by Athena and Bill Steen - Cohabitat

As guides or reference points while troweling the earthen
mixture! sections of re-bar or pieces of wood (the same dimension as
the depth of the application) laid at periodic intervals across the base
layer. For example, if each layer is one half inch thick, a piece of #4
re-bar can be used as a guide to regulate depth. As each section of
floor is completed, the re-bar or wooden guides can be removed and
repositioned for the next section. Make sure to carefully fill the gaps
left after removing the guides.
When a room is large, it can be difficult to maintain a level surface
when installing the floor. One remedy is to use pre-laid, 3 4" strips
of floor mix at approximately 6 1
intervals, to create reference points
for the correct height of the floor. Once in place they can also be used
to lay a board or level across and adjust the height of the floor.
The first layer of earthen mix can be left slightly rough so that
the second layer will better adhere to it. There is a point when the
floor will be dry enough to walk across -yet still damp enough to be
workable. At this time, any cracks or shrinkage lines that have
occurred, can be worked with a trowel. This first layer can be left
fairly rough for the next layer to adhere to. To help spread the
concentrated loads of feet and knees, so that no marks or depressions
will be left on the floor surface, two pieces of plywood or some other
flat, rigid material can be alternately leap-froged across to create a
path of movement.