Building with Earth: Design and Technology of a Sustainable Architecture

Bamboo-reinforced rammed earth walls

Hard-wearing floor surfaces need to meet
very high standards. They must resist pres-
sure abrasion, be waterproof and show no
cracks. It is very difficult to build such sur-
faces from loam, but if carefully done, it is
not impossible. The most difficult criterion
is to achieve sufficient strength against abra-
sion or surface hardness (see chapter 2,
p. 34). It is often easier to avoid the effort
involved in achieving this by using brick,
timber or stone floor tiles over the loam,
or by covering the loam with a carpet, rug,
fabric etc.

Traditional earth floorings
Illustration 14 .15shows Niemeyer’s version
of a traditional loam floor (Niemeyer, 1946).
The base layer consists of loam, about
15 cm thick, with high clay content. This
acts as a water barrier, and is applied in two
layers that are compacted by beating or
ramming until no cracks appear while dry-
ing. The next layer consists of coarse gravel,
which interrupts capillary action. Above this,
a 10-cm-thick layer of straw loam provides
thermal insulation. An additional 4-cm-thick
layer of straw loam, stabilised with cement
in the proportion 1:6 (1 part cement : 6 parts
straw loam), is added so that heavy loads
can be carried. As the final layer, Niemeyer
recommends a 2-cm-thick layer of cement
mortar with sawdust. Two coats of water-
glass are then applied while the final layer
is still moist. Finally, after it is completely dry,
the surface is waxed.
The author of this study suggests reversing
the sequence of the bottom two layers.
To interrupt capillary action, coarse gravel
should be used as the lowest layer. Loam
with a high clay content should form the
next layer, acting as a water and vapour
barrier (damp-proof coarse). As described
below in this chapter, stabilised loam mortar
may be substituted for cement mortar. In
traditional German farmhouses and barns,
earth floors were built in a similar way, so
that even cars (without pneumatic tyres)
could drive over them. Instead of the

cement plaster surface, loam plaster that

contained loam with a high clay content

and large amounts of coarse sand and

fine gravel was used. This was applied in

a 7-cm-thick layer and compacted by beat-

ing. In order to harden the surface, it was

sprinkled with Fe 3 O 4 flakes (flakes produced

by forging glowing iron) and beaten into

the surface together with cow’s blood,

cow’s bile or tar.

Modern earth floorings

In 1984, the two different loam floors

shown in 14 .16were successfully tested at

the BRL. Design A has a surface, hard

enough to be walked on, that is divided by

a timber grid, while design B shows a loam

floor paved with timber blocks.

The subflooring is identical in both cases,

consisting of a 15-cm-thick capillary break-

ing layer of gravel, followed by a water and

vapour barrier of plastic or bituminous felt

paper, and topped with a 10-cm-thick layer

of expanded clay that acts as thermal insu-

lation.

The first layer of moist clayey loam is placed

on top of this subflooring and rammed

(14 .17and 14 .18). In both cases, a primary

grid of timber battens (10 x 10 cm) is laid

over this.

In design B (14 .16), this grid is then filled

with timber blocks laid with a loam mortar

stabilised with 6% to 8% (by volume) of

double-boiled linseed oil. The blocks are

placed so that the annular rings are exposed

(14.20).

In design A, a second layer of loam mortar

is applied and rammed, over which a

secondary grid of timber strips is laid. The

112 Designs of building elements

14 .15Traditional flooring

for living rooms (after

Niemeyer, 1946)

14 .16Modern earth floo-

rings (Minke, 2000)

14 .17 t o 14 .19Making

a rammed earth floor

14.20Making a rammed

earth floor with a wood

block cover

A B

14 .15

14 .16