by Athena and Bill Steen - Cohabitat

Obviously the construction of an upper-story floor in terms of the
actual construction and the calculation of loads, etc. is more complicated
them can be dealt with in a small booklet like this, but we have included
short descriptions of the basic techniques to give the reader some idea of
how these infill sections are constructed. The relationship between the load
of the light clay/straw to the joists and walls as well as the technique for
constructing the in fill, needs to be thoroughly understood before attempting
this type of construction.
Light clay/straw infill
A mixture of light clay/straw can be tamped directly into place,
using a slip-form attached to the bottom of the joists or rafters thus
producing a flat surface when the form work is removed The
reinforcement rods, placed every 2-4 inches, rest on the ledgers which
are attached to the lower sides of the joists.
These infill sections can also be curved by using a form work
of flexible branches such as willow which are bent to the desired arc
and placed 1 or 2 inches apart The light clay/straw is then packed on
top of them.
Prefabricated blocks of straw/light-clay
T-shaped straw/light-clay blocks can be prefabricated to rest
between the rafters or floor joists. Two reinforcing rods are worked
into the middle of the block when packing the wet mix into the form.
The blocks can be removed immediately from the form and set aside
to dry. A little clay slip can be used between the blocks as mortar,
when the dried blocks are laid in place. The blocks can be shaped to
produce either a flat or vaulted ceiling.
Light clay/straw ceiling rolls
Another version of creating a flat infill section, is to use reels
made up of a fibrous material, like straw or grass, coated with clay
slip and then wrapped around reinforcing rods. These reels are slid
between the joists, compactly against each other while still wet. As
with the other infill methods, the bottom of the rolls can then be
plastered.