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.
Hi Roger,
I grouted granite tile yesterday afternoon (Sat. 4 pm.) with epoxy grout. I started to use Spectra lock the weekend before but with 32nd spacing between tiles it was to hard to get in the joints so I stopped right away, Cleaned out the couple joints I did and waited till this weekend. I used CEG lite (Unsanded and more liquidly). Out of approx. 60 square feet I have two different areas about 6 inches long that has some pin holes and alittle deeper than the rest, I think I must have washed to hard as the grout was just starting to get harder to work with and wiped deeper out of the joints there. It is two areas 6 1/2 inches long at 24 hrs old.
Can I regrout over these two spots or do I have to cut it cut and redo it.
Hey Steven,
With CEG lite you can go back over is three months later if you want to. You don’t have to scrape anything out – it will bond to itself with a chemical process which differs from cement. Just go right over what you have.
Hi Roger-
I have been using a bleach pen on the grout in our shower (tile walls). The home is about 15 years old and I have been removing mold with the bleach pen probably for the last 3-4 years. I noticed the grout is now missing in 2 spots. Do you think the bleach pen “ate” the grout away?
How do I go about fixing this issue? From what I’m reading, I can’t just regrout the two spots where it is missing. Is that correct?
Andrea
Hi Andrea,
It may very well be your bleach pen. Bleach does not remove mold, bleach turns mold white. The only effective way to kill mold is to completely dry out the area. If you do have mold it is a sign that your shower, in some form or manner, is not properly channeling water into the drain.
Grout sticks to the sides of the tile – not the substrate. You can regrout those two spots but you’ll need to scrape out what is currently there to at least 2/3 the depth of the tile – then grout. Do you have weep holes in your shower?
Hi Roger,
I am trying to refinish the grout between the mosaic floor tiles in our basement bathroom. It’s a 60 year old house & somewhere along the line the original grout was covered with an unknown (by me) substance. It has a wet chalk-like consistency and can be scraped up more easily than regular grout. I can’t get it clean with any of the hundreds of cleaners & techniques I’ve tried & it won’t absorb grout paint/stain so I need to get rid of it. It’s just not rational to scrape all the grout lines between those little tiles. Do you have any idea what it is and if there’s anything I can use to dissolve it?
Thank you!
-Amelia
Hi Amelia,
I have no idea at all what it it – how would I?
Is it white? Is your tile on concrete? If the answer to both is yes it may be efflorescence. If that’s the case then it can be cleaned off with sulfamic acid, or sanded off with a drywall sponge. The problem with that is the efflorescence is likely deriving from the concrete beneath the tile itself and leeching up through the grout.
But I don’t know, I can’t see it from here.
That is just a pure shot in the dark.
Thanks or your response Roger. Yes, my tile is on concrete. The overly is an off-white/cream color. It’s definitely a separate layer over the grout because I can eventually scrape it away. I’d throw a pic of it on here if I knew how. I know you can’t see it, I just thought you might know what kind of overlays are used when refinishing grout.
Thanks again,
Amelia
You can upload a photo here. And I was just being a smart-ass – I do that.
I uploaded the pics of the grout covering even though I ended up ripping out the tile. Now I have a NEW problem. There is the adhesive mortar left behind on the cement and I can’t get it off. I’ll be trying my 3rd adhesive remover tomorrow (something with Methylene Chloride) but I’m thinking that maybe it’s not an adhesive…? I don’t think it’s thin set but if it was then that would explain the difficulty I’m having. I uploaded some pics to get your expert opinion. Again. :-)
That looks like petroleum-based mastic to me – from the 60’s. Is the floor that old? If it is a mild sulfamic acid mix should take it off.
The house was built in 54, and I’m sure it’s nearly that old. The 3rd time was the charm. I used Zinsser Adhesive Remover which has Methylene Chloride and not 15 minutes later it was as soft as putty. Thank the Lord! Now I have it all cleaned off and it’s apparent that the floor had been patched over or dug up and re-patched which is the cause for so much unevenness. I’ll be prepping it with a seal and then using a self-leveler. Wish me luck!
Hi, my elderly neighbour has some sand cement grout missing from his outdoor tiles. They are about 12 years old. The grout lines are around half inch wide.Would you just grind out the left over grout wher its missing and try to match the old grout just as a temp fix,so that his tiles dont start falling off.
Cheers Craig
Hi Craig,
The integrity of the grout does not affect the durability of the tile installation. If the tile begins falling off where the grout is disappearing the problem is much larger than simply grout. The tile should still be bonded well to the substrate.
Yes, you can remove the grout where it is loose and install new stuff. It will likely be difficult to match, but it should stay in place just fine.
Hi Roger,
Thanks for the quick reply. The grout he used on the grout lines for the wall tile was TEC unsanded wall grout. No he did not take old grout out on the wall grout lines. He just put new grout over old grout. When I said it is running down the walls while showering, it is not doing this in a liquid form but in a powdery clumpy form. The shower was leaking due to grout was cracked and missing in all plane areas ie: around the floor perimeter and vertical corners where walls meet. The grout on some of the floor and on the footer shelf that you step over when getting into the shower started getting a swelled discolored look to it in some spots and then started popping off. He removed all tile effected tiles / grout and rebuilt the footer where the wood had routed, wrapped it with rubber and put new cement board in those areas. I think he did a good job with the rebuild but I just think that instead of regrouting all the vertical corners and perimeter of the shower floor he should have used the silicone caulk. I wish I would have read your blog first. I guess I should go ahead and dig out the grout in those areas and silicone caulk them.
Thanks,
Lori
Grout bonds to the side of the tile – not the substrate (or old grout) beneath it. That’s why it’s flaking out. To properly regrout the old stuff needs to be removed to at least 2/3 the depth of the tile so the new grout can bond to it.
The curb may be waterproof now but is there a leak or is the waterproofing compromised somewhere else? Do you know? When I say it should be waterproofed beneath your tile I mean exactly that – you should be able to take a shower in it without tile installed and it will be completely waterproof. You keep stating that it leaked due to compromised grout and caulk – it’s the other way around. The grout (not in corners – in between the tiles on the same plane) cracked because something beneath it is moving more than it should. It did not leak because of the cracking – it cracked because of the leaking.
I really hope it’s waterproof now – just be sure to watch for any cracking at all.
Hi Roger–I too appreciate all your advice. Let me get this straight. From what I have read in all your responses all around the the floor of my tiled shower where the walls meet the floor the grout should be removed and silicone caulk should be added. Also in all vertical corners in the shower the grout should also be removed and replaced with silicone caulk. This makes sense to me but unfortunately I just paid my brother in law who is a handy man to fix a leak in my shower and re-grout. He did remove the grout in the vertical corners prior to re-grouting but it sounds like he should have replaced it with silicone caulk (No Grout). Also he re-grouted the grout lines on the wall tiles but now while showering the grout he added runs down the walls. I’m afraid it is just a matter of time before the shower will be leaking again. Shall I go ahead and remove the grout in those areas and re-place with silcone caulk?
Thanks
Lori
Hi Lori,
Any change of plane needs to be siliconed or caulked. The walls and floor will move in different directions, silicone can compensate for that – grout will crack.
Did he remove all the grout before regrouting the wall tiles? What did he grout it with? Grout (cementitious) does not ‘run down the wall’, it’s cement.
Most importantly – if your shower is leaking it has nothing at all to do with the grout or even silicone or grout in the corners. It is indicative of a shower which is not properly waterproofed. Anything you do to the tile at this point may slow it for a while, or it may just direct the water from the leak into the wall cavity or somewhere else you cannot see the damage. You NEED to figure out why and where it is leaking and address that problem – grout and silicone are not the problem.
Hello. I live in an old building and am having a problem with the old grout in my bathroom. the tiles are in good shape, but the grout is cracking, more imprtantly the area around the perimeter is moldy. I bleached the area and now am wondering what to do? Do I remove old grout and regrout or do i use silicone and seal all around my shower ? thank you, for this lovely website!
Hi Michelle,
If it is just the grout in the corners and changes of plane that is cracking then it’s just because it should be silicone. You should remove the grout in all changes of plane (corners, etc.) and replace it with silicone. The entire perimeter should be silicone rather than grout.
Hi Roger,
I had my bathroom floor tiled 3 years ago, and now the grout is cracking and coming off in chunks. I had someone regrout the floor bur it cracked again within a week. Not sure what the problem is or what to do. Thinking about regrouting the floor myself. The tile was put on backer board. I am not sure what the subfloor was like before the baker board and tile were put on it. Any advice on the matter?
Jim
Hi Jim,
Cracking grout, especially repeatedly cracking grout, is indicative of movement in the subfloor. It would be my guess that there is no thinset between your backerboard and subfloor. Your backer is not fully supported and any hollow, unsupported areas, no matter how small, gets walked on and there is continuous movement – this leads to cracked grout.
Do you have a heater vent in the floor you can remove and see if there is any thinset beneath the backer? If not, the only way you’ll keep it from cracking again is to replace the backer with thinset beneath it, and replace the tile. It’s simply installed incorrectly.
If there is thinset beneath your backer it could be either a structural issue (your floor was not built up enough to support a tile installation without excess movement) or improper coverage of your tile to the backer – do any of the tiles sound hollow?
Dear Roger,
We just remodeled our master bathroom about 1 month ago and we live in a high-rise . The contractor did a good enough job, but there’s one thing that doesn’t seem right: The grout is cracking in the shower where the tiled walls meet the terrazzo based shower floor. It is in two corners. After taking a shower the grout is brittle, soft ,and easy to scratch off. The other areas with grout that get wet after a shower are not soft and I can’t scratch anything off. I was told it is because of the walls moving. But why is the grout soft and brittle in the corners? Also, do I need to dry the shower after taking a shower every day or can I let it dry naturally and clean it 1 x week? Thanks.
Hi J,
The reason it’s cracking is because any change of plane (corners, etc.) need to be filled with flexible sealant like silicone rather than grout. Walls will move. Walls on different planes will move in different directions. Silicone can compensate for that – grout can not. It is brittle because of continued movement grinding away at it – it is likely not attached to much beneath the surface. Remove the grout and fill the corners with silicone or caulk.
It is always best to dry or squeegee the shower after every use – but not required.
We recently (a week ago) had our bathroom floor and shower area tiled and I noticed today that some of the grout is cracking. My question is do I need to scrape out all of the grout from the floor or just the areas that are cracking? Will it adhere to beside areas we don’t scrape out? They used sanded polymer grout and the the lines are almost 3/8 of an inch. Does that sound ok? Thanks!
Hi Crystal,
The first thing to do is figure out why your grout cracked. If you don’t do that, and solve the problem, it’s likely to just keep grouting. You can scrape out the grout to 2/3 the depth of the tile and replace it. The grout bonds to the sides of the tile rather than the substrate, so as long as you have enough removed it will adhere just fine. It will not adhere to areas you do not scrape out.
And a 3/8″ grout line is absolutely HUGE! Not that it makes much difference, but that’s big.
Hi, I recently bought a house with majority of the floor in what I call Flintstone tile with irregular edges. I don’t know if it was done purposefully, but the grout lines are extremely wide and deep (more like grout troughs), and catch everything. If I had the money I’d rip the whole floor out and put new tile in, but I don’t. I was hoping to level the floor out by regrouting but what I’m reading is I’ll have to take the old grout out first, is that correct?
Hi Jon,
You need to remove grout to at least 2/3 the depth of the tile. Grout bonds to the sides of the tile, not the substrate. If you don’t give it something to bond to, well, it won’t bond to anything.
Hi –
we put small glass tile backsplash up last night. I believe out grout was not thick enough and now we have a lot of small holes in our grout. Can we just go over it again with grout? Or what should we do?
thank you for your time.
Hi Amy,
If you used non-sanded grout then yes, go back over it to fill those areas in. Today.
my wife is wanting tile in the laundry room. I was wondering since the washing machine sometimes vibrates the floor in the spine cycle will that cause the grout to crack. The vibration is very noticeable with large loads and when it gets off balance.
Hey Brad,
As long as your floor is properly constructed and the tile installed correctly it won’t affect it at all. Mine spins like an industrial paint mixer.
Hi Roger,
My boyfriend installed glass tile to our kitchen walls as a backsplash. First time he’s ever done it, so at first it looked great until we grouted. Some of the mastic he had used to apply the tiles to the wall came through and now its still showing after we grouted. Most of the grout looks great, but there are some areas that you can see the white mastic over the sand grout color we used. Is there anyway to fix this or remove the mastic without messing up or starting over?
thanks!
Hi Tabitha,
A grout saw and razor knife will remove the grout and mastic in those areas. You can then just regrout them.
Here is my problem. Our upstairs shower was leaking, only once that we saw, in the air vent that was directly below it. We have a handy man that we use often. He said instead of replacing the shower pan, we should try to regrout it, because the seams in the flooring had cracks in it especially where the wall and floor met. The shower is 8 years old. He regrouted it, and I’m pretty sure he didnt take out any of the old grout. The floor grout was lower than it should have been, much lower than the tiles, so he made them almost flush. It looks great, but I’m worried after reading these Q&A that the new grout wont stick. Should I be?!!
Hi Jan,
What you need to be worried about is not the grout – it’s the leak. Your grout has absolutely nothing at all to do with your shower leaking – nothing. A properly constructed shower can be used without tile in it, let alone grout. The new grout may slow the flow of water into wherever the leak is deriving, but it will not stop it.
It is doubtful, unless he used epoxy grout, that the new grout will last long-term. Can’t say how long it will, just that it likely won’t. Tile and grout are not waterproof
If I don’t care about the perfect look, what is the harm of leaving small cracks in a freshly grouted tile floor? I just did the grouting yesterday and woke to find a few small cracks at the corners today. Should I take the time to do it over, will it create more problems down the road if I don’t? It’s in a sun/mud room so perfection isn’t a must. Plus, the stairs move slightly and can’t easily be fixed, old house. So that grout line will continue to crack.
Thanks for your help
Hi Michael,
No harm at all.
Provided your floor stays clean and dry and mold spores don’t get into those micro-cracks (they will) and the room never, ever sees any significant humidity at all (it will) and the floor is cleaned and thoroughly dried every day (I don’t know – that’s up to you) – no harm at all.
Thanks Roger. Will this grout stain last a long time or will it wash off after prolong washing of the floor. How long after the grout stain goes on should the sealant be applied?
Thanks.
If it’s a dye colorant you can seal it after 72 hours. If it’s a topical colorant (like an epoxy paint – sort-of) it doesn’t need to be sealed.
Roger: Thanks for you reply to my question regarding the irregularity in the grout colour. The contractor suggest using a grout stain to fix the problem. Is this a good route to take.
Thanks
Hey Daisy,
It’s one option. Most of them work just fine. Short of removing and regrouting it’s about the only option available.
Thanks Roger
You made my day, not having to scrape the grout out is music to my ears. Makes the high price of the grout worth it.
You said I can add grout the next morning and it will bond. I didn’t read your response until today, it’s been 48 hours since I botched the job. Can I still simply grout over the low spots or is there a point you would say scrape it out?
According to TEC you can do it essentially any time you want. So you can still do it now.
I successfully regrouted to fill all the low spots which was most of the floor. It looks pretty good, although I think the tile color lost it’s definition. I haven’t picked up the haze remover you suggested, but I will.
Even with all your tootering, the second time was just as hard as the first time grouting, the only diference is I expected the trouble. I won’t be using the TEC Invision ever again.
Thanks for getting me through the job, I’m glad it’s behind me, now I can move on to things that are fun like putting the appliances in etc.
I just had a new porcelain tile laid in my kitchen. I’ve had the tile man back because some tiles were raised some not (an up and down effect). I also told him there didn’t appear to be enough tile because 99% of the tiles are not flush with the grout. He only fixed the up and down tiles but I have a large floor and he said to replace all the grout would be a huge job. Now I have dirt traps because the grout is not flush with the tile. In reading some of the other people’s experiences I can’t add grout to what I have. I haven’t put the sealant on yet because it’s not been 72 hours. Is there an easy fix here? Where there’s no sealant and I do still have tile for grout to adhere to, can I grout on top of the newly laid grout?
Hi Viola,
No, the new grout won’t stick. It will initially, but in about three or four months (or less) it will begin to flake off. The easy fix is to call the tile contractor back and tell him to do his job correctly or pay to have someone else do it correctly. If you paid to have it done it should be done properly – that’s the bottom line. The grout needs to be removed and the floor regrouted properly.
I’m pretty disgusted with myself right now. I thought grouting was going to be easy, heres what happened. I bought 1/2 gal. of the already mixed grout in a 1/2 gallon bucket made by TEC. Applying the grout with a float started OK but removing and cleaning the tile as I progressed is where I had trouble. The grout didn’t wipe off with a damp sponge like I expected. I turned creamy and smeared all over the tile. At first I thought this was normal and thought I could clean it off later. As I got to the end of the job (approx.75 sq. feet) I realized the grout left on the tile is setting up quick and not wiping off easily. I began to panic and pretty much aborted the grout job and went into “save the tile mode”. The directions on the bucket said not to use too much water while cleaning because it may lead to the grout cracking later. I found I didn’t have a choice. I soaked the tile pretty good trying to make the grout wipe off easier and spent the next two hours scrubbing with a sponge and a little scrub brush to make the tile look as it did before I grouted. The tiles have a haze to them and the grout got in all the nooks and crannys. I kept filling the bucket with clean water to take the haze away. It’s drying now, and the jourey is out on what it’s going to look like in the morning! I know in my haste to clean the tiles I removed too much grout , I’m guessing 1/16 to an 1/8″ shallow grout lines. From what I just read above that means I need to remove 2/3 of the depth of the tile and grout again. In a nutshell THAT SUCKS!!!!!! Can you tell me where I went wrong and is the prognosis to regrout the whole floor?
Hey Matt,
If it’s TEC Invision grout you’re actually fine, as strange as that may sound.
The reason I say that is that Invision is a urethane-based grout with which you can actually go over what you have there to fill the grout lines, without scraping any out, and it will bond just fine. The trick to that stuff is to grout about six square feet and wipe it off, don’t let it set. You won’t hurt that grout at all by cleaning it immediately. Just go over it in the morning and fill all those grout lines.
If you can’t get all the haze off you need some ‘Banish’ which is a latex haze remover made by TEC. You can find it here: Banish grout haze remover
I grouted the newely set tile above my shower today and after the drying of the grout I have noticed lines that are not as full as they should be. Do I have to remove the first grout and regrout or can I put more grout over the top?
You need to scrape those grout lines out (where you need them more full) to at least 2/3 the depth of the tile, then regrout. The grout adheres to the sides of the tile, not what is beneath it.
Shower tile has grout in the corners. Can I remove the grout and replace it with caulk? If so, what kind of caulk should I use? Love your website!
Yes, you can (and should) remove the grout and replace it. Ideally silicone would be the most durable, but sanded acrylic caulk would be fine. Laticrete ‘latasil’ is a 100% silicone that you can get in matching colors for your grout.
Thank you Roger! I will do that. What is the best way of removing the grout when the joint between bathtub edge and the tile is thin?
Thanks.
A razor knife or grout saw. You can get a grout saw at home depot in the tile section.
Hi,
I recently remodeled my bathroom. I put tile on the floor and tiled the whirlpool tub. Now I see I have a slight problem. After I started to use my tub I noticed that grout in the joint when tile meet the tub is cracking. May be because the tub settled a little because of the use. The grout space between tile and the edge of tub is very narrow, so the crack line is almost invisible. I am going to treat all my grout in the bathroom with sealant, so I want to cover this thin crack along the edge of the tub. Can I use sanded caulk to do so? Do I need to remove grout from the space? Again the space between tile and edge of the tub is very thin.
Thank you.
Hi Val,
Any change of plane needs to be filled with a flexible sealant. That area is a change of plane and should be filled with either silicone or caulk. The grout will need to be removed – if it’s under the caulk it will still crack. Yes, you can use sanded caulk – silicone would be better.