grout in tiled shower base stays wet

I have a recently installed tile shower with a mud base. I was expecting the pitch of the base to be more drastic, or funnel-like. Mine is relatively flat, and although it doesn't drain exceptionally quick, the water does find it's way into the drain.

After my first shower, I squeegied the tile, and then towel dried everything. When I returned in the evening, I noticed that the grout in the tile surrounding the drain (approx. 3 inches or so on each side) was still wet. The rest of the grout in the tile base was completely dry. I kept an eye on it, and didn't shower in it again. It took about 5 days for it to dry out!

The company I contracted with to design/install the bathroom sent out a tile guy to rip up the tile surrounding the drain (the 3 inches on each side), lower the drain slightly, and then retile. I waited patiently for it to cure, sealed the grout twice, and then took another shower.

I went through my ritual of towel drying the tile, and when I returned at night, the grout in the tile that was previously holding moisture was now dry, but the tile immediately to the left and to the right, all the way to the ends of the base were now holding water. (if you can visualize a stripe of tiles, about 6 inches wide on either side of the drain, all the way across the base)

I find it strange that the tiles surrounding the drain are now drying out quickly, but that the area to the left and right are now holding water. I let it go for 4 days, and it finally dried out.

I think there is something wrong with the way the base was created because it doesn't seem right to have some of the tile grout stay perpetually wet. I would think this will lead to future problems, i.e. mold, tiles heaving, etc. The contracter is telling me this is normal.

Does anyone have any suggestions? Shouldn't a mud base have a fairly drastic pitch to it? Why is the replaced tile/grout around the drain now dry, but the adjacent tile now wet?

I'm not sure what to do at this point.

The entire floor should slope a minimum of 1/4" per foot to the drain. If the shower isn't square, take the longest distance from the drain to a wall, and you should have that amount of drop from the shorter wall, too (so it will be steeper). So, from any wall, it needs to be at least 1/4"/foot.

When they built the pan, did they put the membrane flat on the floor? My guess is that they did. When they redid the tile around the drain, they probably used all thinset, which is denser than deck mud, and not porous, so the water that pools is now held even further from the drain. It probably plugged the weep holes, too, preventing any of that moisture from eventually draining, and requiring it to evaporate instead. Tile and grout is not fully waterproof, a little bit will get under the tile with each shower. It should hit the sloped membrane and slowly flow to the weep holes in the drain. If the membrane is flat, or if the weep holes are plugged, it will build up with frequent showers.

This is one reason why the Kerdi system from www.schluter.com has so many advantages...the waterproofing layer is directly under the tile, so there is little volume of stuff to get wet. The conventional method still works fine, though, just not as well IMHO.

I'd check out www.johnbridge.com for some other opinions.