| NOVEMBER
21, 2005
All homes built to today’s energy
efficiency encouraging building codes are candidates
for mold problems, according to one of the nation’s
leading consultants in energy efficiency and green building.
But, it doesn’t have to be that
way said Mark LaLiberte, president of Minneapolis’
Building Knowledge Training Services, adding that a
Lake Oswego-based builder is ahead of the curve in preventing
the expensive problem which has many builders afraid
to even say the word.
“All housing exteriors develop
cracks over time...cracks in siding, cracks at exterior
seams and window and door caulking,” LaLiberte
said during a stop at Renaissance Homes Lake Grove office.
LaLiberte is one of the most sought after consultants
in the country on green building techniques and on ways
to avoid mold problems, a serious problem throughout
the US, but particularly in moist climates like the
Pacific Northwest.
LaLiberte’s visit to Renaissance
Homes was the second in the last 12 months. Sponsored
by Dupont Tyvek Building Materials, he was working with
Ranaissance’ “Living Green” to fine
tune the company’s three-year-old program of building
all its homes to exacting energy efficiency and other
“green” standards, including systems which
“meet and exceed Earth Advantage specifications
and virtually guarantees there won’t be mold problems,”
according to Randy Sebastian, Renaissance’ president.
A 2004 consumer magazine study turned
up serious problems in 15 percent of the new houses
built in America each year, which translates into 150,000
homes. Those problems can easily translate into moisture
issues, which lead to mold. And, that figure includes
homes “in someplace dry like Tuscon, where mold
won’t be a big problem. In a marine climate like
here, the figure undoubtedly is higher,” LaLiberte
said.
Today’s home owners want draft-free,
comfortable energy efficient homes. Code changes, aimed
at making homes that way mean air tight construction
techniques which are less forgiving than in older homes
that sometimes were so drafty that curtains visibly
moved on windy nights, he said.
Window caulking is particularly susceptible.
Half of all windows will develop caulking leaks within
10 years, said LaLiberte, citing a Canadian study. “Failures
show up in eight or nine years in dry climates and in
three to four years here,” he said. And, if rain
does get into one of today’s homes, house wrap,
siding, insulation and caulking give it little chance
to dry out.
“It takes about four hours for spores to develop
once rain water is trapped in a wall and about four
days for those spores to begin looking for new material
to eat,”he said.
LaLiberte praised Renaissance for “setting
a bench mark” with systems designed to eliminate
the moisture penetrations that lead to mold.
In addition to pan flashing at the
bottom of windows and doors, Renaissance is the only
major builder in the metropolitan area using a siding
system in all its homes which eliminates that problem.
Developed in Vancouver BC, this particular
system is called Rainscreen. It is an exterior wall
system that firs out the siding by a half inch to allow
a channel of air circulation between the siding and
the house wrap. This circulates air throughout the exterior
of the house so it can “breathe” better.
Any moisture which invades the space just runs through
and out the bottom rather than seeping behind house
wrap or plywood and causing mold.
Rainscreen eliminates the threat of
water incursion if the caulking fails.
As part of its moisture barrier, Renaissance
has Portland’s Milgard company install its own
windows in all homes, which guarantees better fit, lessening
the likelihood of early caulking failure. With Rainscreen
and the window installation package, Living Green exceeds
code specifications for water resistance.
The firm also puts pan flashing at
the bottom of windows and doors which channel water
away from the natural pooling areas.
La Liberte estimates that about 20-30 percent of metropolitan
area builders use pan flashing.
“Builders are slowly coming around
because the problems of mold are so extensive and expensive
to fix. Pan flashing is the first step. The next stage
will be a Rainscreen type of siding system. Every builder
should do this, especially in a damp climate,”
he said.
Sebastian acknowledged that adding
pan flashing and Rainscreen costs $3,000-$4,000 per
house, “but it’s well worth it. That’s
much less than having to repair extensive damage from
mold.”
Renaissance Homes
16771 Boones Ferry Road
Lake Oswego, Oregon 97035
Voice: 503-636-5600
Fax: 503-635-8400
Emergency Service: 503-496-0711 or 866-567-6225
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