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Home | Building Codes | The Battle Against Severe Weather Disasters: Closed-Cell Spray Polyurethane Foam in Hurricane Zones
Spray Foam Magazine - Severe Weather - Closed Cell Spray Foam

The Battle Against Severe Weather Disasters: Closed-Cell Spray Polyurethane Foam in Hurricane Zones

This issue focuses on closed-cell spray foam insulation, adhesives, and commercial, lowslope SPF roofing. These products when used correctly and properly installed have proven themselves to do far more than insulate your building and cover your roof.


Closed-cell spray foam has undergone extensive product testing in a variety of applications and building solutions from trade associations, government agencies, third-party labs like Underwriter’s Laboratory (UL), and FM Global (FM), SPF industry suppliers and lastly, Mother Nature herself.


The results have been stellar in SPF’s ability to reduce wind uplift on roofing systems both inside the home and outside on the commercial building roof. Closed-cell spray foam has been proven to increase the strength of a building. NAHB Research demonstrated SPF filled walls could add from 75% to 200% racking strength to walls of OSB, plywood, light gauge metal, vinyl siding or gypsum board.

The University of Florida, Clemson University, and numerous SPF suppliers have demonstrated that spray foam applied as an adhesive bead, or fillet, to the underside of the roof joist and sheathing can significantly enhance the wind uplift strength of your home two to three times greater than nails alone. The state of Florida has even issued Product Approvals, and mandated that insurance companies provide rebates when these preventative systems have been installed


Some SPF commercial roofing assemblies have achieved negative uplift (pressure created on a roof as high velocity wind passes across the surface) ratings as high as -495 lbs. per square foot (PSF) uplift capability. This translates to being able to withstand roughly the strongest Category-5 hurricane negative uplift pressures. Traditional modified bitumen and built-up gravel roof systems are rated at 1/4 (or less) that negative uplift pressure rating. SPF roofs have not only performed well in the lab, but in the real world in major hurricanes and high wind events.


SPF is most commonly used as insulation in walls, crawl spaces, and in unvented attics under the roof sheathing. There are two major types of SPF used in residential building envelope insulation; closed-cell spray foam and open-cell spray foam. Both work well for energy efficiency, but only closed-cell spray foam has the advantage to add structural integrity and compressive strength to the building envelope. Closed-cell spray foam also is a FEMA rated flood resistant material, making it again ideal in severe weather and water / flood damage prone areas. This article will focus on the attributes of closed-cell SPF. On the commercial building side of things, spray foam is used again as insulation for the building envelope, but its real advantage to large buildings, both in severe weather climates and others, is as a commercial roofing material. SPF is spray-applied and automatically self-flashing due to its physical characteristics. It has been found to be durable, highly energy efficient and relatively easy to maintain as a roof systems. It is sustainable, which makes it a green product, and it stands up to torrential weather better than many other alternative roofing systems and products.



Sprayed polyurethane foam and closed-cell plastic foams are the only materials that FEMA classifies as acceptable flood damage resistant insulation materials for floors, walls and ceilings in its building design criteria for special flood hazard areas (SFHAs).


We have assembled several articles on monolithic dome construction because of their brute strength and rapidly growing adoption rate in tornado prone areas across the Southeast and Midwest United States. Monolithic Domes can sustain winds of up to 300 miles per hour (100 more than required by FEMA). In contrast, any wind gust of more than 50 miles per hour, sustained for at least three seconds, can cause damage to a manufactured home.

Not only are Monolithic Domes less expensive to build than traditional tornado shelters, but they also are extremely energy efficient, costing as much as 50 percent less to heat and cool than other structures of the same size. A quick visit to The Monolithic Dome Institute’s (MDI) website, or a search in YouTube will provide an amazing tour of these structures, not only used as municipal hurricane shelters, but as quaint and luxurious homes as well. Monolithic Domes meet FEMA standards for ”near-absolute protection” both because of their shape and the materials used in their construction. Concrete in a curved shape reinforced with steel rebar is stronger than any other type of building, according to Arnold Wilson, professor emeritus of civil engineering at Brigham Young University and a consulting engineer for MDI.

But what about the spray foam? Closed-cell spray foam’s role in the dome comes mainly as a superior insulation system. However, the additional structural characteristics of closed-cell SPF are what allow the dome builders to actually ”build” the structure. Therefore, SPF is as integral in the dome’s construction process as it is in its ability to make the building structure highly energy efficient. This further demonstrates closed-cell SPF’s capability beyond a simple insulation and roof covering material. SPF is also used to lift floors, level ground, and seal up old mine shafts and underground tanks. We have compiled several articles that will demonstrate the wide application range of SPF. For those readers inside the SPF industry, you will notice that not all the content is new, but it is all-relevant to the severe weather capabilities of closed-cell spray polyurethane foam. The articles and job profiles in this issue were specifically selected to bring all of the severe weather benefits into one handy reference.


Closed-cell spray foam is being used as a tenacious construction adhesive. SPF suppliers are reporting that they are receiving many different levels of third party test approval for use in wind mitigation in the state of Florida. A few of these test credentials include Florida Building Code Performance Standards, Florida Product Approvals, and even Miami-Dade Notice of Acceptance (NOA).

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