This information provided by Irulia Darkaith over at Stratics.
Ground level – or world height is counted as zero for the purposes of this discussion. (or 0 z where z is the vertical axis)
Foundation – is 5 tiles high or 5z
1st floor – 6z height of the first floor*
(you must raise a stone floor tile 20 times (i.e. 20 clicks of the decorator tool) to be level to the next floor)
2nd floor – 26z**
3rd floor – 46z
4th floor – 66z
“5th floor” – 74z/75z***
The curious thing about the 75z max height is that if you subtract 5 for the foundation you get 70 which Kryonix(?) referenced as the highest you could build – so maybe he meant you can go a max of 70 up from your foundation?
* this is based on the observation that a floor tile raised 5 times is the same height as short staircase (the kind you craft and the kind all houses use to enter a plot (customized or classic). The floor of any house is one tile higher than the staircase used to enter.
** this is based on counting the number of times I can raise a floor tile from the 1st floor until it’s level with the next floor.
***5th floor is defined as the highest spot you can effectively “build” upon, where build is defined as the placing of any manufactured stone wall/stair/floor. In other words if you have a floor that’s 74z high, you can add stone walls/floors, etc.). The term build does not seem apply to other items in the game. For example you can place a stone floor on the 5th level and then drop flowers, benches, chairs, etc without issue. but you cannot drop a stone wall. Yes you can raise floor tiles/gozas much higher but you can’t build on them and based on various accounts the floor tiles seem to go *poof* at server up; other objects (e.g. flowers, chests, banners, etc.) remain.
Interesting observation: if you are standing at 75z or higher and try to even take a stone floor/wall out of your pack you will immediately get the message “you may not build any higher”. Similarly if you try and trade an crafted stone wall/floor to another player while you are 75z or higher, you will get the same message. This may explain why grass tiles stored or locked down above 75z have vanished – they simply cannot exist at that height unless you “cheat” and raise them with the decorating tool.
Personal note: Height does vary according to where your castle/keep is located. Mine on Ice Island match this to a T. A person’s in a different location that I decorated had his first floor come up at 14 height.
Second note: You can use a sextant to determine how high your floors are.
Double click the sextant. You will get a reading that looks like this:
The digits after the last . is all you care about. It will tell you what height you are at. So my first floor height is 6 on the z axis.
It’s a great way to tell how high things need to be when raising floors to match other floors.