Civil Engineering Reference
In-Depth Information
Chapter 2.6
Earth, clay and chalk
Well over half the world's
population live in dwellings built
from subsoils of varying types and
using a variety of methods. Earth or
mud was widely used in the British
Isles, both in load bearing form as
mass walls and as infill for timber
framed walls (Figure 2.63). The latter
category is also mentioned in
Chapters 3.3 and 9.2.
There is much interest in the
maintenance and repair of earth
walled buildings and there is an
increasing wealth of publications on
the subject. The topic was one of the
first to be examined by the Building
Research Station and Special
Report 5 was published in 1922
(129)
.
A building constructed from
stabilised soil blocks existed for
many years on the BRE natural
exposure site, and was still in good
condition when demolished.
There are distinctive techniques
for construction dependent both on
the characteristics of the locally
available subsoils and local
traditions.
●
Cob, cleam, clob or clom - these
walls are built of subsoil with a
high clay content, mixed with
straw and water (Figure 2.64),
placed in situ on a stone plinth
about 600 mm wide, heavily
trodden down, and then pared back
to an even line. Large numbers
were built in the West Country up
to about the end of the nineteenth
century; some survive from the
1600s. Particularly good subsoil is
found between Oxford and
Aylesbury and is known locally as
'whitchert', meaning 'white mud'.
Chalk cob is common in
Hampshire, Dorset and as far north
as Andover. Where chalk is the
main constituent, slimmer walls
are produced . Boundary walls
around 300 mm thickness to a
height of over 3 m have survived
for well over 100 years
HU
Figure 2.63
Locations in Great Britain and
Northern Ireland where earth
buildings are situated
NB
NJ NK
Inverness
Aberdeen
NU
Edinburgh
IC
Newcastle
Clay-lump (in Spanish: adobe) -
mud bricks are formed from clayey
subsoil mixed with chopped straw
in a mould and then air dried.
These walls are
laid using a mortar of earth or
clay. Buildings are found on the
chalky boulder clays of Norfolk
and Suffolk where the method was
reintroduced from the Continent
around the end of the eighteenth
century, having formerly been
used on a small scale in Roman
times
Belfast
●
SC SE
York
Liverpool
SH
TG
TM
Birmingham
Swansea
Brighton
TV
SW
Plymouth
