Hot Topics: Grout

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Original Post: Grout Sealant for Truly Waterproof Grout?

StarSeeker Member

I've used a couple different kinds of grout sealer in the past. I would consider it "better than nothing," and might even be fairly effective at resisting stain, mold, and other problems. However, waterproof, it was certainly not. Pouring water on sealed grout still soaked in; just a bit more slowly than before.

I'm looking for a grout sealant which is either totally or at least nearly totally waterproof. Something more in line with what you would get if you smeared silicone caulk into the joints or painted it with weatherproof paint.

Alas, most grout sealants don't boast of being any more "waterproof" than any of the others.

I'm wondering if something like Thompson's Water Seal would work well for this purpose? Or is there a grout sealant with that level of waterproofing? Any recommendations?

For the record, I'm looking to seal ¼ inch existing grout in a spare bathroom where the cats' litter box is kept. On occasion, they've been known to miss or kick litter out of the box and use the resulting piles. Keeping cat urine out of the grout is very important (making it easier to clean in the process). To this end, I'm looking for a less obtrusive sealant for the ceramic (porcelain?) tiles to make them easier to clean as well.

Top Comment:

XSleeper Group Moderator

You would have better luck with different grout that actually has an additive that makes it moisture resistant, like Mapei Grout Maximizer.

Painting a sealer on the surface is just not as good.

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Original Post: Problem with Floor Grout Crumbling

andee1517 Member


I had my kitchen floor recently replaced with porcelain tile. Right after they were finished I noticed a couple of areas where the grout did not look right. The rest of the floor looks beautiful. They assured me it would be fine after it completely dried and if not they would come back. After a couple of days, it still looked the same so they came back and redid it.

Of course, the next day it still didn't look right. There were little holes in some places (appeared that not enough grout was put down) and crumbling grout in other places. Now the tile guy is ignoring me even though he said he would come back to fix it yet again. I've read some other stories here of folks with the same issue. Not sure what I need to do now. I saw the sub-floor when they removed the old tile and it looked like, for lack of knowing the proper term, floorboard and they told me it was good for laying the tile on top of. I know he used thinset to lay the tile. He also mentioned after I called him back this last time that "this is going to happen because there is no concrete under the tile." Well, he never mentioned that would be a problem when they started nor did he offer any type of solution to alleviate any issues. So annoying!

I had a friend of mine regrout the spots but unfortunately the same thing happened. I'm wondering, could humidity be causing problems? It is super hot in my kitchen although again this happened from the get-go and the majority of the tile looks great. Should I buy another bag of grout? This tile is in the middle of other tiles in a well-trafficked area (I have a small galley kitchen). Do I need to have the other tiles around it removed and laid again? Man, I really don't want to have to do that. I've read also movement could be causing it.



Top Comment:

Pilot Dane Group Moderator

You need concrete, Hardie Backer, or cement board. Wood of any type is not a suitable base for tile.

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Original Post: Grout Cure Time

marksr Forum Topic Moderator

I just got done grouting the new tile in my shower. The label on the unsanded grout says it can't be flooded with water for 21 days. What does that mean? I know the wall tiles won't be underwater but expect water would run down them during a shower. How long do I need to wait before using the shower?

If I remember the last tub surround/shower I did I used the shower the next day although that was close to 35 years ago.

Top Comment:

czizzi Forum Topic Moderator

Grout needs to cure 72 hours before sealing. Seal it with a quality grout sealer. Test it. If the grout darkens when moisture is applied, then you need to reseal it.

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Original Post: Shower Tile Grout Turning Orange

penguoctopus Member

I recently had to chip out some old grout to do a few replacement lines in my shower. Some of it was orange, and I figured regrouting would get rid of the color. I've tried re-applying it twice now, and both times (after about three hours of dry-time), the grout in some spots is turning orange/brown. It's as if something is seeping. I left the spaces open the other day for about 8 hours just to see if any rusty liquid or seepage would show up and saw nothing. I even ran a paper towel in there and still nothing. I haven't used the shower in days.

Anyone out there know what this might be caused by? It's driving me up a wall. Any help is much appreciated!

Top Comment:

Pilot Dane Group Moderator

I assume there is iron under there somewhere. It might be in the old grout or under the tile. It doesn't take much. I would dig out the grout in that area. Be careful as a steel tool can scratch off onto the unglazed part of the tile. When you first do it, it looks like a gray mark almost like a pencil but when it gets wet it rusts and turns a reddish-orange color.

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