Building with earth - Gernot MINKE (1)

Lime
Sand
Fat-free
cheese
Linseed
oil
Clayey
loam
Trasslime
Cowdung
µ-value
Application
Before applying the plaster, the loam sur-
Structural methods
1
–
1
1
–
1
–
–
3
3
6
15
–
–
0.5
0.5
–
–
–
–
–
–
–
3
–
–
–
–
11.2
10.8
6.2
9.7
face should be moistened and primed with
lime-casein milk. The plaster is then applied
in two layers, bringing the total thickness up
to a maximum of 20 mm. In the first layer,
some cement can be added for faster cur-
Protection from rain
One method of preventing rain from coming
into contact with a loam wall is to provide
it with a roof overhang. A sufficiently
high plinth (30 to 50 cm) can protect from
1
–
3
–
0.05
–
–
15.2
ing. The second layer should be applied
splashing rain. The joint of the wall with the
1
–
3
0.25
0.05
–
–
28.5
while the first is still slightly moist. When
plinth has to be carefully designed so that
1.5
12.6
–
10
–
–
2
6
8.0
shrinkage cracks occur, these should be
moistened with a brush dipped in lime milk
and then closed by rubbing with a trowel.
the rainwater can flow down unhindered
without entering the joint between wall and
plinth. In 12.8, solution A is unacceptable.
It should be noted that lime plasters cure
Solutions B and C may be acceptable in
12.8
when in contact with carbon dioxide from
the air, and this process is only possible in
areas with little rain. Solution D is common,
whereas E and F show perfect designs for
the presence of sufficient moisture. There-
combating this problem.
fore, walls should be sheltered from direct
sun and wind, or kept moist with a damp
Protection against rising damp
fabric.
Exterior loam walls have to be protected
Internal plasters can be applied in one layer.
from rising damp in the same way as baked
Gypsum plaster or gypsum-lime plaster,
brick or stone masonry walls. A damp-proof
with or without casein, can also be used in
course, usually bituminous felt, and some-
internal work. Cement plasters, however,
times plastic or metallic sheets are used.
should not be used even for internal work.
As these means are fairly expensive in the
developing world, a 3 to 4-cm-thick rich
Effect on vapour diffusion
cement concrete layer is often used as an
The effect of adding double-boiled linseed
alternative. This should be impregnated
oil and casein on reducing the vapour diffu-
with bitumen or waste mobil oil.
sion of lime plasters was tested at the BRL.
The values of the vapour diffusion resistance
Protection against flooding
coefficient µ obtained are listed in table
In kitchens and bathrooms, the plinth should
12.6.
have a waterproof skirting of tiles, slates,
rich cement plaster etc. The skirting design
Shingles, planks and other covers
should prevent water from leaking or broken
pipes, which could flood floors, from
reaching the loam wall.
Besides plasters and coatings, shingles,
planks, larger covering panels or baked brick
walls separated by an air cavity can be used
to protect loam walls. These methods are
especially useful if additional thermal insulation
is to be applied from the outside.
A common method is shown in 12.7. In
Mesopotamia (Iraq), layers of glazed baked
bricks have sheltered adobe walls for thousands
of years. It is always advisable to
separate such covering layers from the wall
with an air cavity, so that rain that penetrates
can drain out and does not harm the
wall.
103
Weather protection