Building with Earth: Design and Technology of a Sustainable Architecture

mixtures. The main problem with all of these

techniques has been the common occur-

rence 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 consider-

able thermal insulation (9.6). Another spray-

able 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 ele-

ments formed by rolling straw loam around

a wooden batten, as seen in 9.7and 9.8.

This is less labour-intensive then the wattle-

and-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 .10and 9 .11). Surprisingly,

shrinkage cracks nevertheless occurred

with this technique.

Illustration 9 .12depicts the traditional Ger-

man technique of building with “loam bot-

tles.” 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

9.1Traditional pit
house of the Pueblo
Indians, 3rd century
AD, (Bardou, Arzou-
manian, 1978)
9.2Variations of
wattle-and-daub tech-
nique (after Vorhauer,
1979 )
9.3Traditional wattle-
and-daub building,
Venezuela
9.4Traditional wattle-
and-daub technique,
Germany
9.5Prefabricated
wattle-and-daub
system, Brazil
9.6Spraying light-
weight loam

9.5 9.3

9.4 9.6