Flooring Tile - loose tile and cracking grout

Unfortunatley we have had nothing but problems with our 13" ceramic floor tile since it was installed in June '02. After the tile was originally grouted, probably a week or so later it looked like some grout lines did not have enough grout and others, while not cracked did not look quite right. The installer came out and lightly grouted over this area. Then I noticed that some of the tiles seemed to have corners that were not level. If you walked barefoot on the floor it was noticeable in that your toes would kick the corners that protuded. He came out again, broke three floor tiles (I had to purchase an additonal case of tile) in an attempt to rectify the protruding corners. We have a pocket door that leads from the kitchen (room that he tiled) into an entry hall.
There was a height issued due to the pocket door needing to open and close. He had to make some type of adjustment, now that I think about it, in the threshold area but I'm not exactly sure what it was. in additon to the subfloor preparation, since we had dead space between the top layer of plywood and the joists that were covered by 1x6's that had 1/4" stringers in between them. This general area was one of the areas he grouted over after the initial floor install, then he had to come back out again due to cracking whereupon he broke out two floor tiles an screwed in at least 8 crews.

Since the joists are 16" apart, 5/8" plywood was used and rather than cement board the installer glued and screwed 1/2" "Dense-Shield" to the plywood. In the other area of the kitchen that he regrouted, two grout lines appear almost chipped out looking but the tile doen not move that I can tell. He does not know how to resolve the problem. Does anyone have a solution? My son suggested breaking out the remainder of the craced grout in these areas and squeezing in a glue by Elmer's called ProBond,
then regrouting. The last time I spoke with the installer he suggested removing the floor tile and the DenseShield and replace with cement board in the area where the one tile moves.
This seems insane to me. It seems to be making more of a problem to have two different substrates.

I am at wits end with trying to find a solution. Thanks for any help anyone may give.

I spoke with him a week and a half ago and he stated that he had attended a seminar and hoped he would find a solution.

Not sure if you know the answers, but a few questions for you.

1. Did the installer use a latex modified thinset mortar cement to bond the tiles, or did he use a mastic cement? The former must be mixed on-site from a dry powder and water. The later comes in a bucket ready to spread.

2. I am a little confused about your floor construction. You said your joists are 16 inches on center. How long are they (from end to end), Are they supported by any beams between the ends, and if so, how far from each end? What are the dimensions of the joists (i.e., 2x8; 2x10 etc)?

3. Regarding the floor construction aboove the joists, you said "in additon to the subfloor preparation (a layer of 5/8 plywood followed by denis-shield), since we had dead space between the top layer of plywood and the joists that were covered by 1x6's that had 1/4" stringers in between them." I don't understand this. Does this mean the sub floor over the joists are 1x6 boards? What is the "dead space"?

Thanks for the reply Brewbeer. Sorry I did not make myself clear in my description of the subfloor. The "dead space" that I referred to is no longer an issue since the stringers that were between the 1x6" floorboards and the plywood above were removed and the plywood was screwed into the 1x6" boards.
Our house is a raised ranch and, apparently 50 years ago when it was built, many were constructed in this manner to accommodate for the installation of hardwood floors. (something to do with expansion and contraction of the wood and allowing air to flow beneath the floorboards. We are in the Midwest. All of our floors are hardwood with the exception of the kitchen and bathroom.

This is the existing subfloor: 2x10" joists that are 9' from end to end that are not supported by any beams. The joists are covered by 1" thick x 6" wide boards over which either a 1/2" or 5/8" plywood (not positive of the thickness, since there is no way to see when I look up at the floor from the laundry room in my basement I can only see the 1x6" boards) was screwed into the 1x6" boards. The plywood was covered by 4'x4' wide and 1/4" thick sheets of Dense-Shield which were glued and screwed down to the plywood. (The Dense-Shield was recommended by the installer. It is easier to cut, is lighter than cement board and has a built in vapor barrier is mold and mildew resistant and has no paper to delaminate when exposed to water.)
The installer claims he followed the specifications of the mfr. upon installation, but says he cannot figure out why the grout is cracking and the floor is loose. I don't think I will be hearing from him again since his attitude seems to be since he doesn't know how to resolve the situation what do I expect him to do? Quite honestly, I don't know what the solution is but I paid him $850.00 for installation and I'm afraid that I will have to have the floor retiled. Then I will not only be out the installation but also the price of my tile and supplies. Any advice from you or anyone else is greatly appreciated.

Interesting...I didn't know Densheild came in 4x4 sheets, or in a 1/4 inch thickness. I don't like the stuff..especially on floors(but that just my opinion) It does sound like you have some movement. The span of 9 ft is ok..and the double thickness of wood before the denshield is ok too.
But with the protruding corners you mentioned, I wondering if it was just a bad installation. Does the installer have a lot of experience? Did he use modified thin set under the denshield and to install the tile on it? I don't know what else to suggest...but if he wants to come back and fix it, you should let him..but it shouldn't cost you anything, since it's been loose since day one. It would at least be interesting to see what's under the loose area.:confused:

i'm not a big fan of dens-sheild all it is is glorified drywall and drywall is not suitable for underlayment for an installation of tile on the floor especially 1/4 inch.Sounds like you should have plenty of sub-floor with the 1/2 or 5/8's ply even with the 1x's being gapped the ply should be eneough to support the floor.Is the tile sticking good to the floor? any chipped?any broken?See if you can pop one up.easy? hard?is there alot of mortar stuck to the tile?Does part of the dens-sheild come with it?What size notch did he use?There are an awful lot of q's to be considered before anyone can say anything with any accuracy as to what the problem is.Stay after this guy and make him fix it even if it means tearing it out and starting over.If he tears it out to be safe add another layer of ply like 3/8 and use durock instead screwed and glued i'm afraid though there is no easy fix for this problem see if you can do the things i've described and get back to us and let us know what you find:cool:

Thanks for your input, adanac and floorman. I have another installer coming out next week for his opinion and will definitely post his thoughts.