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Shopping Around For the Best Wood |
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| By Jim Cooper |
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A sure way to liven
a gathering of log home enthusiasts or builder-dealers is to
pronounce the superiority or inferiority of a particular species
of wood. It's like tossing a gauntlet into a gathering of
knights. You're almost guaranteed that someone will rise to your
challenge. Wood species provokes probably more heated discussion
than any other aspect of log homes.
Log home shoppers often come to me with glazed looks pleading
for help deciphering the mountains of fact, fiction and fantasy
around wood species. Often they think they can spare themselves
confusion by asking "Which is the best wood for a log
home?" Actually, that's when things get complicated.
Recently, I spoke with two log home company presidents who offer
logs made from the same premium wood species. One was aggravated
that some people in the log home industry failed to acknowledge
the superiority of his product. The other, who offered the same
species called it "vastly overrated." If industry
experts can't agree, how can a log home shopper possibly hope
for a definitive answer? Is there a definitive answer?
The difficulty of answering the question starts with the
question itself: "Which wood is best?" Well, what
exactly do we mean by best? Is it the strongest wood? The one
with the highest R-value? The greatest thermal mass? The most
decay resistance? The greatest insect resistance? The least
expensive? The one that shows the least shrinkage or the least
checking or warping? And what about beauty? Most home owners
plan to look at those log walls for a long time, so appearance
is no small factor. Each of these criteria really represents an
independent question and plays an important role in determining
which wood is "best."
Take strength for example. It's easy to examine a table
comparing the strengths of various woods and pick the superior
one. But is that the best wood? Only if strength is the sole
criterion. But log home shoppers usually have more than one
characteristic in mind when they ask which wood is best. To
further complicate the issue, shoppers don't always agree on
which characteristics should be considered and don't assign the
same priority to the characteristics they list.
Consider another characteristic: R-value. Again, it's easy to
find the wood species with the highest R-value by looking at a
chart. If R-value is our only interest in choosing a wood
species, the chart answers our question. But what if we're
interested in strength and R-value? First we choose the species
with the greatest strength based on a table, then we look for
that wood in a table of R-values. We find the strongest wood is
nowhere near the best in terms of R-value. If we choose the wood
with the best R-value, it's nowhere near the strongest. At this
point we have to choose which is more important to us: strength
or R-value. Maybe introducing a third characteristic will help
sort things out. So, let's consider decay resistance. Using the
Wood Handbook: Wood As An Engineering Material issued by the U.
S. Forest Products Laboratory, we search for the most
decay-resistant species. We find that in the matter of decay
resistance the handbook groups woods into categories of
"highly," "moderately" and
"somewhat." Most of the 26 or so species of wood rank
as highly or moderately decay resistant, so the table is of
limited help in settling disputes between individual species.
With decay resistance, we introduce another aspect of the
argument. How will the house be built and maintained? Is it
going to be left natural or treated with some preservative? Will
the wood be in contact with the soil or isolated from it? Will
the house be built to allow water to stand on the wood or will
it be built to protect the logs from prolonged exposure to
moisture?
No log home company that I am aware of recommends leaving
exposed wood untreated. Thus, any wood will likely receive a
treatment to prevent de cay. Accepted building techniques
require that wood be protected from prolonged contact with
water. This means including roof overhangs and elevating wood
above r ground level. Often these techniques are mandated by
building codes. Treating logs and trim with a preservative and
using proper building techniques reduces differences in decay
resistance between wood species. With proper treatment and
proper construction methods, any species can be considered
highly resistant.
The same applies in the area of insect resistance. There is no
wood used in log homes that is insect proof. Among woods, there
are varying amounts of insect resistance, but any type is
susceptible to certain insects. To prevent insect infestation,
virtually all log homes receive some type of insect treatment.
The treatment becomes the basis for insect resistance, making
all woods effectively "highly" insect resistant. (As
long as the treatment is applied correctly and at proper
intervals.)
Let's move on to another characteristic: shrinkage. Wood species
vary in the amount they shrink, but all are subject to some
shrinkage. Shrinkage is important because it plays a role in
settlement, ,this in turn affects how a log house should be
designed and built. The construction techniques used to
accommodate an inch of settlement in an 8-foot all are the same
as those used to accommodate 3 inches. Because shrinkage and
settlement vary not only between wood species, but between
individual logs, most systems are designed to accommodate
shrinkage within a range. It doesn't matter whether the logs
settle more or less. It is important that the house be designed
and built to handle whatever amount takes place.
Finally, we can look at characteristics that affect appearance,
like checking and knots. Normally, these don't affect the
strength or energy efficiency of a log wall so their concern is
mostly aesthetic.
Beauty is truly in the eye of the beholder. One person's idea of
rustic may be far from another's. My own home has been judged
rustic and contemporary by different people in the same day! So
here, a table of values ranking wood as more or less knotty or
likely to check has little meaning. Your personal taste is the
judge.
By now you've probably gathered that I'm not going to name a
"best" wood for a log home. Even though I favor and
sell certain species of woods and have my own personal
preferences, I recognize that when someone asks me which wood is
best they are really asking not one but a dozen questions. The
only fair reply is to give them a dozen answers and let them
sort out which is most important to them. But, since many people
find little comfort in that response, I've developed a more
comprehensive answer: Every wood being used by log home
companies today is capable of producing a house that will give
pleasure to its owners throughout their life. Every wood used is
also capable of producing a house that will be a source of
aggravation and disappointment.
To ensure a lifetime of enjoyment, choose the wood and building
system that gives the style and appearance you want. Then make
sure that construction follows the manufacturer's instructions
precisely, and pay careful attention to proper maintenance. If
you do those things, you will find that you have chosen the best
wood for your home. |
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