air bubbles? What should we do?

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Heggy Gonzalez

Hi roger my tile guy just grouted today and there are a bunch of holes is the grout. Reading through your posts it sounds like I can just go over it again since it has only been a day?

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Heggy Gonzalez

Here Are some pictures plus I thought it would be a lot darker can I stain it or just go over with a darker grout?

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Roger

Going over it with a darker grout will not work, you’ll see both colors. You can stain it if you want, but you’ll need to wait at least 28 days for a full cure.

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Roger

Hi Heggy,

Yes, you can. But I’d make him do it, you know, since you’re paying him to do it correctly and everything… :D

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Kevin Stock

Hi Roger. Four days ago, my contractor grouted my new floors, but washed away too much of the grout. Is it too late to just add another layer to make it more flush with the tile? Btw, the day after it was done, I asked the contractor if it can be done, and he said no, that the grout was already rock hard. Thank you.

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Roger

Hi Kevin,

Anytime up to 28 days when the cement crystals are fully hydrated.

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Kevin Stock

Wow! Thanks Roger. I thought the window for adding more sanded grout was only 2-3 days. Shall I tell my contractor he has just under a month to add another coat of grout? That would be much preferable than trying to take it all out. The lines are 1/16″ so I was told it would be next to impossible to remove the grout without damaging the glazed porcelain tile. Thanks again!

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Kevin Stock

Oh ya, yes I said he used sanded grout on 1/16″ grooves. Even the bag says it’s for 1/8″ or wider. It feels not only too deep (washed out) but also very coarse. The grooves are a complete dust trap. I used black grout, but it looks like I used white because of the dust! Should he have used non-sanded grout or is he ok to choose whatever he’s comfortable with? On the day of grouting, I suggested non-sanded grout and he said no.

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Roger

I always use sanded grout on 1/8″ and 1/16″ grout lines. But I know how to do it correctly, he doesn’t seem to.

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Kevin Stock

Here are a couple of photos. I repeatedly asked for high grout lines in order to achieve a unified, almost poured concrete look. The tiles are beautiful and they were laid well, but the grouting was clearly an afterthought. The contractor is willing to do another coat, but he says it’ll probably chip off. He asked me to research what coating I’d like to put on top. I was thinking maybe epoxy grout, since it’s like plastic and tends not to chip. What would you do if you were me?

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Kevin Stock

This one shows the black grout looking white.

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Roger

He used WAY too much water when cleaning the grout.

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Roger

You should tell your contractor to get in there now and fix his screw up. :D

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Kevin Stock

Thanks so much Roger! The tiler recently discussed with the contractor the possibility putting on one more layer of grout, but this time using non-sanded. He said he can’t guarantee it will not chip off, though. What I would like them to do is fix the situation in a way that will not void my warranty. I don’t care how they do it as long as they’re willing to stand by their work. If a second layer of something chips off, I need them to come back in and try something else. Their position is that it’s not an option to remove the grout and start again because that process will chip the tiles. He said he’s not willing to take that chance. Do you think it’s possible to remove the grout so they can start over? Or do you think they should just add another layer of unsanded? How about a layer of epoxy grout? I heard it’s super strong and smooth. They just think I’m being fussy and unrealistic in my expectations. But I don’t think so. I’ve made it very crystal clear on multiple occasions prior to the grouting that I wanted a seamless, unified look to the floor with high grout lines. I don’t like it that even when I sweep the floors, my black grout lines look white. I don’t want to have to mop the floors or vacuum the grout lines in order to make the lines look black. Your help in this has been invaluable. Thanks again!

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Roger

The unsanded may last, depending on the cause of the problem. If it’s simply low grout lines it should be fine, if there’s movement in the substrate it won’t last. Unsanded is a better option than epoxy in this situation. The epoxy will bond tenaciously to the sides of the tile, not so much to the existing grout. Being that there is currently more grout area than tile area to bond to the epoxy will likely not work well.

Grout can absolutely be removed without chipping the tiles if it’s done correctly by someone who knows how. If he said that – he apparently doesn’t have anyone who knows how. If they’re willing to stand behind the unsanded option I would let them give that a go.

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Kevin Stock

Thanks again, Roger. You’ve been invaluable in this process. I’ve attached a photo I sent to the contractor and sub-contractor that indicates the kind of seamless effect I was looking for. I was surprised to recently notice that it is, in fact, impossible to clean my grout lines enough to make them look black. They always look white. It seems that not only was too much grout washed off, but the dark colour was washed out as well. Thanks again!

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Michelle

Did your contractor use purified water to prepare the grout? If not, he should have done that, tap water contains little to big amount of minerals, and with the pass of time, all that minerals become visible turning even a black grout white… he also needs to use a non-sanded grout, it’s the one everyone should use in bathrooms because it prevents from getting fungs.

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Jeanne-Marie Lovell

I just grouted using polymer-enhanced sanded grout, but the tiling job we laid is kind of uneven. It was really hard to get the grout as deep as I wanted it. But you say I can lay more on top within 28 days?! It’s been less than 24 hours. Should I go for adding more? My only previous experience is making small mosaics.

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Roger

Hi Jeanne,

Sometimes it works, sometimes it doesn’t. It depends on a lot of factors. Give it a shot, worse case you’ll need to dig it out and do it again anyway.

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Jamie

I just did one layer of grey grout to my backsplash with the new trend of grey color….I hate it.

Can I just go over the grey grout with white? Or do I have to grout saw it? Will this ruin my new subway tile??

Thanks!

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Roger

Hi Jamie,

You can, but it won’t be white, the gray will show through in areas and it will likely flake off over time. You need to remove the gray. No, it won’t ruin your subway tile.

Stop following trends. :D

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Christina

Hi,
I need some help. My husband and I just paid a lot of money to have a flooring company lay wood plank tile through out our downstairs (1200 sq ft). Needless to say they did an awful job and I’ve basically fired them. The tile isn’t completely level at the grout lines, there are holes in the grout where there were probably bubbles while they were grouting, and the grout lines aren’t the same sizes – plus some of the grout is sitting on top of our tile. In some areas I can still see the side of the tile itself and to make it worse I ordered brown grout to match the tiles and they put down gray. Now its on us to fix this mess.

Besides tearing it up and redoing the tile – do I need to drill out all the current grout lines before i regrout the tile? The floors have only been down for about 2 1/2 weeks so its still new. Any advice you have is greatly appreciated.

Thank you

Christina

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Roger

Hi Christina,

If it is over about three days old you should scrape out the existing grout before filling it with more grout. Grout bonds to the sides of the tile, not the substrate beneath it, which means it has trouble bonding to existing grout and remaining stable. You can try to grout over it, but I’m afraid it will begin to sheer off after a couple of weeks.

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Andrea

Hi Roger,

Our 1953 casita was remodeled with 12 x 24″ tiles through the 700 sq ft. The LR is on cement, but the bedroom was on a subfloor (after we ripped off the carpet and then the old, laminate, original tiles). The tile was installed, looked great, but nobody stayed there as it took awhile to pick out new furniture.

After a few months, someone stayed there for two weeks and two of the tiles had cracked grout around them. That is when I asked the contractor to come over and they said that there is movement. When you stand shoulder width apart and shift your weight you can feel the floor move. We have cracked grout on a few tiles. The tile guy said he’d re-grout and if it happened again, he’d come back. As you predicted it has broken down again and looks like crap…and the tile guy is ignoring my calls.

It sounds like you’re saying that I have to rip it up and retile! That’s the only option? Ugh! This tile wasn’t cheap. Maybe I’ll have to carpet the whole bedroom to cover up the crappy tile job instead. Hugely disappointed! How about a grout that has rubber in it? A malleable grout? Something else besides “rip it up”?

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Roger

Hi Andrea,

Sorry, no such animal. Unfortunately that is the only long-term solution.

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Josh

I grouted a river rock shower floor 2 1/2 weeks ago. I haven’t done anything with it since as I have been waiting for the shower door to arrive. I have noticed that there are a couple of areas where I wiped too much grout out, causing low spots. Is it too late to just add additional grout over the top? If not, how do you suggest doing it? Just the low spot or the low spot and surrounding area for it to blend better?

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Roger

Hi Josh,

You should be able to go over it just fine. Do the low spot and a portion of the surrounding area to blend it.

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