a small gap left between the sheathing panels,
often as large as 1/8 to 1/4 inch wide. This small
space can allow water to enter the home if the
external roof shingles or tiles are compromised.
The external roof shingles or tiles are typically the
first part of a roof system to fail in hurricane-force
winds. With the spray foam protecting these gaps
as a secondary barrier, water cannot penetrate the
roof if the shingles are blown away.
In a recent interview with Jason Hoerter, Sr.
Product Manager and building science engineer
with NCFI Polyurethanes, we learned about NCFI’s
focus on this market sector and the company’s
recent accomplishments with third party qualified
testing and Florida Product Approvals for their
InsulStar® product line.
Hoerter mentions, ”The 2007 University of
Florida tests were substantial in their ability to
prove concept for spray foam as a wind destruction
mitigation product solution. But the bar has been
raised significantly higher now that we have actual
third party qualified test results and a Product
Approval from the state of Florida for InsulStar®
According to NCFI literature, their product
complies with the requirements for use both inside
and outside High Velocity Hurricane Zones (HVHZ)
as listed in their Florida Product Approval #9975.
” We worked long hours with the University of
Florida to get that initial Florida Product Approval.
They make sure products are safe and work for
the state’s homeowners. Since then, we’ve tested
our products at a Miami-Dade
approved third-party laboratory
and are expecting a Miami-Dade
NOA approval on InsulStar® in the
very near future,” Hoerter said.
There are several
application techniques that NCFI
promotes for spray foam usage in
wind destruction mitigation that
can also accomplish insulation and
potential energy savings as well.
The first Level- 1 is simply
for wind destruction mitigation
and involves the application of
the spray foam adhesive ”fillet”
at the junction of the roof wood
sheathing and rafter/truss.
The second Level- 2
maintains the traditional vented
attic assembly, follows all the
Level - 1 steps for wind destruction
mitigation, but also includes the
application of 1/2 to 1 inch of foam across all of
the roof sheathing. This thin application foam
provides just enough insulation to keep the attic
temperature significantly lower than normal in
the hot southern climates. Reduction of the hot
temperature in the attic space can have positive
results on the cooling efficiency of the home
and moisture/condensation issues with HVAC
equipment in that space.
The third and most energy efficient, Level- 3
method includes all of the Level- 1 wind destruction
mitigation application, but instead of maintaining
a vented attic assembly, a full covering of several
inches of sprayed polyurethane foam is applied
to the entire underside of the roof area covering
all vents and completely sealing the attic space to
create a much more energy efficient unvented attic
Extensive testing by universities, SPF
manufacturers and third party groups now
demonstrate that closed-cell insulating spray-
foam adhesive provides solid structural benefits
to the home, insulation value, and water barrier
The state of Florida requires insurance
companies to offer Florida homeowner’s discounts
or credits for construction techniques that reduce
damage and loss in windstorms. The wind portion
of their total homeowners insurance premium can
be a substantial amount and the savings from
installing spray foam insulation are generally 60 to
80 percent of the windstorm premium and 25 and
60 percent of the total annual premium.
Savings tend to be greater for homes built
before 2002 and greatest for homes close to
the coast. Every insurance company’s discount
structure is different, but some homeowners
located near the coast report premiums reduced
by more than half after application of closed cell
spray foam insulation in the attic, bonded to the
underside of the roof sheathing.
Photo Left illustrates gaps in the roof sheathing where shinlges
have been blow off the house in the hurricane. This is a major
source of water leakage.