When i texture the floor the ceiling texture takes on the floor texture too, is it possible to define separate textures for the floor and ceiling?

Yes it is. To do this double-left click on the floor space of a room in 2D construction mode.
From the room textures dialog select the Texture button
This will bring up a Floor and ceiling parameters dialog
Notice you have a Floor and ceiling tab, use the Texture: drop down menu to select a texture for the floor/ceiling.

Click Ok