Shower grout problem

[doityourselfer]

New to the website and forum, thanks for all of the great information. I saw a similar thread below (grout in corners of shower) but had a slightly different question.

We moved in to a new house and our master bathroom shower is developing dark discoloration of the grout after about a year (worse in the corners). It's been about a year so it's time to re-seal but I don't want to seal over stained grout. I've tried various cleaners and solvents without much improvement. I should also mention that before moving in to the house, an inspector recommended the shower base be waterproofed...my fault, I didn't look closely at this when we moved in and it looks as though they just went over the regular grout with some caulking, or possibly an acrylic grout. This outside layer started to peel off after scrubbing the stains with a grout brush. I've read that caulking over grout can cause some moisture retention issues (is this why I'm getting discoloration?).

I'm willing to do whatever it takes to fix the problem, including regrouting, just want it done right. Any recommendations would be greatly appreciated. Thanks.

[jadnashua]

Do you have an exhaust fan? If so, do you use it? Is it darker like wet grout, or mildew? Is it darker on the side opposite of the showerhead? or allover? Worse down low or anywhere on the wall?

Sealer does a couple of things: makes the grout absorb less water, and makes it easier to clean up. Caulk over grout is indications of a bandaid attempted fix to a problem.

If you press on the wall, or walk on the floor, is there any flex? Any indication of moisture outside of the shower or on the ceiling from below?

At the changes of plane (wall to floor, wall to wall) it should be caulked. If properly constructed, you might get by with grouting those places. It often will crack grout in corners, that's why caulk is specified.

[John Bridge]

Hi and welcome. First thing, give us a first name.

I would say the stuff over the top is causing the grout to retain water round the clock, which will inevitably allow mold (mildew) to take root. It's the black stuff.

I would remove all the surface stuff (which could be clear silicone or some other type of caulk), and let the grout dry out. Then you can clean it by either removing and replacing or by scatching its surface.

[doityourselfer]

Thanks for the helpful advice. My first name is Eric.

The discoloration is more dark brown than black (the grout is an off-white color). It looks as though it's constantly wet, but the corners and base are significantly darker than the surrounding grout, even when wet. I removed the overlay caulk and will see if this helps.

Jadnashua, unfortunately, there's no exhaust fan (we've been cleaning the shower after each use with a squeegee and leaving the door open to let it air out). The only dark areas are where the walls meet the floor, particularly in the corners. No flex that I can appreciate. No other signs of moisture.

If caulking should be at the changes of plane (wall to floor, wall to wall), should I remove the grout from these areas and re-fill with caulking? They're currently all grout...with the exception of the the overlay caulking around the floor that's peeling off. Thanks again!!

[jadnashua]

If the joints aren't cracked...leave it alone and be happy. Often they do crack, that is why the recommendation is to caulk. It is possible that the pan was not made per current specs; doesn't mean that is is leaking, but not draining as well as it should. Many installers seem to think tile and grout make a waterproof surface and only slope the top of the floor. If you read the shower pan installation instructions in the "liberry" link in the above blue bar, the actual waterproof layer must go over a sloped base. If you don't do this, a little bit of moisture will migrate down through the grout/cracks/etc. and instead of finding a way to the drain (there's supposed to be a second opening - weep holes to the drain under the top grill) will accumulate under the floor. That could be a reason you floor and lower walls look wet...they are sitting in a pool of water under the floor.