Sprayed polyurethane foam roof resists wind
These two buildings in Puerto Rico
are located just a few yards apart, so they both received
the same degree of wind force when Hurricane Hugo stormed
over the island. The building on the left received major damage
as wind uplift ripped off a portion of the roof. The building
on the right has a sprayed polyurethane foam roof which held
tight. There was no peeling, penetration or water leakage.
Polyurethane foam is self-flashing--it forms a seal that grips
the building wall and roof-mounted equipment so there are
no edges for the wind to lift up and peel away.
Life, Limbs and property when disaster strikes
- A sealed
envelope of protection from destructive winds
costly water damage
church survived the tornado that cut a path of destruction
through Plainfield, Illinois. The building was completely
covered in sprayed polyurethane foam. There was repairable
missile damage to the exterior surface, yet the sealed
polyurethane foam helped to strengthen the building and
resist uplift from the high-force winds. Because polyurethane
foam is spray-applied, it can conform to any shape and
provide a sealed envelope of protection.
vs Hurricane Andrew
SPF roofing holds
it together during hurricane-force storms
Ten years ago, Hurricane Andrew wrought unprecedented
economic devastation on the northwestern Bahamas, the southern
Florida peninsula and south central Louisiana. According to
the National Hurricane Center, the hurricane caused more than
$26 billion damage in the United States. Before Sept. 11,
Hurricane Andrew was the most expensive disaster in U.S. history.
The insurance industry identifies roofing as
the primary contributor to disaster-related insured losses.
The roof and exterior glass are the most vulnerable parts
of the building envelope in any wind event. Because a damaged
roof can expose the building’s interior — and its inhabitants
— to the storm’s wrath, the total cost of a roof blow-off
can rise as quickly as the storm’s own momentum.
Since Andrew’s devastation, many materials manufacturers
and members of the roofing industry, along with members of
the insurance industry, code officials, architects and consultants,
have invested countless dollars and hours identifying ways
to mitigate the damage caused by roof failure during wind
The reason for roof failure can often be found
in the very design of membrane roof systems. Wind often grabs
the edge flashing or coping and peels back portions of the
In comparison, spray polyurethane foam has gained
recognition with industry experts for its ability to withstand
high wind uplift and blow-off because its smooth, continuous
surface grips the deck and walls. It offers superior adhesion
with no need for fasteners and there are no joints or edges
for the wind to grab onto. Lightweight yet rigid, it provides
extra strength to help the roof stand up to the forces of
“SPF has tenacious adhesion and there’s no way
it will ever blow off,” says Richard Fricklas, founding father
and former technical director of the Roofing Industry Educational
Institute. “It sticks to anything with very high pull-off
strength. The minimum strength of SPF would be about 10 pounds
per square inch and most blow-offs concern pounds per square
foot. Even if the blow-off strength was only 1 pound per square
inch, by the time you multiply it by 144 square inches in
a square foot, that would still be 144 pounds per square foot
of wind uplift resistance.”
Hurricane Andrew struck southern Dade County, Fla., especially
hard, with violent winds characteristic of a Category 4 hurricane
on the Saffir/Simpson Hurricane Scale. In Dade County alone,
the forces of Andrew resulted in 15 deaths and up to 250,000
people were left temporarily homeless. An additional 25 lives
were lost in Dade County from the indirect effects of Andrew.
When it was over, Thomas L. Smith of TLSmith
Consulting, and then research director for the National Roofing
Contractors Association, went to Florida to see first-hand
how SPF had weathered the storm.
“Two things stood out in my mind after my field
studies — one was SPF’s adhesion and the other its ability
to accommodate wind-born debris or ‘missiles,’” Smith reports.
“A missile will tear into or gouge out the foam, but the roof
will not leak. Typically there are a lot of missiles flying
around during a hurricane, so that’s a significant advantage.”
In his published report of his findings post-Andrew,
Smith provides a detailed assessment of the wind performance
of 11 SPF roofs. Three of the buildings were in areas of very
high winds, one in an area of high winds and seven in areas
of moderately high winds.
Two of the three roofs in the very high wind
zones were SPF over old BUR; the third was SPF over thin-shell
concrete. Two of the three roofs sustained minor damage from
missiles. One of the SPF-over-BUR roofs experienced peeling
that did not progress beyond an area of missile impact.
“Often foam is applied over existing roof coverings
and I did see a number of buildings in South Florida where
this was the case,” says Smith. “If the underlying roof is
weak and it lifts up, it will take the SPF with it. But it
appeared to me, although it’s difficult to quantify, that
the foam acted as a stiffener, so when the original roof lifted
up the failure did not propagate as far into the field of
the roof. You might have a corner peeled back, but the corner
area would be limited because of the stiffening influence
of the foam. Had the foam not been applied there, I think
the roof failure would’ve been much larger. I feel very strongly
about that, but it is very hard to quantify.”
Other buildings with traditional roofing systems
in a 200-foot radius surrounding the SPF-over-BUR roof that
peeled suffered significant damage, including gable-end wall
failure and collapsed trusses, as well as blown-off sheathing
panels and asphalt shingles. One building had reportedly had
its BUR blown off.
Smith says that if SPF is going to fail during
a wind event, it is because the surface it has been applied
to has failed. “Typically, the foam is not going to lift unless
whatever it is sprayed to lifts,” he says. “If the deck itself
is not adequately attached, everything above it could just
come off the supporting joists or beams, so that would be
one failure mode. It could also fail if an element between
the deck and the foam doesn’t have good adhesion or if the
SPF is applied to an existing membrane that is not adequately
TRACTOR DIVISION DEPOT
When Ford's corporate
facilities people approved a new roof for the firm's Latham,
NY Tractor Division depot, they did so to solve a long-term
problem resulting from long-term deterioration of the original
tar-and-gravel built-up roof.
What they got, in addition to the ultimate solution
to that leakage problem, was an energy-saving system that
in effect would help pay for the new roof over a period of
The 104,000 sq. ft. building is heated by natural
gas. After installation of the GE silicone roof in October
1977, an analysis of natural gas use indicated 16% reduction
in 1978, attributed to the new roof.
According to roof Plant Manager, Lew Phillips,
the General Electric Company's silicone roof system was selected
after evaluation of several elastomeric membrane systems,
because it promised singular advantages in terms of life,
ease and speed of application and water resistance.
"...a silicone roof
system was selected...because it promised singular advantages
in terms of works life, ease and speed off application, and
"What we didn't count on," said Phillips, "were
the unbelievable fuel economies we realized once the new roof
was in place."
These economies have resulted from the unique
design of the General Electric roof system which, in this
case, decreased the topside's U factor. After thorough cleaning
and spot repair at Ford's existing built-up-roof, urethane
foam was spray-coated on the old surface to a depth of 1".
Two coats of weather-resistant silicone rubber were then sprayed
on the urethane base, forming a tight homogeneous shield that
resists not only moisture penetration, but the deteriorating
effects of ultra-violet as well.
"General Electric's Qualified Applicator,
S.D. Carruthers Sons, Inc., got the total job done -- that's
104,000 sq. ft. of roof -- in just four days, once surface
preparation was complete, " added Phillips. "Facility
maintenance has been reduced because there are no more leakage
problems and the place is much cooler in summer. What
more can you ask?
Information courtesy General Electric Co., Silicone Products
Division, Waterford, NY 12188
Ford Motor Company
Energy Shield, Inc.
138 W. Pike Street Pontiac, Michigan 48341-1747
14425 Sheldon Road
Plymouth, MI 48170
April 27, 1994
RE: Polyurethane Sprayfoam
Re-Roofing by Energy Shield, Inc.
To Whom it may concern:
we elected to re-roof our Sheldon Road plant and administration
building in Plymouth, Michigan, and Energy Shield
was selected to be the contractor by competitive bidding.
The scope of the work involved installing a new sprayfoam
roof to approximately 900,000 square feet of roof
area at a total cost to us of in excess of $2,000,000.
Additional building insulation work was done in 1991
and 1992 by applying sprayfoam to selected wall areas.
of the work was completed in a timely fashion and
with good workmanship. We are especially pleased with
the trouble-free performance of the new sprayfoam
roof system and the dependable follow-up service provided
by Energy Shield.
to the application of the sprayfoam roofing system
our plant had a 25 year old "BUR Roof System"
and we were spending approximately $80,000 annually
doing small repairs to the existing roof. In addition,
the areas above our aluminum radiator furnaces were
experiencing extreme cold and hot spots which was
causing as much as 6" to 8" of movement
of the roofing materials in different directions and
this caused many leaks.
sprayfoam roof system can be applied directly to old
BUR systems and in most cases, such as ours was, total
tearoff of the BUR and can be eliminated with a moisture
study of the roof so as to remove only the wet areas.
Thus the substantial costs of total roof tear-off
and disposal can be eliminated. Another benefit of
the sprayfoam system that we noticed was the reduction
in our energy consumption. At the Sheldon Road Plant,
we realized a decrease in our energy bills from $876,000
annually to about $412,000.
very satisfied with our sprayfoam roof and haven't
experienced any problems or maintenance costs since
the installation. It is a cost effective way to re-roof
and insulate your building.
M. M. Forester, Plant
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Information courtesy General Electric Co., Silicone Products
Division, Waterford, NY 12188