Your grout is cracking for one reason and one reason only: your tile is moving. That’s it. Okay, that’s not it – Unless your grout is non-sanded and was installed in the last 28 days – your tile is moving. That’s it. Yes, 28 days has significance, it is the amount of time it took my teenage son to clean his room. It is also the amount of time it takes for grout to fully cure.
So let’s figure out why your grout is cracking:
Your grout is newly installed – incorrectly
If you do have grout that was installed within the last 28 days then your grout is not actually cracking – it is shrinking. Either your grout lines are too large for non-sanded grout (smaller than 1/8″) or it was incorrectly mixed. NO! You cannot simply mix up more and fill it in. Read this post about adding more grout to your grout lines.
If your grout is not fresh, well, you need to repair the reason your tile is moving. And stop using your pogo stick in the house. Diagnosing the reason your tile is moving is extremely varied. It could be anything from inadequate deflection in your flooring for the type of tile all the way up to and including the aforementioned pogo stick.
The most likely reasons your tile is moving:
Your tile does not have proper thinset coverage
The most common reason I run into is improper coverage. This simply means that there is not enough thinset beneath your tile to properly adhere it to your substrate and support it. If there are any unsupported areas beneath your tile along the edge or in the corner of the tile, walking on it will eventually work what little support it may have loose and the tile will move down and up every time you step on it. The tile moves, the grout does not. The grout loses the battle and starts to crack out. By ‘crack out’ I don’t mean like that ridiculous Intervention show on cable, I mean it will start to crack and come loose.
To fix this you need to remove and properly reinstall the tile. If it is only one tile it may be an isolated incident in your installation and you will be fine. If you have cracked grout all over your tile installation it was either improperly installed or . . .
Your subfloor is moving
If you have a wooden subfloor and your tile is directly installed to it – go pick out new tile. That is more than likely an improper installation. While tile can be installed directly to plywood it requires a VERY specific method. And I do mean very specific. More than likely it is simply installed improperly probably by someone that did not know any better. If it was properly installed over plywood, well, your grout wouldn’t be cracking. Start reading this paragraph all over. Or . . .
Your backerboard was improperly installed
If you have Hardiebacker, Durock, or any other type of cementious backerboard beneath your tile it should have been installed in the proper manner. It needs to have thinset beneath it, it needs to be screwed down (properly), it needs proper spacing, etc., etc. Read How to Install Backerboards for Floor Tile to see all the things that should have been done.
More than likely there is no thinset beneath your backerboard. Thinset is not used to adhere the backerboards in any way – it is used simply to fill voids beneath the backerboard. It is placed there specifically to prevent your tile from moving. Moving tile leads to cracking grout. But you knew that – or you should start reading this page all over. This would be another time to start shopping for new tile.
Other reasons your tile is moving
You do not have expansion space around the perimeter of your tiled room. No, the tile will not expand – but your walls do. If there is no space between your tile and walls it will force all the pressure into your tile. This will cause cracking grout and, eventually, ‘tenting’ of your tile.
You do not have expansion joints in your tile. For every application there are specific spans of tile which can be installed before a ‘soft joint’ is required. This is simply a grout joint filled with a matching caulk or silicone to allow for movement without cracking your grout or tenting your tile. Most of these measurements are over 25 feet. So in English: if your room is not 25 feet long or wide this is not the reason your grout is cracking.
If your tile is on concrete – directly on concrete – your slab may not have proper expansion joints or the tile installation did not honor those. If installing tile directly to concrete (and you should not) there needs to be a soft joint directly above, or two inches on either side, of the slabs expansion joints. If not your slab will move differently than your tile.
And there could be a host of other, less apparent or less common problems. However, if your grout is cracking it is probably for one of the reasons above. The method of repairing it depends entirely on why it is cracking. Most of it, as with most tile installation problems, is due to improper installation.
Or your pogo stick.
If you have any questions about the proper way to repair your tile or grout just leave a comment. I answer every one of them – really, look around the site. I’m just super cool like that.
{ 10 comments… read them below or add one }
I’ve had some tiling done in back entry way, bathroom and laundry room. I’m finding small hair line cracks all over. I had a professional Tiler put it in…he fixed one area…took the grout out and put it back in. Now, I’m finding little cracks all over the floor, including the area that he fixed!!!! Should I get a second opinion from another tile installer….should I have him just replace all the grout…or should I have him redo all of it? Can you reuse tile that has already been layed or would I have to buy new tile?
Theresa
Hi Theresa,
This could be one of two things. It could be either incorrectly mixed grout or movement in the substrate. Since you said he has already replaced some of it and the same thing happened I think it is the latter of the two. That would mean the tile should be taken out and replaced on a properly prepared substrate. 95% of the time – no, you cannot reuse tile that has already been installed.
You should get a third party to take a look at it and see what is happening. It’s really the only way to get a definitive answer as to what is actually happening.
Hi Steve,
My husband and I installed a tile floor in our bathroom over a year ago. We used 3/8 concrete backerboard screwed down to the subfloor every 6 inches, 1/4 by 12 inch ceramic tile with sanded grout lines 1/4 wide, with thinset very carefully mixed to medium-thick pancake batter consistency. Our grout lines are starting to crack along the entire length of the seams, and one area of grout in a traffic way has started to come up in little chunks. Certain tiles are definitely loose, and we really need to get this fixed! Our house is less than 10 years old, and is still settling, so we think that is probably the cause. How can we go about fixing these grout lines? Is there any way to allow for settling?
Thanks,
Marie
Hi Marie,
It sounds like a combination of two things causing your grout problems – the house settling being neither of them.
I could be wrong (just ask my wife – she’ll tell you) but it sounds like you did not use fiberglass mesh tape over the seams in the backerboard – that’s why it’s cracking along the seams. The individual pieces are moving independently. And it also sounds as if you did not place thinset beneath the backerboards to fully support it.
Unfortunately the only viable solution is to start over and properly prepare the substrate with thinset beneath the backerboard and alkali-resistant mesh tape over all the seams to give you a monolithic, fully supported substrate for your tile installation. If the substrate moves or is not fully supported the grout will crack, tiles will become loose and begin to move and, eventually, tile will start to crack.
I used a sanded grout with polymer by Keracolor, and used 1/4″ spacers. How would I be able to tell if there is movement? I layed hardiebacker cement board over plywood, and put screws in per manufaturer spec in an 8″ by 8″ pattern throughout each peice of backer board. I feel confident that I used enough mortar under each tile. It has only been 2 months should I give it more time to see if it begins to crack in other places? Or is there already enough evidence that it is indeed pulling away due to the dreaded shrinkage. If this is the problem do I have to replace all the grouting or just where the grout is pulling away. Thanks allot for help, I really appreciate it.
Hey Shawn,
The best indicator of movement is the grout actually cracking out of the joint in pieces or turning to powder from being literally ground into dust from the tiles rubbing against it when they are stepped upon. If the grout is still in one piece (ie none has cracked out in chunks) then it’s likely that it is only shrinking. If there was not ‘soggy’ or brittle, soft plywood under any of the areas and you placed mortar beneath the backerboard before screwing it down it is probably not movement.
The two things that you’ve described that lead me to believe it is shrinking is that they are ‘cracking’ in a straight line and only against the tile edge and the fact that you mixed more water with your grout. If it were due to movement the straight line would be very rare – it’ll crack all over the place randomly. It would be best to replace it all but you may be fine just replacing what is shrinking. If you do that, though, be aware that more of it may shrink in a different area later on down the road.
I installed new tile floors in my upstairs bathrooms the first week of May 2010. I recently noticed the grout lines are cracking in both bathrooms. The grout is cracking along a line from end to end in a series of tiles that stretches from wall to wall. They differ in lengths from 3 to 6 feet. I’ve looked online at similiar situations. I’ve come to the conclusion that I didn’t pack the grout lines deep enough, and/or when I was grouting I was using grout that had hardened and I would add water to make it the right consistency. In speaking with a friend I’ve come to find out that is a bad idea. The grout is not crumbling it is actually cracking away from the edge of the tiles and it runs from end to end consistently. I am starting to think I did not pack it in enough. What do you think, and how should I fix it?
Hi Shawn,
You did not state whether you used sanded or unsanded grout for your floors. If it is sanded grout and your grout lines are wider than 1/16″ then it should be removed and replaced with sanded grout. If you used sanded (and added water to the mix) it may have indeed shrunk on you. You need to ensure there is no movement in the tile but if it is simply pulling away from the tile and not crumbling or turning to powder it sounds like shrinking to me.
The correct and best way to fix it would be to remove all that grout and replace it with new grout. Never add more water to the grout once you mix it, it weakens the grout and will cause shrinkage (that’s a word, Seinfeld says so). I know it’s counter-intuitive for us guys but follow the mixing directions on the bag – including the slaking. If followed correctly you should have plenty of time to get it grouted without it getting hard in the bucket.
I have a tiled upper deck above rooms below. I have sealed the grout which the contractor failed to do and stopped most of the rain from causing damage below. I now have a prolem where the open tile deck ends and a metal corrigated roofing starts I have repeadedly used grout but after drying it cracks. Do you reccomend a drywall tape before caulking or grouting this seam? It is about 20 feet long and about a quarter inch wide gap. Regards Steve
Hi Steve,
Tiled decks are a very special animal. When transitioning from one material (tile) to another (corrugated roofing) there needs to be a movement joint of some type starting below the tile in the form of an anti-fracture membrane or uncoupling membrane, and transferred through all the way to the top plane of both materials. The upper portion of this would be either a 100% silicone or a urethane-based sealant – grout will not do it. It is cracking for the same reason as most – movement.
Any joint between two different substrates needs to allow for different expansion and contraction of the two materials – they will move differently. The tile may (will) expand more slowly and less than the corrugated roofing as it gets warmer. The problem has nothing to do with water unless freezing is an issue. It has to do with movement control. You need to allow for a different expansion rate at that joint between two materials.
Drywall tape will do nothing for you. The last row of tile should be removed, an anti-fracture membrane installed, and the tile replaced, then that joint needs to be caulked with a flexible sealant. You have three different things pushing on your grout from different directions and at different pressures – no type of regular grout will withstand that. It needs flexibility. You can attempt to simply remove the grout and fill it with a flexible sealant instead without the anti-fracture membrane but in the long term it may not last – I don’t know without having specifics about your particular installation. Go ahead and try the flexible sealant, if your tile was correctly installed you should be fine.
Now, with all that said (typed), if you have a leak in that porch and it is compromising the ceiling no amount of sealer will be a permanent solution – your tile is installed incorrectly. When correctly installed your porch should have been absolutely waterproof before a piece of tile was touched. Substrates like porches over living areas and showers are always waterproofed at the substrate. You should be installing tile essentially in or on a waterproof box. If you are attempting to waterproof it by placing materials or products over the top of your tile it is incorrectly installed.