Floor Sloped: Settling or Built that way?

[Rhadley]

I am getting ready to re-tile a 2nd story bathroom. The existing tiled floor is flat for awhile and then slopes down 1" in 4 feet. No tiles are cracked, and the lowered tiles end up even with the carpet that butts up to them at the doorway. The first story floor is similarly sloped below this floor.

We have had an extremely dry year in Houston and that makes the soil shrink. If this is due to settling, I am concerned about installing the tile and later having the floor raise back up and crack the tile. (Old tiles are 4" square)

1. Should I slope the floor as it is right now, assuming the old tiled floor has always sloped since the tiles are not cracked?
2. Should I level the floor and deal with the 1" step at the carpet?
3. Should I wait until we get rain and the soil goes back to its normal water saturation level?

 

[Rhadley]

I examined the cabinet along the tiled floor and noticed that it has no gaps with the tile, and the top is flat, so that means the floor was built with the slope. Otherwise I would see a separation between cabinet and tiles.

If I do that with larger tiles, it seems like the tiles would look noticeably tipped and the edges raised. Any comments on whether I should tile it sloped or try to make the whole floor level? I would get a step down to the carpet if I do.