New shower has grout discoloration

Paula_1997November 28, 2012

We recently completed a bathroom renovation. After using the shower only about 3 times I noticed grout discoloration -- black like it was wet or moldy even after letting it dry out for a week. First my architect told me to clean it with a dobby sponge, which I tried but that did not work. We didn't use the shower for at least 2 weeks in a row to see if it would just dry out and return to normal color but it did not improve. Then he sent a tiler to acid wash the grout. After washing 3 times, the shower mostly looked great, except a pretty large section on the vertical rise to the shower bench and a few small spots on the floor around the perimeter. (Once again we did not use the shower during the 10 days or so that this was going on.) So about a week and a half ago they regrouted the some of the discolored grout on the vertical rise to the bench. Those same spots stayed wet looking but they told me to go ahead and use the shower (which had lost its sealer because of all of the acid washing) so that we could see what would happen. Nobody knows why these spots are staying discolored. They have told me that if this doesn't work they will bring in some company called "Grout Doctor" that basically paints an epoxy over the grout to make it look nice. My impression is that this is a service for old dirty grout when people don't want to spend the money to retile/regrout, NOT for a brand new shower. I think I have seen bathrooms where this has been done and they look terrible after awhile as it peels off. But I don't know what to ask them to do short of retiling the whole thing?? I would really appreciate any ideas both as to what might be causing this discoloration and what I should ask them to do about it. Also what is your opinion about their Grout Doctor solution?

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I don't know enough about your shower to provide positive guidance.

Dark grout is usually a sign of water absorption and/or intrusion. It can sometimes show a dark grout around the perimeter of a floor, sometimes with moisture wicking up and darkening the grout in the lower walls. But that usually occurs after more than just a few showers.

It can show as a dark ring around the drain.

Sporadic dark spots on the floor could be due to slow draining "bird baths", or slight irregularities in what should be a nice continuous floor slope from wall to drain.

Built-ins like benches can be hot spots if they were improperly detailed during construction.

It's tough to say what your problem is.

The typical first question is: Did they install the waterproof membrane in the shower floor on a sloped surface or was it installed directly on the flat subfloor?

An overall photo of the shower might help.

    Bookmark   November 28, 2012 at 8:44PM
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Do you know (have photos) of how they built and waterproofed the bench, and the wall above it? Was the bench pre-sloped before the waterproof layer?

    Bookmark   November 28, 2012 at 10:43PM
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I will try to post a couple more photos but they keep coming up sideways. I don't have any photos of the shower in progress. We used a reputable contractor who is trying to fix the problem without ripping it out. I am sure it was all waterproofed and sloped but there is always the possibility something isn't right underneath. I was just hoping someone may have seen something like this before.

    Bookmark   November 30, 2012 at 3:32PM
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This is a view of the shower overall

    Bookmark   November 30, 2012 at 3:34PM
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Hi, I had this problem almost 5 years ago and had a lengthy thread about it. Another reader just emailed me about this same problem and had read my thread. Here is a link to it. the problem ended up being the mortar mix was not right. I also had a stone tile installation. My pictures of the problem are still on the thread. I hope this helps! DO NOT use Grout Doctor!!

Here is a link that might be useful: Help! Grout Discoloration on New Shower Floor

    Bookmark   November 30, 2012 at 11:24PM
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