Building with Earth: Design and Technology of a Sustainable Architecture

Labour input

The labour input in traditional rammed earth
walls constructed manually, including pre-
paration, transportation and construction, is
from 20 to 30 h/m^3. By refining the form-
work system and using the electrical vibra-
tor described on p. 55 of this chapter (see
5 .12), labour input is reduced to 10 h/m^3.
With the highly mechanised techniques
explained above (see p. 56), in which trans-
portation and filling is done by a dumper
and compacted by heavy pneumatic rams,
labour input can be reduced to as little as 2
h/m^3 , which is only 10% of the labour used
with traditional techniques, and significantly
less than that needed for masonry work.

Thermal insulation

The thermal insulation capacities of solid
rammed earth walls using normal soil is not
sufficient to provide the levels of thermal
insulation required in cold climates. The
U-value of a 30-cm-thick rammed earth
wall is as much as 1.9 to 2.0 W/m^2 K. To
achieve a U-value of 0.5 W/m^2 K, necessary
in many European countries, a thickness
of 1.6 to 1.8 m would be required. In cold
climates, therefore, either a thick wall of
lightweight loam or additional conventional
thermal insulation should be used.
Some potential methods for making loam
walls with improved thermal insulations are
described in chapter 14, p. 108.

Surface treatment

A rammed earth wall requires less labour
and material inputs for surface treatment
compared to walls made using other earth
construction techniques. As a rule, it is
neither necessary nor advisable to plaster
a rammed earth wall. If the surface is
sponged with a moist felt trowel immedi-
ately after dismantling the formwork,
then a smooth surface is easily produced,
one that may be painted or wallpapered

(in cases involving interior wall surfaces). If

exterior surfaces thus treated are sheltered

from rain by roof overhangs and against

splashing by a plinth, a coating of paint is

sufficient to protect them against the ele-

ments. Care should be taken that coatings

neither peel nor crack.

60 Rammed earthworks

5.31Rammed earth

test structure, Univer-

sity of Kassel

5.32 to 5.33Con-

structing the rammed

earth dome with a

rotating formwork

5.32

5.33

5.31