Sustainability Characteristics of SPF Roofing and Insulation Systems

May 15, 2004

April 2004 Interface • 13
SECTION 1
Roofing
Between 1983 and 1996, Dean Kashiwagi surveyed
and documented the performance of more than 1,600 SPF
roofing systems.1 In 1998, René Dupuis published results
of his inspection and evaluation of more than 160 SPF
roofing systems in six different climates of the United
States.2 The surveys conducted by Dupuis and Kashiwagi
are very similar in their conclusions that SPF roofing systems
are highly sustainable. In Kashiwagi’s 1996 report,
the oldest performing SPF roofs were more than 26 years
old, 97.6% did not leak, 93% had less than 1% deterioration,
and 55% were never maintained. Kashiwagi and
Dupuis also noted the physical properties of the SPF did
not diminish over time and that more than 70% of the SPF
roofs were applied over existing systems.1, 2
Energy Savings
Many large companies and institutions have documented
energy savings from the use of SPF roofing systems.
Texas A&M calculated the energy consumption of its
buildings before and after the application of SPF roofing
systems. According to the study of more than eight million
square feet of SPF roofing, energy savings paid for the cost
of Texas A&M’s SPF roof applications in three to four
years.3 How do SPF roofs so dramatically show results of
this type?
As shown on Chart 1, black-surfaced roofs have measured peak
temperatures up to 190˚F on a 90˚F day. If the interior temperature
is maintained at 78˚F, the resultant temperature difference is 112˚F.4
Chart 1: Solar absorbtivity.
I N T R O D U C T I O N
Building owners have used spray polyurethane foam (SPF) as a roofing, insulation, and sealing product for many years.
Recent research and performance studies on SPF applications demonstrate many sustainable characteristics of the material. This
article is divided into two sections. The first section addresses SPF roofing and presents investigative research by René Dupuis
and Dean Kashiwagi, Spray Polyurethane Foam Alliance (SPFA) sponsored projects at Factory Mutual and Underwriters Laboratory,
cool roof research by Lawrence Berkeley Labs, and articles written by roofing experts such as Thomas Smith and Patrick
Downey. Energy studies are courtesy of Texas A&M University.
The second section addresses SPF applications to the interior of a building. The article includes research by Mark Bomberg,
W.C. Brown, Robert Alumbaugh, M.K. Kumaran, N.V. Schwartz, Anthony Woods, and others, in addition to SPFA sponsored projects
with NAHB Research Center and Oak Ridge National Laboratories (ORNL) and field investigations by private companies.
14 • Interface April 2004
According to figures
reported by Mike Watts in
1996, fasteners alone can
reduce the effective insulation
value between 1.5% to 31.5%,
depending on the number and
type of fasteners.6
Detail 1 shows what happens
to a typical roof on a hot
summer day. Dark-colored
membranes absorb radiant
heat. The roof’s surface temperature
rises. Thermal
bridges such as fasteners and
gaps in insulation boards
transport the heat within the
building.
How does SPF reduce
energy costs?
As shown in Detail 2:
• SPF roofing systems
are applied above the
roof deck.
• SPF eliminates thermal
bridging by providing
a continuous
layer of insulation
over existing thermal
bridges in the roof
deck and/or roof
assembly.
• SPF has a very high
aged R-value of
between 6 to 7 per
inch.
• SPF roofing systems
typically are coated
with light-colored,
reflective coatings.
Durability
Performance studies and
research suggest that SPF
roofing systems can last 30
years or more. Additionally,
they require low maintenance,
are resistant to leaks
caused by hail and winddriven
debris, are resistant
to high wind blow-off, can add structural strength, and minimize
moisture damage within the building envelope.7
ORNL reported, “The principal causes of premature roof failure
are moisture intrusion and lack of wind resistance. Moisture accumulation
in roofing systems leads to dripping, accelerated failure of
the insulation and membrane, roof structure deterioration, depreciation
of assets, and poor thermal performance. [See Detail 3.] Similarly, the loss of a roof during a major windstorm not only
causes structural damage but also exposes the building contents to
the elements. The insurance industry identifies roofing as the primary
contributor to disaster-related insured losses.”8
SPF roofing systems limit moisture intrusion because of their
90% closed cell properties. Damage to the system typically does not
cause leaks into the building, and moisture intrusion is isolated to
the areas of damaged foam cells (see Detail 4). As reported by Dr.
Dupuis, “One unique aspect of SPF roofs…is that they are not in
Detail 1
Detail 2
April 2004 Interface • 15
immediate danger of leaking,
providing the penetration
does not extend all the way
through the foam.”2
SPF roofing systems have
exceptional wind uplift resistance.
Field observations of
SPF performance during
Hurricanes Allen, Hugo, and
Andrew led the industry to
conduct laboratory testing of
SPF systems at Underwriters
Laboratories and Factory
Mutual. SPF’s wind uplift
resistance exceeded the
capacity of UL’s testing
equipment. UL also observed
that SPF roofs applied over
BUR and metal increased the
wind uplift resistance of
those roof coverings. Factory
Mutual’s testing showed
similar results over concrete,
metal, and wood.9, 10
According to Dr. Dupuis
and other industry experts
such as Thomas Smith and
Richard Fricklas, SPF is a
very good impact absorbing
material. Hail and winddriven
missile damage rarely
cause leaks in an SPF roof.
The damage typically can be
repaired at a later date without
compromising the longterm
performance of the SPF
roofing system.11 One of the
most famous examples is the
New Orleans Superdome. A
severe hailstorm damaged
areas of the SPF roof in
1978. For the next 10 years,
the city debated how best to
repair the damaged roof.
Finally, in 1992, the roof was
repaired and re-coated. However,
prior to the repairs, the
roof never leaked from the
hail damage. (Some leaks
were reported that were
actually caused from bullets fired at the roof during Mardi Gras.)12
SPF Reduces Construction Debris
ORNL also reported, “The need for multiple roofs makes roofing
one of the largest contributors of solid waste.”8 According to the
National Roofing Contractors 1999 Survey, more than 68.5% of the
11.3 billion dollar low slope re-roofing market includes tear-off and
replacement of the existing roof membrane.13 SPF roofing systems
have excellent adhesion to a variety of substrates, including BUR,
modified bitumen, concrete, wood, asphalt shingles, clay tile, and
metal. Since SPF adds little weight and can be applied in various
thicknesses to add slope and fill in low areas, SPF roofing systems
are often used as a recover system over existing roofs without tearoff.
Therefore, the application of SPF roofing systems over existing
roof coverings greatly reduces the amount of construction debris in
our landfills.7
Detail 3
Detail 4
16 • Interface April 2004
So to conclude this section, SPF roofing systems demonstrate
significant sustainable characteristics. SPF roofing systems have a
long life, are renewable, save energy, add durability to buildings,
control moisture in buildings, and contribute very little to the waste
stream. SPF roofing systems greatly reduce tear-offs in many reroofing
projects, which also decreases the amount of materials
entering the waste stream.
SECTION 2: INSULATION AND AIR BARRIER
SYSTEMS
“Environmental control within a building envelope depends on
strong interaction [among] heat, air, and moisture transport collectively.”
In order to control these factors, there must be “effective air
barriers, rain screens, weather barriers, and thermal insulation of
a continuous nature so that gaps do not compromise the climate
control design.”14
“The durability of a material in a building envelope depends on
the outdoor and indoor climate, type of construction, and conditions
of service. A small change in one of these variables may result
in material failure during the first year or a flawless performance
for forty years.”15
The use of SPF systems can significantly affect the durability
and climate control of a building. Three SPF systems are used within
the building envelope: high density (1-1/2 to 2 lb/ft3), low density
(less than 1/2 lb/ft3), and sealant foams. High density SPF is
used when strength, high moisture resistance, and high insulating
value are desired. Low density SPF is used when insulation, air barrier,
and sound control are desired. Sealant foams are used to caulk
around windows, doors, sill plates, and other locations to seal
against unwanted air infiltration.
R-Value
SPF’s aged R-value varies, depending on the formulation, type
of blowing agent used, and type of application. Aged R-values of
SPF used in insulation and roofing applications with a density
ranging from 1-1/2 to 3 lb/ft3 typically range between 6 and 7.5 per
inch. Factors affecting the R-value include: thickness of application
(the thicker the foam the better the aged R-value), and the substrate
and covering systems used (the lower the perm rated covering
and substrate, the higher the aged R-value).15 Low-density (1/2
lb), open-celled SPF typically has a stable, aged R-value ranging
from 3.4 to 3.6 per inch (Chart 2).
METAL EPDM URETHANE FOAM HYPALON®
VALUE ENGINEERED
ROOF COATING SOLUTIONS
TRUCO, INC.
4301 Train Avenue
Cleveland, Ohio 44113
216 / 631-1000
800 / 227- 4569
www.truco-inc.com
NATURE INVENTED
“WATERTIGHT,”
WE JUST
PERFECTED IT!
CAPITAL BLUE CROSS
(IN PROGRESS)
ETERNA-SEAL®
OVER EPDM
SARA LEE
COFFEE & TEA
ETERNA-SEAL®
OVER HYPALON®
MEMORIAL
ELEMENTARY SCHOOL
ETERNA-SEAL®
OVER METAL
SOUTHFIELD
PROPERTIES II LLC
ETERNA-SEAL®
OVER HYPALON®
Chart 2: SPFR value aging curve.
18 • Interface April 2004
In 1997, ORNL performed whole and clear wall testing of SPF
between metal stud walls. Three quarters of an inch of high density
SPF was applied between studs and 1/2″ over the metal studs.
Results confirmed that the use of SPF greatly reduces the thermal
bridging effect of the metal studs.18
By controlling moisture infiltration, SPF also provides greater
durability to buildings. The number one cause of building deterioration
is moisture within the building envelope. Building performance
in hurricanes and other catastrophic events can be
adversely affected by moisture damage.19
Structural Strength
SPF can add structural strength to buildings. Testing conducted
by the National Association of Home Builders Research Center
showed that SPF insulation between wood and steel stud wall panels
increased rack and shear by a factor of 2 to 3 when sprayed onto
gypsum board and vinyl siding and increased racking strength 50%
when sprayed onto OSB. According to the NAHB Research Center,
“During a design racking event (such as a hurricane), there would
be less permanent deformation of wall elements and possibly less
damage to a structure that was braced with SPF filled walls.”20
Providing a continuous air barrier, preventing moisture infiltration
through air leakage, minimizing condensation within the building,
avoiding thermal bridging, resisting heat movement in all
directions, and providing reliable performance under varying climatic
conditions, SPF provides better climate and moisture control.
16 Better climate control saves energy and makes the building
more comfortable. Better moisture control reduces building deterioration,
increasing the life of the building. SPF’s climate control
Typical SPF roof.
Chart 4
Chart 3
April 2004 Interface • 19
attribute enables a downsizing of the heating and cooling equipment
of a building, further reducing energy use. Side-by-side energy
efficiency comparisons have shown up to 40% energy savings by
using SPF over the commonly specified insulation materials.17 The
use of high density SPF within the building can add significant
structural strength, minimizing damage from building movement
and racking events.
Ozone Depletion and Global Warming
There are still some groups that consider SPF harmful to the
environment due to the blowing agents used in the higher density
foams. The following information should dispel that concern.
Before 1992, most high density SPF used CFC 11 as the main
blowing agent. From 1992 to the present, HCFC 141b has been the
main blowing agent used in SPF. HCFC 141b will be phased out in
the next couple of years. The most likely blowing agent candidates
are blends of HFC 245fa, Pentane, or water.
“The HCFCs and HFCs are considered environmentally superior
to CFCs because they are largely destroyed in the lowest region
of the atmosphere. The HFCs do not contain chlorine and have no
potential to deplete ozone. HCFCs, however, do contain chlorine,
but only a small percentage of that chlorine can affect the ozone
layer; this is because most of the HCFCs released at ground level
are destroyed in the lower atmosphere before they reach the
stratospheric ozone layer.”21
The global warming potential of a material is calculated by its
total environmental warming impact (TEWI). The TEWI of a material
is the total effect of the combination of direct (chemical) emissions
and indirect (energy-related) emissions on global warming. In
the case of insulation systems, the direct effect equals the total
greenhouse gases released into the atmosphere. The indirect effect
is calculated by estimating the equivalent carbon dioxide emissions
based on how long the system remains in place before replacement
and the total amount of fuel consumed. Because of the world’s
dependence on fossil fuels for primary energy needs and the predominant
contribution of carbon dioxide to future global warming,
energy efficiency is crucial in minimizing contributions to these
issues.22
SPF conforms to unusual substrate configurations.
• RE-ROOFING • REPAIRS • MAINTENANCE
• NEW CONSTRUCTION • WATERPROOFING
• 24-HR EMERGENCY SERVICE
Oregon • Washington • Since 1922
Oregon Office:
P.O. Box 23819
12650 SW Hall Blvd
Tigard, OR 97281-3819
T: 503-620-5252 • F: 503-684-3310
www.snyderroofing.com
Snyder Roofing, a family owned business, has
been at the forefront of the commercial,
industrial, and
institutional roofing
business in the
Pacific Northwest
since 1922. Their
commitment to
excellence, dedication to high technology
solutions, and reputation for reliability and success
have set them apart as a leader in the commercial
and industrial roofing business.
We’re proud of the
Snyder name. It stands
for expertise, integrity,
and imagination.
Jim King, CEO
CCB # 0000158
Snyder Roofs Stand
Out Above the Rest.
Washington Office:
20203 Broadway Avenue
Snohomish, WA 98296
T: 425-402-1848 • F: 425-398-4444
www.snyderroofing.com
20 • Interface April 2004
From 1980 to 1990, carbon dioxide contributed 55% of greenhouse
gases that affect future global warming. CFC blowing agents
(which were used at that time in SPF insulation) contributed 17%
of greenhouse gases during the same time period. Replacing CFC
blowing agents in foam insulation with HCFCs reduced the global
warming potential of SPF insulations by 92%. SPF’s exceptional
insulation quality reduces the amount of energy required for heating
and cooling, thereby significantly reducing the amount of carbon
dioxide released into the atmosphere.
The global warming potential of a gas is calculated from its
energy absorbing properties over a specified length of time. The
longer it takes for a gas to be purged from the atmosphere, the
worse its global warming potential. It takes more than 500 years for
carbon dioxide emissions to be purged from the atmosphere. Even
after 500 years, 19% of carbon dioxide survives to affect global
warming. Most HCFC 141b and HFC 245fa blowing agents have left
the atmosphere within 10 years.22
While most roofs are replaced within 15 years, the wall insulation
systems typically remain in place until the building is remodeled
or demolished. The longer the insulation system remains in
place, the more reduction to global warming. SPF roofing systems
are not replaced as often, thereby increasing their effectiveness in
reducing global warming. Utilized as an insulation system, SPF’s
ability to provide effective air barriers and control moisture increases
its effectiveness in reducing global warming.
SPF and Energy Costs of Production
Franklin and Associates Ltd.’s study, “Comparative Energy
Evaluation of Plastic Products and Their Alternatives for the
Building and Construction and Transportation Industries,” compares
the total energy requirements for the manufacture of plastic
products to the total energy requirements for the manufacture of
the alternatives. The unique feature of this type of analysis is its
focus on all the major steps in the manufacture of a product, raw
material extraction from the earth, fabrication, and even transport,
rather than a single manufacturing step.23
The study concludes that plastic products in the building and
construction industry use less energy from all sources than the
alternative materials. According to the Franklin and Associates’
study, polyurethane foam insulation saved 3.4 trillion BTUs in
manufacturing energy over fiberglass insulation in 1990. One trillion
BTUs are equivalent to almost 170,000 barrels of oil and one
billion cubic feet of natural gas.
As mentioned earlier, SPF helps reduce tear-off debris in roofing
applications. SPF’s on-site application process generates very
little debris and waste. A typical 10,000 square foot roofing project
produces less than 1/2 cubic yard of scrap SPF, tape, and plastic
(used for masking) and from one pint to three gallons of waste solvent
(depending on the type of protective covering used). Compare
this to the typical 10,000-square-foot re-roofing project that produces
more than 10 yards of construction debris from tear-off and
application waste. At the present time, so little scrap SPF is produced
that recycling of the material is not practical.9■
REFERENCES
1. Kashiwagi, Dean, PhD, PE, 1996 Roofing Contractors/
Systems Performance Information.
2. Dupuis, René M., PhD, PE, Structural Research, Inc., “A
Field and Laboratory Assessment of Sprayed Polyurethane
Foam-Based Roof Systems,” conducted for the National
Roofing Foundation.
3. Cohen, Sam, PE, “Texas A&M’s SPF Roofing Experience,”
Spray Foam 1994.
4. Bretz, S., H. Akbari, A. Resenfeld, and H. Taha, “Implementation
of Solar Reflective Surfaces: Materials and Utility
Programs,” Lawrence Berkeley Laboratory, University of
California, Berkeley, California, June 1992.
5. Downey, Patrick, “Energy Efficient Roof Design,” Interface,
May 1995.
6. Watts, Mike, CSI, CDT, “Thermal Conductivity in Mechanically
Fastened Roof Systems,” Interface, May 1996.
7. Knowles, Mason, “Sustainability Characteristics of SPF
Roofing Systems,” 1996 Low-Slope Sustainable Roofing
Conference, Oak Ridge National Laboratories.
8. “Building Thermal Envelope Systems and Materials,”
Update, April 1996, Envelope Research Center, Oak Ridge
SPF helped to seal repairs made to this existing roof.
Roof mounted HVAC units should be raised and curbed, but
typically don’t require additional counterflashing.
April 2004 Interface • 21
National Laboratories.
9. Knowles, Mason, “Energy Conservation and Thermal Envelope
Design Using Polyurethanes, Spray Polyurethane
Foam,” Presented at ACSA Construction Materials and
Technology Institute, 1996, University of California at
Berkeley, California.
10. Spray Polyurethane Foam Roof Insulation with Protective
Coatings for Use in Recover Roof Construction and New
Construction over Structural Concrete Roof Decks, Factory
Mutual 4470 Test, 1996.
11. Fricklas, Richard L., “An Update on Hail and Wind
Considerations,” SPFA Newsletter, May, 2000.
12. “SPF – Tomorrow’s Roof Today,” SPFA brochure, AY 129.
13. “1999 NRCA Market Survey,” Professional Roofing, March,
2000.
14. Bomberg, M., PhD., PE, and M.K. Kumaran, PhD, PE,
“Building Envelope and Environmental Control,”
Construction Practice, 1994.
15. Bomberg, M., PhD, PE, and J. Listriburek, PE, Spray Polyurethane
Foam in External Envelopes of Buildings, 1998.
16. Bomberg, M., PhD, PE, and R. Alumbaugh, PhD, PE, “Factors
Affecting the Field Performance of Spray Applied
Thermal Insulating Foams,” presented at Spray Foam ’93.
17. Knowles, Mason, “Energy Conservation and Thermal
Envelope Design Using Polyurethanes,” presented at ACSA
Construction Materials and Technology Institute, 1996,
University of California.
18. Kosny, Jan, André Desjarlais, and Jeff Christian, “Whole
Wall Rating/Label for Metal Stud Wall Systems with Sprayed
Polyurethane Foam (SPF); Steady State Thermal Analysis,”
1998, Oak Ridge National Laboratory, Buildings Technology
Center.
19. Tenwolde, Anton, BETEC Symposium, Air Barriers 1, 1996.
20. SPF Wall Panel Performance Testing, 1992 and 1996,
National Association of Homebuilders Research Center,
Berkeley, CA.
21. Atmospheric Chlorine: CFCs and Alternative Fluorocarbon,
Alternative Fluorocarbons Environmental Acceptability
Study, U. S. Department of Energy, 1999.
Page 21
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22 • Interface April 2004
22. Energy and Global Warming Impacts of CFC Alternative
Technologies, Executive Summary, Alternative
Fluorocarbons Environmental Acceptability Study,
U.S. Department of Energy, 1999.
23. Franklin Associates, Ltd., Comparative Energy
Evaluation of Plastic Products and Their Alternatives for
the Building and Construction and Transportation
Industries, Final Report, prepared for The Society of
The Plastics Industry, 1991.
Page 22
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Coming from Bill
Remove this Border
Mason Knowles is the
Executive Director of the Spray
Polyurethane Foam Alliance
(SPFA) of the American Plastics
Council (APC) and recently
served as the Technical Director
of the American Plastics Council
on building and construction
issues. He is a member of ASTM
and chairman of D O8.06 Sub-
Committee on Spray Polyurethane
Foam Roofing Systems
and ASTM Task Group Chairman for the revision of
ASTM C-1029, Standard Specification for Spray Applied
Cellular Polyurethane Insulation. Knowles has been in
the polyurethane foam industry 33 years and has an
extensive background in SPF roofing, cold storage,
industrial, commercial, and residential insulation applications,
and has written and/or co-authored dozens of
technical papers and articles on plastics and SPF.
ABOUT THE AUTHOR
MASON KNOWLES
All of the buildings
in the U.S. consume
more than twice as
much energy as all
of the cars in the
country (when you
consider, in BTUs, the
total embodied energy
it takes to construct
and operate them). They
emit twice the amount of carbon
dioxide as cars – which make them the leading humaninduced
cause of global warming. Buildings also consume
80% of the nation’s drinking water and 2 million
acres of forests and farmland each year.
— GRIST MAGAZINE
ENERGY CONSUMPTION
OF BUILDINGS