The Rural Voice, 2019-03, Page 69 Wood has been a primary
construction material for centuries.
While it continues to be used
commonly in conventional stick
frame construction, there has been a
trend towards use of other materials
such as steel and concrete in many
applications. According to two
speakers at the recent annual
conference of Forests Ontario there’s
good reason now to consider wood
instead of (or along with) concrete
and steel for many construction
projects, including multi-storey and
commercial buildings, or even small
bridges.
John Pineau, the Provincial
Leader of FPInnovations in Ontario
talked about a bridge recently built at
the Petawawa Research Forest north
of Ottawa. The intent of the bridge is
to demonstrate wood construction as
an alternative to other materials for
use in forest access roads or even by
municipalities. Pineau first talked
about the much lower carbon
footprint of wood compared to other
materials. In fact, use of wood
actually creates a net sequestration of
carbon, while other materials such as
steel and concrete may cause a net
release of carbon into the
atmosphere. He used the example of
a cubic metre of wood (which is
roughly equivalent to 118 - 2 x 4s, 8
feet long). In production of the wood,
trees actually sequester 780 kg of
Carbon Dioxide (CO2). For that
cubic metre of wood there is CO2
released to the atmosphere through
harvest of the trees (10 kg), hauling
(7 kg) and milling (32 kg). That
results in a net sequestration of 731
kg of CO2 per cubic metre, as long
as the wood remains in use in
whatever is built.
Pineau says the wooden bridge
(constructed of prefabricated,
engineered wood components) is
comparable in both cost and expected
life span to an equivalent steel
bridge. At roughly 43 feet long and
16 feet wide it meets all standards
required and will handle fully loaded
logging trucks or heavy military
equipment. In addition, the
construction and installation process
was completed more quickly and at
lower cost than for a comparable
steel bridge.
David Moses, Principal of Moses
Structural Engineers, says he sees a
shift in building techniques towards
greater use of wood, with potential
positive environmental impacts. One
reason he sees for this happening is
the advances in engineered wood
products that have happened over the
past 40 years. He listed a number of
advances, including: nailed laminated
decking, improved connectors for
timbers, improved machining and
CNC techniques, improved adhesives
and techniques in manufacturing
glue- laminated timbers,
development of LVL (laminated
veneer lumber), timberstrand
products and production of cross-
laminated timbers.
Also contributing to the trend is
recognition of these advanced
products and improved wood
construction techniques in building
codes. For example, the Ontario
Building Code was amended in 2012
to allow for construction of wood
buildings up to six storeys high. This
is humorous in some ways as there
are several seven or eight storey
wooden buildings in Toronto that are
100 years old. There are much higher
recently built wooden buildings
elsewhere, including one 13 stories
high in Quebec City and the 18-
storey Brock Commons building in
BC, with other, even higher buildings
being planned at various locations.
Moses says much of the efforts to
reduce carbon emissions from
buildings has focused on reducing
energy use for heating and cooling.
He says there is also large potential
for reducing carbon emissions
through use of construction materials
March 2019 65
Wood is a strong
and carbon-
positive building
material
Steve Bowers
is a forester,
forest owner
and member of
the Ontario
Woodlot Assoc.
Woodlots
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