6.9). Both of these buildings are of the fourth
century CE. They each consisted of a high
central nave flanked by lower aisles. The naves,
which were each approximately 24 m wide,
were roofed in timber by truss-and-purlin
systems and the flanking aisles by lean-to
structures, also of timber. The use of tied
trusses over the naves eliminated side thrust
at wallhead level and enabled the builders to
adopt very slender walls. The buildings were of
light and delicate appearance, as is well illus-
trated by the seventeenth-century drawing of
St Paul's Outside the Walls by Piranesi (Fig.
6.8).
The importance of the timber-roofed basilica
was that it was a building with a relatively
large interior which did not have the massive
buttressing walls which were required to
support a masonry vault (the only other way of
achieving a large span at the time). It was an
early example of a building type which would
make a very significant contribution to the
development of Western architecture - the
large building with large interior spaces and
thin walls. It was the development of the
technology of the timber truss, from the
Roman period onward, which made this possi-
ble.
Examples of this type of building can be
found in all subsequent periods of western
architecture. The palaces and large houses of
the Italian Renaissance, the country houses
and public buildings of the classical period in
Britain, Northern Europe and America (Fig.
6.10) and churches from all subsequent
periods have structural armatures of this type.
In most of these buildings the timber struc-
tures which spanned the large interior spaces
were entirely hidden from view and made no
obvious contribution to the architecture. The
forms of the buildings would have been impos-
sible to achieve, however, without the technol-
ogy of the timber truss.
In the nineteenth century timber gave way to
iron and then to steel as the principal material
from which large trusses for long-span roofs
were constructed. The tradition of using large
timber trusses did not die out, however.
Twentieth-century examples have frequently
Fig. 6.10 Banqueting House, London, 1619-22. Inigo
Jones, architect. The roof trusses which span the width of
the Banqueting House in London (17m approx.) are
typical of the structural arrangements which were used to
create large interior spaces in the buildings of the
European Renaissance.been exposed in the interior of buildings and
used as part of the architectural language.6.2.3 Timber loadbearing-wall structures
A timber loadbearing-wall structure is a post-
and-beam arrangement in which both the verti-
cal and the horizontal structural elements are
of timber. The horizontal structures are similar
to those which are used in conjunction with
masonry and are beamed floors or rafter or
trussed roofs. In timber loadbearing-wall struc-
tures the vertical elements are also of timber
and consist of loadbearing walls formed by
closely spaced timber sub-elements tied
horizontally at regular intervals by further
timber sub-elements. The building type has
existed from the beginning of the Western
architectural tradition and has taken two
distinct forms - the half-timbered building and
the timber wallframe building.
The origins of the half-timbered building lie
in prehistory but the building type did not
become significant architecturally until the
eleventh century. It remained so until the
seventeenth century. In the half-timbered
building the walls consist of large timber
elements, frequently roughly hewn and with
cross-sections which were more-or-less square,
tied at each storey level by horizontal elements
of similar dimensions (Fig. 6.11). A third set of
elements, inclined to the vertical at between
45° and 60°, was provided to brace the
structure. The joints between the elements
(Fig. 6.12) were of the type which required the 185Timber structures