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.
{ 19 comments… read them below or add one }
my husband and have recently tiled our kitchen and laundry room.it is a 35 year old house that had kitchen carpet in both areas.we removed the carpet and old linolmn was underneath.we installed backerboard thinset extra like you suggested on this site,which i read just now to make sure.now we have something like a fault line running through our grout.we did remove the grout down to the thinset and cleaned out as much as we could.then regrouted of course it cracked again within 2 weeks of the repair.i do suspect a tile is moving but is there any sure way to know if it is just that tile or more and if so what is the best way to fix it.also i am not sure why it would move with backerboard under it could it be the floor its self
If there is a small amount of deflection (less than 1/16″) in a small isolated area of the subfloor, would the use of an epoxy grout lessen the chance of the grout re-cracking?
This regular format tile has grout spacing of 3/16 to 1/4 “.
The original grout was cracking.
The original grout was ground out and replaced.
The replacement grout is debonding from the tile edges and coming loose in large chunks in some areas.
The grout itself is only cracked across one intersection in the area with deflection.
Of course the installer does not want to remove the tile to fix the subfloor deflection due to it being slight and confined to one area.
Thanks in advance for your time and comments.
Wes
Hey Wes,
What you’ve described is definitely due to movement in your tile. Epoxy grout will not solve that problem. The deflection needs to be fixed and the tile needs full support without movement for the grout to last. Epoxy grout will be very solid along the plane of the tile floor (you wouldn’t be able to pull them apart) but you will still have only 3/8″ or so – however thick the tile is – worth of support and all of that would be along the edge of the tile. It would lend no support to the underside of the tile. Eventually the stress of the tile moving up and down will crack that grout away from the tile or worse, actually crack the tile.
It doesn’t really matter what the installer ‘wants’, if you paid for a correct tile installation you apparently have not yet received that. Tell him to fix it correctly or you will have someone else do it and send him the bill. Sorry but it’s contractors like that which give legitimate people who take care of their customers correctly a bad name. I have to first convince someone that I’m an honest contractor before I even start talking about tile – because of crap like this. *Sorry for the rant*
It needs to be done correctly. If he continues to put ‘band-aids’ on it he will need to continue that forever.
Hi, Just an update on my failing shower. I had it redone with an experienced professional. Apparently any jackass can lay a floor, but only a tileman knows how to do a shower right.
Many mistakes were made in the first install too numerous to mention, but mainly: no floor pan, threshold not covered in rubber mat, no drip edges, incorrect floor pitch, faulty electrical and plumbing.
My best advice: Get an experienced tile guy for a shower, or anything to do with water.
Thanks for the advice, and I’m very glad that I had it redone right away to minimize damage.
Hallelujah!
I am so glad you decided to have someone QUALIFIED take a look at it and fix it.
And as a bonus you have the quote of the week!
“Apparently any jackass can lay a floor, but only a tileman knows how to do a shower right.”
Absolutely correct! Glad to hear it worked out even if it was the hard way.
Dear Roger,
) but I noticed one small void (less than two centimeters long and a millimeter wide at the most – sorry don’t know the ‘inches’ measurements 
) where I didn’t fill it with enough grout. Before I put on the tile grout sealer should I scrape all the grout out and regrout or could I simply scratch it open a little wider, just enough to give the new grout some purchase and regrout? I also got some grout on top of silicone (I siliconed the changes in plain first then grouted), will it just crack and fall off over time or should I scrape it off now?
I did a little first time DIY tumbled marble tiling and am really pleased with my results (rub fingers on chest
Thank you in advance for all your assistance.
Tami
Hey Tami,
You can just scrape out a little and fill it back up if you’d like. It shouldn’t be a problem at all with a spot that small. I’m actually metric literate so you’re okay.
Oops, missed part of the question. You may as well get the grout off of the silicone before you seal it – it’s gonna crack off eventually anyway. You may as well have it look the way you want rather than like it cracked off, eh?
Already stopped using shower. He didn’t realize that he had to caulk the intersections where the planes meet. He is going to remove most the grout there and silicone these joints. Should grout ever be placed OVER silicone? My other old shower doesn’t have silicone in corners, just grout, and doesn’t leak. This must be a newer code than my 50 yr old house.
He is also checking the plumbing, removing and replacing some adjacent floor tiles, and regrouting where needed.
What wall waterproofing are you reffering to? He had some black, tarp like paper in addition to the backerboard.
Thanks for all your help Grace
Hi Grace,
I apologize, I apparently am not making it very clear. The silicone in the corners IS NOT GOING TO STOP YOUR SHOWER FROM LEAKING. Your shower is leaking because the waterproofing membrane is compromised in some fashion. Grout should never be placed over silicone – it will not adhere and will crack and crumble to pieces. The black, tarp like paper to which you refer was (more than likely) used as a moisture barrier behind your backerboard. That is acceptable installation procedure for shower walls.
My concern here is that you have mentioned things such as ‘checking the plumbing and removing adjacent floor tiles’ ‘regrouting where needed’, ‘grout keeps cracking out’, ‘grout remains wet 2 days after shower’ and, of course, the biggest ‘water leaking into downstairs (from this shower)’. You have yet to acknowledge that the source of your leak is due to (short of a plumbing leak) a compromised liner. It sounds to me like you and your contractor seem to think that if he gets enough grout and silicone in all the right places that this will solve the problem. IT WILL NOT SOLVE THE PROBLEM.
The fact that your other shower doesn’t have silicone in the corners, just grout, and doesn’t leak has absolutely nothing to do with why it does not leak. It does not leak because it does not have a compromised liner in the base beneath the tile. When properly built you can take a shower in it without grout, silicone, caulk, anything, and it will be waterproof. I build showers with grout in the changes of plane – they do not leak. What substance is in the corners has nothing to do with how waterproof your shower is.
I’m not doing this to admonish your contractor, shit happens. It may not be his fault. I don’t know. I don’t care. The fact remains that, unless your plumbing has a leak, your shower is leaking because your waterproofing membrane in your shower floor is compromised. Everything you’ve described to me points right to it (cracking grout, wet grout, LEAK). Tearing out adjacent floor tiles, checking the plumbing, replacing grout at the plane changes with silicone, all these are fine. But short of the aforementioned plumbing leak, they do not change the fact, nor will they, that your shower floor is leaking.
I apologize for being an ass but there does not seem to be concern to an extent that warrants properly solving the problem. I’m saying there needs to be. If there is not this problem will compound into something much larger. The solutions that are being suggested are akin to cutting your arm off with a chainsaw and placing a band-aid over the wound. It’s not going to hold – knowwhatimean? The solutions being suggested are not going to solve the problem – period. You have water leaking downstairs, would you place a garden hose in your window and turn it on very low for 10 minutes twice a day?
I really don’t know how else I can say it. Your shower waterproofing membrane is somehow compromised – leaking. Short of diagnosing exactly how and fixing that problem everything you do is for naught. The rubber waterproofing membrane below your mud deck in your shower floor needs to be repaired or replaced. I don’t know how else I can explain that. Sorry if I sound like an ass. If it saves thousands of dollars worth of damage to your house – I’ll be an ass.
My problem is similar to Vickis. New shower & floor. 2 months in, grout keeps cracking in corners and now leaking water to downstairs. Contractor used backer board, mud mix on floor and some kind of rubber floor mat under tile. Sanded grout, and it is greater than 1/8″ wide. He “repaired” it once, by grouting over the cracks, but that didn’t last. What do I need to know here? This is a 50 year old house, first time bath re do. Also, maybe this is important, the grout that gets wet during a shower, takes 2 days to return to a dry appearance. Its really noticeable because it is beige and then turns and stays dark beige when wet. Is this bad grout? It was sealed twice before use.
Hi Grace,
Stop using that shower! Seriously.
I’ll start with the easy answer – no, it is not bad grout. Grout and tile are not waterproof. They never were and were never meant to be. Your shower should be absolutely waterproof before a box of tile is opened. Your shower, obviously, is not.
The fact that your installer attempted to repair cracking grout by grouting over cracks speaks volumes about his (lack of) knowledge on the subject. Applying sealer to tile and grout do not make it waterproof either – see above.
It sounds as if there is actually a waterproof membrane (the ‘rubber floor mat’) beneath your floor tile but it obviously is either cut and re-glued in the corners or simply installed incorrectly.
The fact that your grout remains wet 2 days after a shower and that he used backerboard beneath the liner tells me that there is more than likely no pre-slope beneath that liner. Water sitting at or below the top of the drain will do just that – sit there. As it slowly evaporates (not all of it ever will) it will force your grout lines to remain wet as this is where it evaporates through.
Is your grout only cracking in the plane changes? That is the floor-wall connection, where the walls turn, and any other change of direction of your plane of tile. By code any changes of plane need to be caulked – not grouted. If your grout is cracking on or around your curb that is a moot point.
Now I get to be the ass again. I hate that…
You have stated that you have water leaking to the downstairs. Your shower is built improperly. The membrane has failed in some respect allowing water to penetrate below the liner through the floor or into the wall behind it. If you continue to use the shower the problems will get worse, compound, and my dog will burst into flames. Please don’t do that to my dog. The wall framing around your shower (I’m assuming they are wooden 2 x 4′s and not metal studs) will actually ‘wick’ water just like a candle. It will swell, deteriorate, and cause unseemly amounts of damage to not only the tile and shower, but to everything else around and below it.
Think Grand Canyon – water carved it. I understand that is an exaggeration of possible damage but I do not want you to underestimate the amount of damage that can be done by an improperly built shower.
You need to have a qualified professional look at and assess the shower and what will be required to properly fix it. At the least I would guess the floor and at least two feet up the wall will need to be torn out and properly replaced. You haven’t stated how, or if, he waterproofed the walls but that needs to be taken into consideration as well.
Sorry to be the bearer of bad news (again). I’m getting real good at telling people what they need to hear rather than what they want to hear. Feel free to leave any additional information or questions here or, if you’d rather not discuss it in front of the entire world, you can email me at FloorElf@FloorElf.com to discuss what you will need to do to get this resolved. You can also read through my site to discover what should have been done in the process of building your shower.
And, as a bonus, if you send me your ‘contractors’ address I’ll send Guedo after his ass to have a little talk with him.
I just had my master bathroom completely redone, and today I was flipping through channels and they were talking about a vapor barrier, I know the contractor put tile on top of green board for walk in shower w/ backer board for floor as I checked progress everyday for the 5 months it took him. What do I do now? The bath is finished about 3 weeks old, Can I seal every month to avoid water problems or it is this a lot bigger problem, spent about 18,000+ on this also just noticed today that the raised edge to the walk in shower the grout is cracking I believe has non sanded grout what to do now?? My husband was so upset this took so long, and now will be really upset if we have to have redone.
Hi Vicki,
Sorry to hear about the problems. I’ll need to clarify a few things first before I can (hopefully) effectively help you out.
1. What part of the country are you located? I ask because in most (and it should be all) areas by city or county code, as well as anywhere by TCA standards, green board is not an approved substrate for tile. I assume that the ‘green board’ that you are talking about is in fact the (almost) regular drywall with green paper backing? That is green board but there are also two products that people call green board that are, in fact, not green board.
2. What did he use to adhere the tile to the wall? Was it a powder mixed with water (thinset – correct) or a pre-mixed product in a sealed bucket (mastic – absolutely incorrect)?
3. I assume (and hope to high hell) that you mean he used backer board on the regular bathroom floor AND NOT for the floor of the shower which requires a dry-pack mud mix. Is that correct?
4. How big are your grout lines? If they are 1/8″ or smaller it may be unsanded grout in which case it may just be shrinking. If they are larger than 1/8″ he used (incorrectly) unsanded grout in which case it is probably still just shrinking but should be replaced with the correct type of sanded grout.
Sealing your tile (even every month) will NOT make your shower waterproof. A shower should be waterproof before a piece of tile is touched. If it is not it is incorrectly built. Sealer is made only to prevent tile, stone and grout from staining. Not only that – if you paid $18000 to have your bathroom remodeled you should never need to ‘waterproof’ your tile – ever. Let alone every month.
If you could answer the above questions for me I can help you determine what your next logical step should be and whether or not I need to send Guedo
after your contractor.
Roger, is it possible/practical to remove a grout that is considered too light for the slate and replace it with something of a similar colour to the stone? I grouted the stone a few days ago, but I’m not happy with the colour.
When I bought the slate for my bathroom, I asked for grout samples, but they couldn’t provide them, so I asked their technical guy which one they would recommend if I wanted one to at least roughly match the slate in colour to give a homogenous look. They advised PCI groutfast 8 grey, so that’s what I bought. When mixing the grout I did notice that the grey was quite light, but I just assumed it would darken when dry because I trusted that they would have advised me correctly. However, it only got lighter, and it’s not from surface laitance because if scratched it’s a similar colour deeper down. The grout is so light compared to the slate that you hardly even see the stone, you notice the light grout lines, which is the opposite look from the one I was going for, unfortunately.
I’m concerned that if I dug out the grout and regrouted in a new colour, light bits would still show along the edges of the tiles where old grout still remained. Your advice would be appreciated
Hi Al, sorry to hear about your problem.
There are a couple of solutions to your problem, one being to remove and regrout. Before doing that, though, you may be able to darken the grout by using an ‘enhancing sealer’ made for stone.
This particular type of sealer is made to bring out the different shades and natural color of the stone and will usually do this by simply darkening it. If you wipe your slate with a sponge the slate will darken and enhance the natural coloring – enhancing sealer does the same thing but locks in the color change if that makes sense.
In doing this it will usually darken most cementious grouts at the same time. If you don’t want that look for your stone you can apply the sealer to only the grout and see if it will darken it. It may or may not, that depends greatly on the chemical makeup of the grout as well as the sealer.
If that does not work your next best option would be to regrout it. After you remove your grout you can get a ‘rubbing stone’ made for tile. It is made to ease the edges of cut stones. It basically ‘sands’ down the edge so it isn’t sharp. It will, however, remove grout as well. You can place the corner of the stone (get a square or rectangular stone rather than the round) into your grout line after you remove what you can and lightly rub it back and forth to remove any grout that may remain in the upper portion of the grout line.
That won’t remove any grout further down into the grout line but it should remove enough so that when you regrout it with the darker grout none of the lighter stuff will show.
Hope that helps. Let me know how it turns out so I can perhaps help someone else in the future with the same problem. If that doesn’t work let me know that, too. Knowing what doesn’t work is just as helpful as knowing what does.
Thanks for the advice! The bathroom is finished and looks sensational.
The sealant made the grout darker when wet but it was the same colour when dry. No-one seemed to sell rubbing stones. I read someone on a forum say he now uses diamond sandpaper instead. I didn’t get any of that either though, instead I just used a grout rake to make a deep v shaped groove in the grout, then I’d angle it by resting on one edge to grind the grout off the other edge. The tiles ended up looking scratched, but when wiped with a damp cloth I could see that the grout had been sufficiently removed.
I did not reseal the scratched tiles yet, because I wanted the new grout to have every opportunity to stick in what little cracks the old grout was still hiding in along the edges. When regrouting, I tried to keep it as flush as possible with the tiles. They, when it was finished, I resealed and the scratches in the slate ‘disappeared’ once darkened the same colour as the rest of the slate. Not one piece of white showing, success! Thanks
P.s. why not put a little bar of google adverts at the top or bottom of your site? That should give you some extra revenue to help reward your efforts, without ruining the look of your wonderful site.
Hey Al, Glad to hear it worked out! Sometimes the sealer will work and sometimes it doesn’t, like I said it depends on the chemical makeup of the grout and the sealer. Good to hear you got the finish you were looking for.
I’ve thought about google adwords but the problem is I have absolutely no control over what products are advertised on my site. I don’t want ads for crap products and have people somehow think I’m endorsing them. And there are a lot of crap products out.
I am going to open up a little online store here when I get everything together. People will be able to order the stuff from me that I recommend here – you know, stuff like a rubbing stone. Seems that for some reason it is not as available as I thought – I may as well make it so.
What I would like to do is to obliterate the grout lines between ceramic tiles enabling me to combine four tiles and paint over them creating one large square tile where previously there were four. I want a more contemporary look to the bathroom wall. I would even like to rough up the tile surface before painting for a two-toned effect. Is all this possible?
Hello Virginia,
I’m not sure what size tiles you currently have or whether they are already installed (I’m guessing yes). To “obliterate” the grout lines you would need to essentially float the surface of the tiles to be consistent throughout. It is not simply a matter of filling the grout lines with something.
If you notice the edges of your ceramic tile they actually taper down as they approach the edge. When installed this leaves a smooth taper down to where the grout line is created. To do what you want you would have to fill this portion of the tile as well to get a surface that looks like one large piece. Not sure how practical that would be but yes, I guess it is possible. (on a wall) I wouldn’t be able to recommend what to use for it, though. You need a product that would actually permanently adhere to the tile face. The only thing I can think of would be an epoxy based product. Bondo maybe? I wouldn’t do it but it’s not my house, eh?
If the wall you are speaking of is in a shower – don’t do that. It will not last.
You will need to rough up the face of the tile to paint it anyway. Make sure you use a paint that will properly adhere to your tile as well as withstand the environment.