Architectural Record 2015-04

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material performance requirements including
fire containment and control in some cases.
And of course, the owner and design team
will care about the economics of the system
not to mention the final appearance and other
considerations such as wall thickness and how
that integrates with the rest of the building
construction. Altogether, a framed wall assembly
is a collection of a lot of different materials
that need to come together to meet all of these
different requirements and will directly impact
the long-term comfort of the occupants, energy
use of the building, and even the quality of the
indoor environment.
A properly designed and specified framed
wall assembly delivers on the promise of
overall integrity through a scientific analysis
of materials and an understanding of the
compatibility of different components of the
assembly. Among the more significant factors
is the clear continuity of each of the needed
barriers (thermal, water, air, vapor) so that
breaches do not occur and undermine the
performance or integrity of the wall. But we
are probably all too aware that defects and
even failures in wall systems can and do occur.
Why? There are known causes in both the
design of walls and in their construction. For
a designer, a lot of technical information has
become available in recent years that can seem
contradictory at times, making a clear design
decision seem difficult to discern. Sometimes
new or unproven systems or materials are
specified without fully reviewing them only
to discover too late that they do not live up to
expectations. In other cases, failures may occur
because different materials were incompatible or
not properly integrated or interfaced into other
construction systems. And there is also the
thought that a single product can take care of a
particular need without providing any back up
or contingency in the design in case something
does go awry.
There is another more basic, and common,
mistake that can be made by design professionals
too, namely to ignore climate differences found
in different locations. A framed wall assembly
that works just fine in one location may produce
significantly different results in another. That
is why energy codes and standards, along with
government agencies, have identified and
adopted climate zones as the basis for building
envelope design across the United States. There
are eight identified climate zones ranging from
very warm and humid in the south to much
colder and dryer in the north, and plenty
of variations in between. Before any design,
construction, or permitting processes start, the
proper climate zone must be identified for a given
building and the assembly developed to match
that zone accordingly.
Once bidding and construction begin, there
is often the temptation to “value engineer”
alternatives into the constructed building.
Now in some cases value engineering can be
a legitimate and useful tool. But improperly
applied to frame wall assemblies, it may only save
short-term construction costs at the expense of
reduced long-term performance and potential
cost exposure later on. During construction,
quality control of the installed work is needed to
achieve the intended results of any wall assembly
and the only way to assess that is through routine
inspection of the work as it progresses. This can
help eliminate any questionable construction
practices or work that is inconsistent with the
contract documents, but it can also reveal any
installation or procedural errors that can create
defects that impact the performance of the wall.
Continues at ce.architecturalrecord.com
Peter J. Arsenault, FAIA, NCARB, LEED AP,
is an architect and green building consultant who
has authored over 100 continuing education and
technical publications as part of a nationwide
practice. www.linkedin.com/in/pjaarch
Photo courtesy of CertainTeed Insulation
Numerous demands are
placed on exterior framed
wall construction to provide
structure, protection from
the elements, and integrity of
materials over time.
CONTINUING EDUCATION
EARN ONE AIA/CES HSW
LEARNING UNIT (LU)
EARN ONE GBCI CE HOUR FOR LEED
CREDENTIAL MAINTENANCE
Learning Objectives
After reading this article, you should be able to:
1. Identify and recognize the characteristics
of different types of framed wall
construction related to thermal, moisture,
and air control.
2. Investigate the types of exterior wall issues
and failures that need to be overcome in
order for walls to perform as intended.
3. Assess the options available to design
exterior framed walls that can control heat
transfer, moisture, air infiltration, and mold
prevention.
4. Design wall assemblies and specify
products that can be used in a variety of
building types to meet green building
standards and code requirements.
To receive credit, you are required to read
the entire article and pass the test. Go to
ce.architecturalrecord.com for complete
text and to take the test for free.
AIA/CES COURSE #K1504F
GBCI COURSE #0920002826
CONTINUING EDUCATION
With more than 100 years of experience, CertainTeed Insulation is the only insulation manufacturer with a truly
comprehensive offering to help you achieve optimal comfort, with fiberglass Sustainable Insulation ® , blowing wool,
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