All changes in plane should be caulked, not grouted. Remove the grout with a hand held grout saw and replace with sanded caulk that matches your grout.

Where the curb "bulges" into the shower...was that always like that?

If not, it's usually a sign that the curb was constructed with a wood core, that water has gotten into the curb, and now the wood is expanding due to being saturated with water.

The source of the water? It could be an improperly installed membrane at the curb. One where the installer draped the membrane over the curb, then fastened tile backer board to the curb by driving fasteners right through the top and sides of the curb, puncturing the membrane.

Or the membrane and tile over the curb could have been properly installed, but then someone drove fasteners through the membrane (example, the screws that secure the bottom hinge of the door).

Over time water can get through grout. If the membrane is punctured, that same water can wick into the wood core of the curb, cause it to expand, and blow out the tile and grout.

If it was just the grout cracking, then yes, I'd say the easy solution would be to remove the grout and replace it with caulk. But since the glass tiles have cracked and you have the visible bulge, that indicates movement. And movement usually indicates water intrusion and saturated and swelling wood within the curb.

With a saturated curb, I'll usually recommend investigating by removing tile from the outside vertical portion of the curb. That allows a curb inspection without touching the shower tile or the shower membrane.

With your shower being a sunken shower, without removing any of the glass all you could do is open the shower door and pop off the bathroom floor tiles that go right up to the edge of the curb. You need to see how the membrane is detailed.

Once you see the membrane, you can usually fold it back a bit to access the wood underneath. Excess moisture may be obvious, or you may need a pin moisture meter to measure.

The basic goal is to discover if the membrane was properly installed? If it was, how has it been compromised? If you find fault with that limited inspection, then you'd have to pull the glass and do the same to the remainder to that floor tile/curb intersection.

Then you repair and rebuild.

It won't be easy and it won't be fun. Compromised curbs are indeed the proverbial can of worms. Sometimes you can open it up, let it dry, make a simple repair, re-tile, and be done with it. Other times it leads to more and more digging and a full replacement of the shower pan.

Hi guys, more information and pictures for you. The house is in Florida, built in the 1960's...the bathroom is built out with wood studs I think.

Address a few issues:

The blue glass tiles inside of the curb are not cracked or damaged. The only damage I believe is from the connection of the water getting behind the tile and the cracking of the tile. To be more specific, I am referring to the picture closeup of the white bathroom floor tile that right before the edge of the curb that cracked. I do not think this was from excessive force of me standing there or dropping anything. To be specific, this is how I think it happened. If you look at the interior of the curb you will see the top is the edge of the white bathroom floor tile, and in between the bathroom floor tile and the top of the interior blue glass tile, there is caulking I have in there to prevent water from getting in between the white bathroom floor tile edge and the top of the blue tile (the gap between the two). At first there was no caulking, just grout, which in a few months completely cracked and I did not notice it, so water was getting between the gap and under the bathroom floor tile. I think this water might have put upward pressure on the floor tile to make it crack, as the tile right next to it also looked like water got under it and made the grouting split. The crack in the bathroom floor tile when I touched it was moist, so I think it was from the water. Keep in mind the bathroom floor tile does not get splashed from the shower, as its on the otherside of the shower floor glass.

It is very possible that the bulge was there from day 1 and if I had to guess I would say it was..I just think it was a poor job. I do not know for sure, but it seems to me like the curb was built out of cement and not wood. I think he just laid the bathroom floor tile an inch or two past the cement curb frame, then put on thinset and laid the tile in the interior of the curb hoping that it would line up, but it clearly wasn't doing right. However, I have attached some pictures that may help a little bit, but maybe not so much.

I am tight in cash right now, so I do not think I can afford any signficant work on this issue right now, but I would like to know everyone's thoughts on how to take care of this the right way for the near future when I have better cash flow.

In the meantime, if I chip out all of the cracking grout from the bottom of the inside curb tile, and fill it in with silicone will I be okay for now and prevent any more damage/water damage (the top gap on the inside curb I already chipped out and siliconed a few months ago and is holding up)

I might have misread your third photo. It looks like what I took to be a crack in the grout and tile might be a wayward strand of hair. lol

The thing to remember is that when you really pick things apart in proper shower construction is that caulk, tile, and grout are really not part of the true waterproofing system in a shower. They shed water. They make the shower look pretty to the eye.

The membrane beneath the tile is the actual waterproofing.

It certainly is possible that different methods were used in constructing your shower. If you are looking for a band-aid fix, then sure, recaulking can help by eliminating water penetration. Or if your shower is improperly constructed, or if the caulking is done wrong, it can hurt by sealing moisture in.

Cracked grout indicates movement within that grout joint. The reason the joint can have movement can be due to one of several things.

But for a band-aid fix, wherever you see cracked grout, remove the grout in that joint. If there is moisture behind the cracked grout, try to allow it to dry out. Then you can caulk.