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The following documents provide more detailed technical information and facts regarding various applications using extruded polystyrene foam insulation products.
Foundations and Below-Grade Applications
EXTRAORDINARY EPS MOISTURE
PERFORMANCE CLAIMS LACK ORDINARY EVIDENCE
INDEPENDENT-EXPERT REVIEW OF SCIENTIFIC EVIDENCE CLEARLY CONFIRMS XPS EXHIBITS SUPERIOR PERFORMANCE RELATIVE TO EPS IN BELOW-GROUND APPLICATIONS
Technical information from an EPS-industry
commissioned study attempted to show the relative performance between
extruded polystyrene (XPS) and expanded or molded polystyrene (EPS)
insulation products used in below-ground applications. An
independent-expert was hired to provide an exhaustive technical
review of the study and its performance claims. The review
included a comprehensive analysis of the following:
- National and International Scientific Literature Historically-available
- A statistical analysis of reported technical data on this subject
to date
- A review of the new performance claims published by certain
EPS manufacturers and their trade association—the Expanded
Polystyrene Molders Association (EPSMA)
Contrary to current EPS-industry claims,
the expert concluded that the at-large scientific evidence clearly
shows a consistent trend of XPS exhibiting superior performance
relative to EPS in below-ground applications.
The EPS-reported claims are based on
a very limited study. This study has not been made publicly available
nor has it been subjected to independent peer review. After
three months and several requests for the underlying EPS technical
study, EPSMA refused to disclose the entire report, including its
test methodologies, sample-handling procedures and underlying data
as they received it from Twin Cities. Without the entire
report, proper technical analysis cannot be verified to determine
whether there is any scientific merit in its conclusions. Click
to See: EPSMA’s
Response Letter denying review.
To inform the building and regulatory
communities a technical bulletin was prepared by an independent
expert who questions the validity and basis for these unfounded
claims made by the EPS industry and EPSMA. This important technical
bulletin is available for download by clicking here: Volume
3, Issue 1. The following two facts summarize
the key findings:
The International Code Council (ICC) Building Code
and the ASCE 32-01 Standard Recognize that XPS
Performs Better than EPS in
Below-Ground Applications
- ASCE 32-01 consensus standard, referenced in Sec.1805.2.1
of the 2006 Internatational Building Code (IBC), and Sec. R403.1.4.1
of the International Residential Code (IRC), the nation’s
most widely-used model building codes, recognize that XPS maintains
a higher R-value retention in below-ground foundation insulation
applications.
- IN FACT, the IRC includes an extra precaution prohibiting
the use of EPS and only allowing XPS in horizontal applications
(see IRC Table R403.3, footnote e).
- Both the ASCE 32-01 and ICC codes follow consensus procedures
engaging the public and a broad array of industry experts
when establishing codes and standards.
XPS Performs Better is
Confirmed by a broad body of Recognized Scientific Literature
- ASCE 32-01 committee considered “numerous field studies” to
properly characterize differences in performance of XPS and
EPS and to establish appropriate thermal design properties
for below-ground use. This broad body of data firmly
contradicts the questionable EPS-commissioned industry study
mentioned above.
Extraordinary claims that contradict
established and documented codes and standards positions must
be supported by THIRD-PARTY, PEER-REVIEWED and fully-vetted SCIENTIFIC
evidence. So, before you accept
product performance claims from any single study, be sure to get
all the facts.
Roof Systems
Direct to Steel Deck with XPS
Sustainable R-Value with XPS Roof Systems
Mythunderstandings about XPS Use in Direct to Steel Deck
Protecting against solar heat damage in XPS roof systems
Walls
XPS Sheathing Franklin/APC Life Cycle
How-To Design Guide for Installing Foam Sheathing
Design Supplement for How-To Design Guide
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