Striking a Winning Balance: Can You Overprotect Your Building?
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By Barry Reid, LEED AP Sustainability Manager, Georgia-Pacific LLC
Building a truly sustainable building requires the deft touch of a racecar crew
chief. To ensure his vehicle is competitive, the chief oversees a variety of
disparate but integrated efforts — finely-tuning the engine, tinkering with the
suspension, maximizing tire wear, analyzing track conditions and applying
aerodynamic principles to determine the final set-up. And to cross the finish
line, these and countless other key factors — like the skill of the driver —
must strike the proper balance.
So, too, the creation of a winning structure, one that blends moisture
management, energy efficiency, indoor air quality and countless other factors to
result in a champagne cork-popping building.
But ours has typically been an industry of independents – designers, builders,
manufacturers — who are experts in their own field but not necessarily
accustomed to working as a team to achieve the most sustainable building
possible. How do we guarantee in this demanding era of environmental acronyms –
with LEED® in the lead — that we work with pit-crew precision throughout the
design and construction process?
Clearly, we must continue to build our buildings and homes to be increasingly
more energy efficient. This requires superior moisture management, durability,
and indoor air quality strategies to make certain that buildings perform well
into the future. But in doing so, the challenges are many – and they must be
addressed in order to orchestrate a balance when designing, constructing and
maintaining sustainable buildings.
Let’s consider a common but rarely considered moisture management conundrum –
can you actually over-protect your building?
With improvements in construction practices, building envelopes have become
“tight”— meaning builders are doing a much better job of preventing moisture and
air from infiltrating a building. But what happens when it does – say through a
leaky window, an improper flashing detail, or a misplaced vapor retarder? The
same system that works to prevent moisture from accumulating in the wall can
serve to keep moisture from getting out, thus actually increasing the likelihood
of moisture- and mold-related damage.
Conversely, the misconception that buildings should “breathe” can mean there is
little control over the infiltration of air and moisture being brought into the
building. If this happens in a well-insulated wall (chances are we won’t ever
see less-insulated walls), moisture can accumulate. Does anyone really want to
live in the drafty, leaky log cabins of our ancestors? Although they certainly
were able to dry out quickly after a storm and didn’t grow mold, they were not
Properly installed and secured vapor retarders and air barriers are currently
the tools used in reducing the likelihood that moisture can enter a wall
assembly. But several factors should be addressed before choosing what grade and
where to install vapor retarders, including the climate zone and the building’s
use and tenants. When working with vapor retarders, the objective is keeping
moisture migration in check, keeping in mind the fact that moisture, water vapor
always moves from the warm side of building assemblies to the cold side.
The critical factors when deciding where to install vapor retarders is to
address the climate where the building is located. For example, in a warm
climate, like Miami, the warm side of a building is always the outside, so you
would install the vapor retarder toward the exterior walls. In Boston, it’s
reversed… the warm side is the inside, so you would address moisture movement by
installing the vapor retarder toward the interior walls.
Of course, the reputation-enhancing rewards for getting it done right can be
substantial. Even though moisture control is referenced either directly or
indirectly in Energy Efficiency, Resource and Materials, and Indoor
Environmental Quality sections in virtually every green building code, standard
and program, there are many ways to make mistakes that actually make things
worse. One classic example of a mistake having to do with moisture management is
installing vinyl wallpaper over wallboard in a hot humid climate… the result – a
high risk for mold growth! Another is putting vapor retarders on the inside wall
of a structure in a hot humid climate.
The point is – there are multiple paths and trade-offs to ensure moisture
control is addressed. It is important to look at the climate zone, the building
orientation and landscaping, the architecture-and shape of the roof and
building, the windows and doors, the day lighting, the HVAC system and how it is
sized, and the material choices that have been made before making a final
Finding the right path that strikes a balance that is appropriate for that
particular structure and its long-term performance means that you – and your
building – will land in Victory Lane.
About the Author: Mr. Reid has 22 years experience in the Building
Products industry. He is currently Sustainability Manager for Georgia-Pacific
LLC Building Products where he serves as Subject Matter Expert on green building
codes, standards, and programs. He works with product development and management
teams integrating sustainable and building science principles into
Georgia-Pacific products and processes. Current green building activities
include being a member of the Gypsum Association’s Ad-Hoc Committee on
Sustainability and is the chair of the American Wood Council’s Green
Building-Codes and Standards Technical sub-committee. Mr. Reid has a B.A. from
the University of Oregon, College of Business Administration. You can contact
Mr. Reed at firstname.lastname@example.org.