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STRUCTURE & FABR I C :
ME TAL ,
WOOD & GLASS
ARCHITECTURAL TIMBER
HISTORY AND CONSERVATION
JOSEPH BISPHAM
T
HE USE
of European oak and exotic
hardwoods as structural and decorative
building materials has recently become
very popular. Softwood timber, on the other
hand, is widely used for cladding, but otherwise
its significance as a traditional construction
material has been widely overlooked in this
timber revival.
The use of softwood as a building material
has a long tradition. Historically, imported
softwood species such as
Pinus Sylvestris
(Scots pine, also known as redwood or Baltic
pine) were recognised as durable building
materials which were easily worked. With its
close vertical grain, softwood made a perfect
material for the detailing and paint finishes
of the 18th century. Despite the name, many
softwoods are also both hard and strong, and
are suitable for complex structural use. (The
term defines wood from coniferous trees, not
soft wood. Indeed hardwoods such as balsa and
willow are not hard at all.)
OAK’S GOLDEN AGE
Various timber species were used for
construction in medieval England. Oak,
elm, sweet chestnut, poplar and the many
varieties of fruitwood appear in building
accounts from the reign of Henry III. Oak
has survived in our medieval buildings to
a greater extent than any other timber. It
was, and remains, the most popular native
hardwood used for the construction of
timber frame buildings in England.
The medieval carpenter was able to source
construction timber from pollarded trees and
from coppicing in locally managed woodland.
Coppiced trees are cut down close to the
ground leaving the ‘stool’ and they regenerate
from shoots that continue to grow from the
sides of the stool until they are large enough
to be used as timber. In contrast, pollarding
involves cutting the tree off at 2–3 metres
above ground, protecting the new shoots from
grazing animals.
Coppicing would be carried out in an area
of ‘underwood’, a lower ‘storey’ of managed
trees beneath taller, more widely spaced
‘standards’ that were allowed to grow to
maturity. A managed height of approximately
4.5 metres could be worked as an underwood,
so every 10–20 years the underwood would be
cut to the ground, after which the woodland
would produce new growth yielding fresh
harvests of wood poles.
High value trees such as oaks would be
selected to grow through the underwood
canopy to mature. These trees would develop
straight boles (the main part of the trunk before
it divides into branches) with fewer branches
lower down the trunk and with the crowns
much higher. Once felled and converted, these
would have been used for the longer sections
of timber needed in the construction of timber
frame buildings, barns and hall houses. They
would also have been of greater monetary value
than the unrestricted growth of timber from
the field oak.
The history of coppice work has been
well recorded since the 12th century, and it is
known that pollarding and coppicing gave a
regular crop of wood and timber for domestic
and building purposes. This type of woodland
management and regeneration remained
common practice until around 150 years ago.
The widespread use of oak as a
construction timber in the past suggests
that our ancestors were well aware that oak
Section of an oak beam from Lincoln Cathedral: dendrochronology indicates that the oak was felled in the first quarter of the 13th century. The well-spaced growth rings
are typical of faster grown timber from managed woodland.