Changes Coming in the 2021 IBC Requirements for Exterior Walls on Commercial Buildings

28 • IIBEC Interface October 2022
Changes Coming in the
2021 IBC Requirements
for Exterior Walls on
Commercial Buildings
By Jeffrey H. Greenwald, PE, CAE, and Lorraine Ross
This paper was originally presented at the 2021 IIBEC International Convention and Trade Show.
The year 2020 delivered many
unexpected changes in our
personal lives as well as the
way we do business. However,
in the world of building codes,
the usual three-year update
cycle for building, fire, and energy codes continued
as usual, leading to the publication of
the 2021 International Code Council (ICC)
suite of codes, which include the International
Building Code (IBC)1 and the International
Energy Conservation Code (IECC).2 Additionally,
review of two major reference standards that
affect commercial buildings resulting in updated
versions were released in 2019:
• ANSI/ASHRAE/IES Standard 90.1-2019:
Energy Efficiency Standard for Buildings
Except Low-Rise Residential Buildings3
• NFPA 285—2019: Standard Fire Test
Method for Evaluation of Fire Propagation
Characteristics of Exterior Wall Assemblies
Containing Combustible Components4
This article highlights key code and standards
revisions regarding the use of combustible
building products in commercial buildings and
reviews how code compliance techniques can
be used to demonstrate fire safety for certain
deviations from tested wall assemblies.
THE IMPORTANCE OF RESILIENCE
Although codes and reference standards are
often viewed as “stand-alone” requirements, it
is important to recognize the contribution of
energy and building codes to improving the
resilience of buildings in both the commercial
and residential sectors. Some of the leaders
in this effort include the American Institute
of Architects, the US Federal Emergency
Management Agency, and ICC, among others. In
the white paper “Resilience Contributions of the
International Building Code [IBC],”5 ICC noted,
The National Academies (2012) have
defined resilience as, “the ability to
prepare and plan for, absorb, recover
from, and more successfully adapt to
adverse events.” The building industry,
including organizations representing
planning, design, construction,
ownership, operation, regulation
and insurance, have embraced
the definition put forward by the
National Academies. Nearly 50 building
industry organizations signed on
to an Industry Statement on Resilience
recognizing the need for coordinated
action through research, advocacy,
education, planning and response.
The ICC white paper identifies specific parts
of the IBC that address the problems of hurricanes,
earthquakes, floods, wildfires, and other
natural disaster events.
Like building codes, energy efficiency codes
are also important in mitigating the impacts
of a changing climate. The origins of energy
efficiency codes and standards were rooted
in energy supply issues and the rising costs of
heating and cooling buildings. While these two
drivers are certainly still important, energy efficiency
requirements are increasingly important
for addressing resiliency.
Of course, a resilient building alone cannot
deliver full protection from natural disasters.
Community resources must be leveraged to provide
the level of resilience that must be reached
to mitigate these risks. To that end, the ICC,
along with the US Resiliency Council and the
Meridian Institute, facilitated the formation
of the Alliance for National and Community
Resilience, a coalition aiming to develop a “system
of community benchmarks—the first system
of its kind in the United States—that will allow
local leaders to easily assess and improve their
resilience across all functions of a community.”6
CODE UPDATES
ASHRAE 90.1-19 and 2021 IECC
Generally, minimum requirements for the
energy efficiency of commercial buildings is
established by the IECC, which recognizes the
ASHRAE 90.1 standard as the most widely
used compliance method. However, states may
enforce specific codes, such as California’s Title
24 Building Energy Efficiency Standards.7
Further complicating matters, some green building
rating systems, such as LEED, recognize
ASHRAE 90.1 but not necessarily the IECC.
The latest revisions of ASHRAE 90.1 and
IECC both include energy efficiency gains for
commercial buildings. Some high-level changes
for each are highlighted here.
The 2021 IECC energy efficiency gains are
estimated to be in the range of 8% to 15%. The
IECC revisions include the following:
October 2022 IIBEC Interface • 29
• Disclosure of the energy compliance path
(prescriptive, performance, etc.) on the construction
documents
• Climate zones that are harmonized with
ASHRAE 90.1
• For insulation materials, such as blown or
draped products, without an observable
R-value mark, an insulation certificate from
the installer that documents the installed
R-value of the material
• A permanent thermal envelope certificate,
posted in specified locations, to document:
— R-value of insulation installed in or on
ceilings, roofs, walls, foundations and
slabs, basement walls, crawl space walls
and floors, and ducts outside conditioned
spaces;
— U-factors and solar heat gain coefficients
(SHGC) of fenestration; and
— results from any building enclosure airleakage
testing.
• Energy improvements in building enclosure
U-factors and R-values that result in increases
in continuous wall insulation
ASHRAE 90.1-2019 changed over 100
measures from the 2016 version.8 The US
Department of Energy is currently reviewing
the updated standard to determine its energy
efficiency improvements.
Some of the changes in ASHRAE 90.1-2019
include the following:
• For the first time, commissioning requirements
in accordance with ASHRAE/IES
Standard 202: Commissioning Process for
Buildings and Systems9 are mandatory.
• Minimum criteria have been upgraded for
SHGC and U-factor for fenestration for all
climate zones.
• Air-leakage requirements are clarified.
• Changes in building enclosure U-factors and
R-values, resulting in likely increases in continuous
wall insulation.
• All compliance paths have specific rules
related use of renewables and lighting.
2021 IBC
The IBC is a model building code for commercial
construction, which is then adopted by
states and jurisdictions. Compliance with local
building code regulations, which may vary from
the IBC model code, is imperative.
The increasing use of energy-efficient continuous
insulation and innovative wall assemblies
places a greater emphasis on fire performance
of exterior walls, which is evaluated using NFPA
285.Generally, IBC requires NFPA 285 testing for
combustible exterior wall assemblies, including
combustible cladding, foam plastic insulation,
or combustible water-resistive barriers (WRBs),
installed on Types I, II, III, IV buildings of certain
heights (see above sidebar for information
on IBC classification of building types). Type
V wood construction does not require NFPA
285 testing.
The 2021 IBC requirements for the fire
safety of exterior walls containing combustible
claddings, WRBs, and foam plastic insulation
are found in Chapter 14, “Exterior Walls,” and
Chapter 26, “Plastic.” Chapter 14 includes the
minimum requirements for exterior walls; exterior
wall coverings; openings in the exterior wall;
exterior windows and doors; and architectural
trim. The provisions detail performance requirements
regarding weather protection, structural
performance, moisture control, reaction to fire,
and flood resistance. Other provisions in the
chapter address materials of construction, installation
of wall coverings, and use of combustible
materials on the exterior side of exterior walls.
With respect to exterior walls, there are
important revisions in the 2021 version of
Chapter 14 regarding the use of moisture vapor
retarders, particularly when used in combination
with continuous insulation, spray foam insulation,
and hybrid insulation systems. Other revisions
clarify fire performance requirements and
improve the consistency of fire testing of exterior
walls containing combustible components.
Table 1 summarizes key changes in the 2021
IBC version of Chapter 14.
IBC Chapter 26 contains provisions for
the use of foam plastic insulation in exterior
walls, which were extensively described in a
paper delivered at the 2019 RCI International
Convention and Trade Show.10 The 2021 IBC
does not make substantive changes to use in
exterior walls (Section 2603.5), but these revisions
have been made to other sections:
• A definition for spray-applied foam plastic is
added.
• New Section 2603.1.1 requires spray-applied
foam plastic to comply with both Section 2603
and ICC 1100.11
• Section 2607.5 adds a height restriction of 75
ft above grade plane for light-transmitting
plastic wall panels, where previously there
was no height limitation.
NFPA 285-2019
As stated earlier, the IBC uses the NFPA 285
wall assembly fire test to evaluate the flammability
characteristics of exterior, non-load-bearing
wall assemblies/panels that contain combustible
components, including combustible claddings,
insulation, and many air- and water-resistive
barriers. The multistory test assembly measures:
• Flame propagation over the exterior wall surface
• Vertical flame propagation within the combustible
core or components
• Vertical flame propagation over the interior
surface from one floor to the next
• Lateral flame propagation to adjacent compartments
NFPA 285 is a full wall assembly test conducted
on a test specimen that is 18 ft high and
13 ft 4 in. wide, with a 78-in.-wide window opening.
The fire sources are two gas burners (one
International Building Code (IBC)
Classification of Building Types
• Types I and II: The various building elements are made up
of noncombustible materials.
• Type III: Exterior walls are made of noncombustible materials,
and the interior building materials are of any material
permitted by the IBC.
• Type IV heavy timber: Exterior walls are made of noncombustible
materials, and the interior elements are made of solid
or laminated wood without concealed spaces.
• Type V: Structural elements for both exterior and interior
walls are of any materials permitted by the IBC—usually
combustible construction.
Source: Chapter 6 of the International Building Code.1
30 • IIBEC Interface October 2022
Section Changes
1401: General No changes
1402: Performance Requirements
Subsection 1402.5:
• Changed title from “Vertical and Lateral Flame Propagation” to
“Water Resistive Barriers”
• Clarifies that combustibility of components is determined in accordance
with Section 703.5
• Clarifies Exception 2 fire testing for combustible WRBs, ASTM E1354 test
conditions, and ASTM E84 (UL 723) test specimens
1403: Materials
Subsection 1403.2 (Water-Resistive Barrier):
• Reorganized prescribed performance standards for WRBs into a list
• Added ASTM E331 in accordance with Section 1402.2 as a prescribed
performance standard
New subsection 1403.14 (Attachments through Insulation):
• Guides users to applicable sections under Section 2603 for situations
when exterior wall covering attachments to the building structure are
made through foam plastic sheathing
1404: Installation of Wall Coverings
Subsection 1404.3 (Vapor Retarders):
• Editorial reorganization for ease of use
• New and revised provisions regarding use of vapor retarders
(Class I and II, and Class III) with continuous insulation, spray foam
insulation, and hybrid insulation systems
• New provisions regarding use of Class I and II vapor retarders (ASTM
E96 Procedure A—Desiccant Method) that have vapor permeance
>1.0 perm when tested using ASTM E96 Procedure B—Water Method
• New and revised prescriptive guidance regarding permitted
conditions (climate zone and wall configuration) and exceptions
where Class I and II, and Class III vapor retarders are permitted in
combination with continuous insulation
1405: Combustible Materials on the Exterior
Side of Exterior Walls No changes
1406: Metal Composite Materials
Subsection 1406.10 (Type I, II, III and IV Construction):
• Simplified threshold for NFPA 285 testing to installations above 40 ft in
height
Subsection 1406.11 (Alternate Conditions):
• Eliminated complex provisions regarding installations on buildings of
Type I, II, III, and IV construction up to 50 ft in height and 75 ft in height
1407: Exterior Insulation and Finish Systems No changes
1408: High-Pressure Decorative
Exterior-Grade Laminates
Subsection 1408.11 (Alternate Conditions):
• Revised to eliminate provisions regarding installations up to 50 ft in
height
1409: Plastic Composite Decking No changes
Note: WRB = water-resistive barrier.
Table 1. Notable revisions to Chapter 14 of the 2021 International Building Code1
October 2022 IIBEC Interface • 31
room burner located inside the first floor, and
another window burner on the exterior side).
Both of these burners are needed to simulate
real conditions where a fire may originate from
within the structure, all interior materials are
burning (flashover), and the fire suppression
system has failed (Fig. 1).
The wall assembly is mounted on the face of
the apparatus (Fig. 2). Thermocouples are fitted
on the exterior wall surface, in the wall cavity
air space and stud cavity, and in the insulation.
After a testing period of 30 minutes, a successful
test will show no flame propagation to the
second-story room and no thermocouple may
exceed 1000°F. Flame spread cannot exceed 10
ft above the top of the window, nor more than
5 ft laterally from the centerline of the window
(Fig. 3).
As with other standards-setting organizations,
NFPA periodically updates its standards
using a consensus-based process. For the 2019
edition of NFPA 285, substantial technical
changes were made to the test method. The critical
technical changes include an expanded scope
to encompass any construction type, revisions to
include both load-bearing and non-load-bearing
assemblies, and new sections added to Chapter 5
to address window header construction and the
location of joints and seams in the test specimen
assembly. Additional information is required for
NFPA 285 test reports. Table 2 summarizes key
changes in NFPA 285-2019.
Compliance Pathways for Exterior Walls
Requiring NFPA 285 Testing
As described previously, combustible exterior
wall assemblies must demonstrate compliance
with the acceptance criteria of NFPA 285. To
accomplish this, the exact wall assembly, with
all components specified, is tested by an accredited
laboratory. Taken at face value, the criteria
seem to require that every wall assembly configuration
undergo a separate test. However,
considering the variables regarding foam plastic
insulations, claddings, attachment methods,
framing, and other factors, the number of tests
quickly becomes unmanageable. The situation
is more challenging because only a limited
number of accredited testing laboratories perform
NFPA 285 tests.
Another compliance route is through the
use of an engineering judgment (EJ). For exterior
wall assemblies complying with NFPA
285, an EJ is a report that provides a comparative
analysis of the effects that one or more
variations to a tested assembly will have on
compliance with NFPA 285 acceptance criteria.
These reports are prepared by qualified
individuals and organizations, and must be
based on full-scale test data. EJs may be general
or specific to one construction project or project
condition, and may include both qualitative
and quantitative elements. EJs using an NFPA
285 full test report are within the scope and
intent of IBC 104.11, “Alternative Materials,
Design and Methods of Construction and
Equipment.” However, at the end of the process,
the Authority Having Jurisdiction (AHJ)
makes the final decision about whether such
EJs are acceptable for use on a specific project.
In March 2018, efforts to improve the
transparency and consistency of EJs led to the
NFPA Committee on Fire Tests approving the
formation of a task group to develop guidance
for extending NFPA 285 test results. Under
the task group, experts have collected experience
and industry best practices in an annex
to NFPA 285 for guidance when extending test
results for assemblies meeting NFPA 285. The
annex will provide guidance regarding items
for which evaluation and EJ are more com-
Figure 1. NFPA 2854 test assembly.
Figure 2. Twostory
test with
interior and
exterior burners.
Figure 3. NFPA 2854 fire test parameters and pass criteria.
32 • IIBEC Interface October 2022
Chapter Changes
Title; Chapter 1: Administration
Language from the Title, Scope, Application, and Purpose
revised to include:
• Both load-bearing and non-load-bearing wall assemblies
• All International Building Code construction types
Chapter 3: Definitions
• “Limited-combustible (material)” definition added
• “Noncombustible material” definition revised
• “Test specimen” definition revised
Chapter 5: Test Specimens
New section 5.7.1 (General):
• Clarifies that the test specimen assembly shall be representative
of field installations and installed in accordance
with the manufacturer’s instructions
• Adds that the test specimen wall framing system may be of
wood studs (previously, only steel studs were permitted)
New section 5.7.2 (Joints and Seams):
• Includes new requirements that the exterior veneer of the
test specimen must contain
— At least one vertical joint/seam
— At least one horizonal joint/seam
— Exceptions are provided for exterior insulation and
finish systems, standard stucco systems ≥ ¾ in. thick,
and systems designed to not have horizontal joints or
continuous vertical joints
• The required joint/seam must be
— For horizontal – Continuous across the specimen and
located between 1 ft and 3 ft above the window opening
— For vertical – Continuous up the full height above the
window and located within 12 in. of the centerline over
the window opening
New section 5.7.3 (Window Headers):
• Standardizes the material and configuration details for
closure of the window opening: header, jambs, and sill
• Allows for nonstandard closures of window opening, but
it shall represent the as-constructed condition, and the
details (drawings and descriptions) shall be included in
the test report
Chapter 7: Calibration Procedure
Section 7.1.13:
• Revised allowable limits on calibration temperature values
to range of -10% to +20% (previously, limits were ±10%)
Chapter 8: Fire Test Procedure
New section 8.1.8:
• Adds a ±10% tolerance for gas flow rates when it is demonstrated
that burners must follow different flow rates to
comply with the required calibration temperatures and
heat fluxes
Chapter 9: Data Collection and Observation
Section 9.1.2:
• Removes the 10-minute observation period after burner
shutoff
Section 9.4:
• Revised and reorganized for clarity
Chapter 11: Report
Section 11.1:
• Adds requirement for the report to include drawings,
descriptions, and other details regarding the window opening
and the closure of that opening
• Adds requirement to report date and results (temperature
and heat flux) of the most recent calibration
Table 2. Notable revisions in NFPA 285-20194
October 2022 IIBEC Interface • 33
monly requested or required today. These items
include analyses regarding base walls, exterior
sheathing, WRBs, air gaps, exterior insulations,
drainage media, exterior claddings and attachment
systems, and the window perimeter. Two
key elements of the guidance will be that these
wall assemblies are treated as systems that meet
the requirements, and that analyses are based
on assemblies meeting NFPA 285 acceptance
criteria. The annex will likely also stipulate specific
limitations to the scope of analysis. These
stipulations will likely indicate that changes to
the assembly under evaluation are normal and
reasonable within the limits of standard construction,
explain how to analyze multiple changes, and,
importantly, acknowledge that it is not possible
to analyze every configuration, every potential
change, or every combination of changes to a tested
configuration.
The annex is on track for submission under the
current (fall 2021) NFPA revision cycle for inclusion
in the 2022 edition of NFPA 285. We can
expect more detailed information on NFPA 285
EJs as the NFPA Fire Test Committee completes
its work on the EJ guidance document.
REFERENCES
1. International Code Council (ICC). 2021 International
Building Code. Country Club Hills, IL: ICC, 2021.
2. ICC. 2018 International Energy Conservation Code. Country
Club Hills, IL: ICC, 2018.
3. American National Standards Institute (ANSI), ASHRAE,
and Illuminating Engineering Society (IES). ANSI/
ASHRAE/IES Standard 90.1-2019: Energy Efficiency
Standard for Buildings Except Low-Rise Residential
Buildings. Peachtree Corners, GA: ASHRAE, 2019.
4. National Fire Protection Association (NFPA). NFPA
285—2019: Standard Fire Test Method for Evaluation of
Fire Propagation Characteristics of Exterior Wall Assemblies
Containing Combustible Components. Quincy, MA: NFPA,
2019. https://www.nfpa.org/codes-and-standards/
all-codes-and-standards/list-of-codes-and-standards/
detail?code=285.
5. ICC. 2019. “Resilience Contributions of the International
Building Code” white paper. Accessed April 24, 2021.
https://www.iccsafe.org/wp-content/uploads/19-17804_
IBC_Resilience_WhitePaper_FINAL_HIRES.pdf.
6. Alliance for National and Community Resilience. “Who
We Are and What We Do.” Accessed April 24, 2021. http://
www.resilientalliance.org/about.
7. California Energy Commission. “2019 Building Energy
Efficiency Standards.” Accessed April 24, 2021. https://
www.energy.ca.gov/programs-and-topics/programs/
building-energy-efficiency-standards/2019-buildingenergy-
efficiency.
8. ASHRAE. “ASHRAE Releases Expanded, Revised Version
of Standard 90.1,” news release, October 25, 2019. https://
www.ashrae.org/about/news/2019/ashrae-releasesexpanded-
revised-version-of-standard-90-1.
9. ASHRAE and IES. ASHRAE/IES Standard 202:
Commissioning Process for Buildings and Systems. Peachtree
Corners, GA: ASHRAE, 2018.
10. Koscher, J., and L. Ross. “Foam Plastic Insulation: Fire Safety
for Exterior Walls on Commercial Buildings.” 2019 RCI
International Conference and Trade Show Proceedings.
Accessed April 24, 2021. https://iibec.org/wp-content/
uploads/2019-cts-koscher-ross.pdf.
11. ICC. ICC 1100-2019 Standard for Spray-applied
Polyurethane Foam Plastic. Country Club Hills, IL: ICC,
2019.
Please address reader comments to chamaker@
iibec.org, including “Letter to Editor” in the subject
line, or IIBEC, IIBEC Interface Journal, 434
Fayetteville St., Suite 2400, Raleigh, NC 27601.
Jeffrey H. Greenwald, PE,
CAE, is technical consultant
with the North
American Modern
Building Alliance
(NAMBA). In this role,
he supports implementing
the NAMBA’s mission,
work plans, and
building codes and standards
development.
Greenwald is a registered
professional engineer in Virginia and earned a
master’s of civil engineering degree from the
University of Delaware. He was awarded the ASTM
Alan H. Yorkdale Memorial Award for best paper
concerning masonry in 2004 and 2005.
Lorraine Ross has been
involved for over 30 years
in all aspects of the building
products industry,
including manufacturing,
technical service,
and regulatory issues
such as building code
development, compliance,
and testing laboratory
experience. As
president of Intech
Consulting Inc., she is actively involved in building
and fire code development through the International
Code Council, the National Fire Protection
Association, and a variety of state code development
activities, particularly regarding foam plastic insulation.
She is a member of the Florida Building
Commission Roofing Technical Advisory
Committee and has delivered many presentations
on building code topics at a variety of industry
conferences.
1083527_Editorial.indd 1 21/09/22 12:10 PM
Jeffrey H. Greenwald,
PE, CAE
Lorraine Ross