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Construction of houses varies significantly between Europe
and North America. European houses are
typically built with masonry, while North American houses are usually made of
wood. Why is this so?
When North America was settled, the vast forests provided a
free resource of building material, so wood was the primary construction
material used. This still holds today:
compared to Europe, North America possesses large forests which are harvested
and used extensively as construction material.
After a few hundred years, a tradition of construction has developed and
persists, so that most contractors or builders know how to build a relatively
inexpensive home using wood as their primary construction material.
By contrast, most large forests in Europe were clear cut
several hundred years ago. These
original forests have never been allowed to return to their original state; the
population density of Europe simply does not allow it. By the law of supply and demand, wood prices
in Europe are significantly higher than they are in North America. There is also a tradition of construction in
Europe which involves masonry, and which goes back several hundred (even
thousands) of years. Most Europeans are
surprised when they visit North America and notice that the vast majority of
houses are built primarily of wood.
Similarly, most Americans visiting Europe are frequently surprised that
most European houses are not built with wood.
The implications of these different approaches to construction
have a particular relevance as we face the future and address the challenges
posed by changing climate. The
scientific community shares an overwhelming consensus that man-made CO2 is a
major contributing factor to our changing climate. A new awareness of the impact of our
activities on CO2 added to the atmosphere has put the practice of home
construction into sharper focus by many in the construction industry.
Research indicates that masonry construction is “greener”
than traditional wood construction, for several reasons. First, fewer trees are harvested, and more
forest remains intact. Trees are a major
carbon sequestering force in nature: they remove CO2 from the atmosphere and
create oxygen. Conversely, cement
production creates CO2, and the question must be answered: which has less impact
on the environment, wood construction or masonry?
As discussed in this article, for a 2,400 square foot wood
house, it takes approximately 750 cubic feet of wood to construct only the
walls of the house, and requires 2.3 acres to produce that amount of wood. This 2.3 acres of mature forest would
otherwise remove 11,818 lbs. of CO2 per year from the atmosphere (5,200
lbs/acre).
By comparison, a 2,400 square foot masonry house requires
23,558 lbs. of cement to construct only the walls. During the manufacture of
the required amount of cement, 11,779 lbs. of CO2 are released into the
atmosphere – resulting in slight improvement at the end of the first year.
However, concrete provides significant improvement from year 2 and beyond.
Another issue that is a factor is the area of disruption. Cement production is relatively localized to a
few square miles of quarries and mills, whereas lumbering affects thousands of
square miles of land and requires considerable energy be expended to clear and
transport a forest and convert trees in to lumber. Lumbering decreases the
biodiversity of forest; it creates erosion and pollution problems. It also
enters into the problem of forest fires. Instead of allowing forest fires to occur as a
natural function, forest managers prevent and put out fires, which robs the
soils of the benefits of natural fertilization that occurs during burning.
This comparison does not take into account other factors of
construction relating to sustainability, such as the fuel energy – even more if
the lumber is imported. A concrete house
has a much longer service life than a wood frame house, lessening landfill
burdens and creating the need to expend more energy to reconstruct the house.
Europeans have traditionally built homes that last far longer than homes built
in the U.S. The result is that with their reduced birthrates, the housing stock
turnover is far less. This translates to a much lower percentage of GNP devoted
to housing, 9% compared with over 12% in the U.S.
To build a 2,400 square foot house requires 2.3 acres of
mature forest which absorbs 11,818 lbs of CO2 per year. Producing the 23,558
lbs. of cement required to build the same house with concrete produces
virtually the same amount at 11,779 lbs. of CO2. The CO2 ‘payback’ when
building with concrete is one year. Considering
it takes 50 years for a new trees to mature, the ‘ROI’ from using concrete is
2,290% by the time the re-planted forest fully matures.
In addition to the environmental benefits provided by
concrete construction, significant savings in heating and cooling houses and
other buildings are realized through more thermally efficient concrete
construction. These homes will also last
much longer, have a higher resale value, will be able to withstand rot,
termites, fire, storms, etc., and thus have a much higher value over their lifetime
than wooden construction.
It is time for North America to reassess its construction
practices and evaluate which form is better: wood or concrete? Instead of imposing burdensome new government
regulation on the marketplace, we should educate the new homeowners of tomorrow,
and allow the lower cost of superior construction determine how homes of the
future are built. Wooden construction is
often called “stick construction,” it is not a compliment, and it is
accurate. Just ask the third little pig
or the big bad wolf.
