Just realized I've been cutting all my grout lines wrong for 3 years

I was at a friend's house last week, his bathroom reno from a pro crew. Looked at the tile floor and something felt off. Then it hit me. My grout lines were all too deep. I used to clean out grout with this little tool until I hit the backer board. Thought that was how you do it. Turns out you leave like a quarter inch of grout in there. That shallow layer keeps water from pooling behind the tile. No wonder my last three backsplash jobs had mold spots after a year. Friend's have a buddy who's a tile setter, told me straight up. Now I gotta fix the bathroom I did in October. Has anyone else had a dumb revelation way too late in the game?

3 comments

3 Comments

murphy.abby1mo ago

Wait are you serious @derek_perez, that's not even about water?

derek_perez1mo ago

Yeah but I think you're mixing up two different things here. The depth of your grout line isn't really about water pooling behind the tile, that's more about having a solid waterproof membrane underneath or using the right thinset. You definitely don't want grout so deep it hits the backer board though, that just makes it weak and likely to crack out.

emery_white1mo ago

Haha right, "don't want grout so deep it hits the backer board" - that's like the grout equivalent of digging to China. I mean sure, nobody wants a grout line that's basically a gaping canyon, but at this point I'm starting to think people might just be overthinking the whole thing. Maybe just keep the grout reasonably deep and stop trying to make your bathroom floor some kind of engineering marvel.