Building with earth - Gernot MINKE (1)

9.5 9.3
9.4
9.1 Traditional pit
house of the Pueblo
Indians, 3rd century
AD, (Bardou, Arzoumanian,
1978)
9.2 Variations of
wattle-and-daub technique
(after Vorhauer,
1979)
9.3 Traditional wattleand-daub
building,
Venezuela
9.4 Traditional wattleand-daub
technique,
Germany
9.5 Prefabricated
wattle-and-daub
system, Brazil
9.6 Spraying lightweight
loam
9.6
mixtures. The main problem with all of these
techniques has been the common occurrence
of shrinkage cracks.
The German architect Hans-Bernd Kraus
developed a technique in which a thin loam
mixture is sprayed simultaneously together
with dry sawdust (from a separate nozzle).
Both sprays intermix before hitting the wall.
Layers 4 to 6 cm thick are sprayed on
wood-wool slabs used as a lost formwork.
The wood-wool slabs also provide considerable
thermal insulation (9.6). Another sprayable
lightweight loam used for enhancing
the thermal insulation of walls is described
in chapter 11, p. 95.
Rolls and bottles of straw loam
In Germany and France, openings in the
frameworks of traditional timber-framed
houses are sometimes filled in with elements
formed by rolling straw loam around
a wooden batten, as seen in 9.7 and 9.8.
This is less labour-intensive then the wattleand-daub
technique, and has the added
advantage that hardly any shrinkage cracks
occur.
Two main systems are used: either a loam
dipped straw rope is wound helically around
a batten, or a straw mat pasted with loam
is rolled onto a batten. The labour inputs of
these techniques is still higher than those
using “loam strand” techniques (see chapter
8). A variation of the rolling technique was
successfully tested at the Building Research
Laboratory (BRL). It used a loam mortar
with a high coarse sand content, which was
pasted onto a metal or plastic wire mesh
(commonly used for reinforcing mortars).
The loam was pasted onto the mesh in
a thickness of 2 cm, and both were rolled
around a bamboo stick to form infill
elements (9.9, 9.10 and 9.11). Surprisingly,
shrinkage cracks nevertheless occurred
with this technique.
Illustration 9.12 depicts the traditional German
technique of building with “loam bottles.”
Here, secondary vertical members are
fixed 15 to 20 cm apart within the frame.
The “bottles” are made by taking 1.5-litre
masses of the mixture and dropping them
81
Wet loam infill