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.

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.

Theresa

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

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.

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.

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.