what did i do wrong that caused this

Hey "oh mike" thanks for the speedy responce,,, joists are 2 by 10 , close to 16 inchs apart, original 3/4 subfloor + sheeted with1/2 inch ply, thin set under 1/2 inch hardie backer board screwed down with hardie screws, a little history , about five to six feet away is our sliding glass door, which had a good amount of water damage, and we replace the sliding door and the water damaged ply which extended from the door into the room about 18 inchs, and while gutting that out noticed that the previous owner sistered the floor joists but only put the 2 by 10s in place next to the original, not fastened or anything, not sure if that means anything or not. Just wondering if all that may have been enough for everything under the tile to maybe settle, But anyway if i missed anything please let me know, i gotta figure this out, thanks again

hey Jazman, i just opened it up and seen how small the pics came out im going to try to redo that,The sections of subfloor i had to cut out , measured off wall 18 inches, and ran length of wall 7 or eight feet. And this section of tile where im having the isssues is about five to six feet away from this area i replaced. The original subfloor is 3/4 '' , so i put that same size back in, then resheeted the entire room with half inch ply, bringing total subfloor thickness to just under 1.25 inches thick. The ends are blocked, and the unsupported span length is about 8 feet. I think I covered the questions you had, let me know if i missed anything. Do you think if when i put that 1/2 ply down or the hardie backer down if any of those screws went into the "sistered" unfastened joists the previous owner put in , would be the culprit. You also asked about pics from underneath, i should be off work in about an hour and could take some pics from underneath if they would be helpfull, thanks guys

Do your best to describe the structure and exactly what you used to set the tile.

What is the unsupported length of the floor joists?

How thick is the sub floor?

What did you use for a tile backer?

Is there a layer of thinset under the backer?

What brand and type of thinset did you use to attach the tiles?

-----Has any thing odd happened to the house since the tile was installed? Flooded basement? High humidity?

To tell you what failed we need to know all of these things.---Mike---

Unsupported joist length: 7' roughly.
Subfloor thickness: 3/4 inch original ply + 1/2 inch ply= just under 1.25"
Tile backer: 1/2 inch thick hardie backer board, with hardie screws
Yes to having thinset under backer board as well
Used under backer board :MAPEI White Powder Polymer-Modified Mortar
only thing out of ordinary: finishing this room was held up, in the background of the pics used to be two sliding glass doors side by side, water damage from siding problems caused problems with post between the two doors and the ply subfloor ,about 9 inchs from door into room subfloor was softer than it should. Contractor framed in door opening of one door, replaced post and installed new sliding glass door.Then i proceeded to tear up the linoleum and found the water damage on the ply the contractor tried to cover up. so i measured and marked off the wall 18 inches out into room ,and 8 feet length wise and cut the subfloor out and replaced. Hey mike and others, after reading my posts i know i havent painted a clear enough picture and appreciatie you guys stayin with me on this one, any questions you got ,im glad to answer

Can't tell what this is supposed to be showing.
http://i509.photobucket.com/albums/s...IMAG0317-1.jpg,

This photo shows damage that may be a result of not having enough thinset under the tiles edge.
http://i509.photobucket.com/albums/s...AG0322-1-1.jpg

This photo looks like deflection in the substrate and again not enough thinset under the tile.
http://i509.photobucket.com/albums/s...AG0322-1-1.jpg

The photos are a big help but could be a little more helpful.

If everything was done as stated it all appears to be up to par and should be suitable for the installation.

Now there appears to be a problem with Photobucket, the photos don't work now but were fine three minutes ago. I may not have copied them correctly.