Does it get smaller when you stop using the shower for an extended period of time? Can you take another view to show the glass and the floor? It does look like a leak.

Thank you for responding, enduring. It does NOT seem at all related to use of the shower, which is why it's confusing. That is sealant, not water, on the edge of the photo, BTW. It absolutely does look like something that would be caused by a leak but cannot find the origin of such.

Water finds the lowest spot so the source of a leak is not always apparent. You should allow the contractor to remove it to replace and have a moisture detector present to access if there is a leak causing the stain or indeed a sealant issue.

Very pretty tile! I would love to see more of your bathroom!

Very neat looking shower BTW

STOP using the shower and let the eitire room dry out. You will solve the wet VS sealer mishap riddle..

Look closer at glass and glass channel and possible screw holes from glass install as the source of slow leak if my first bit of advice proves to dry out the concerned area.

Dont rule out a copper or pex pipe leak below that area in a joist bay if its A possible water line location but you wouldof found that already?.

Dont rule out wicking. Believe it or not water can wick up a fleece membrane from a pan floor over the curb and out the other side if it has a path. but you would have seen that if and are you saying you had A flood test AFTER tile install and had a plumber insert a proper plug @ fill the pan up to the curb after concerns of leak? and you didnt mention....is it a steam shower?

I'm curious how that shower glass works. Can you step back and take a large picture of the whole corner and both sides of the glass. Is that a sliding glass door?

Thank you, everyone. I am going to stop using the shower for an extended period, but I suspect the mark will remain. This installation has several issues, but I didn't want to ask too many questions at once ....the shower door (which is on a hinge, opening out) has a small leak near the hinge and the sweep isn't functioning properly.

As well, the ledge doesn't have enough pitch, so water sits for many hours. I am not happy with the mosaic look inside the shower stall and am thinking of

pulling it up to see what it beneath and also considering the installation of porcelain tiles, which will need less babysitting.

The reason that I asked about the exterior mosaics is that I have been studying

the patterns for months and do not ever see water sitting where the mark has formed, which is why I came to you for help. This really does not seem to be

related to the other problems mentioned above and it is a conundrum for me and my team. Waterworks has not seen it in person, but they seem very interested in calling it a day by terming it clearly a sealant issue. If that were true, it would seem that these marks would form where water does escape the shower, but that is not the case.

Oh, and to address two questions from Tundra Works: yes, our plumber inserted a proper plug as described and it is not a steam shower.

If this is a water issue, I was guessing that it was coming from underneath, not from the topside. However, I was wondering about dripping from your door, possibly causing standing water soaking in.

Gloria,

Just to clarify, the flood test was done after the tile install? Do you have any pictures of the shower as it was being installed so we can see the condition of the waterproofing?

I'm leaning toward enduring's scenario. Shower door gaskets,sweep or hinges. I have seen similar visuals caused simply by the water dripping off the door when opened after a shower. If there is grout against the shower base instead of silicone sealant a hairline crack will usually develop allowing water to go straight down to the substrate which would become saturated with daily use. Just a thought.

The flood test was done after the tile install. I'm sorry that I don't have any pictures of the installation but I will see if the contractor has any. There is no question that work needs to be done on the door/ledge pitch and sweep but

I have NEVER seen the area in question outside the shower wet. I have studied that

endlessly, but water doesn't settle in the spots with the stains. I wish it were otherwise, because at least then we would know what corrections might work.

Water would beneath the tile and wicking up. You would not necessarily see water pooling or puddling.

I'd put a Bernz-O_Matic torch on that splotch near the corner.

Get a small, cheap fan, and direct the air at the dark spot. Stop using the shower for a couple of days.

Tough to say as mentioned above it very wellcould be thru a hole in the curb that was not caulked properly. You mention that the angle is not correct. Thru the curb behind the tile to the floor, underneath the tile and then wicking up.

I have no advice. Your floor is magnificent. I am sorry you are having a hard time getting this last bit right. I wish you a speedy resolution to the issue.