In terms of extreme weather disasters, hurricanes typically rank at the top of the scale of damage and risk to loss of life, property, businesses and homes. High winds, embedded tornadoes, abnormal amounts of precipitation, major flooding and coastal surges, along with extensive areas, thousands of square miles, of the various storm’s coverage, make hurricanes a major threat to millions of households and business.

An initial indicator of a hurricane’s danger and risk is wind speed. However, the aftermaths of flooding, power outages, distribution and travel restrictions, lack of adequate shelter over widespread areas, gasoline and food shortages and greater danger to young children or elderly from the typically high heat during hurricane season, often pose greater risks than the initial wind speed.

Closed cell spray foam cures to a very dense and rigid state, acting not only as energy saving insulation for your home, but It acts as a kind of glue that strengthens the surface to which it is applied by 300%, using medium density foam, and double that amount using the new high density HFO roofing foams; see chart in increasing hazard section. Thus, your roof and walls are much more likely to remain intact in a severe weather event such as a hurricane.

When it comes to your home’s basement or crawlspace, having insulation that rejects bulk water for up to 72 hours can go a long way in helping to prevent significant damage that hurricanes sometimes cause.

Closed cell is the optimal choice to effectively insulate subfloors in flood zones. Not only is it waterproof, it also increases the strength of the building to which it is applied. As a vapor barrier, closed cell creates a seal that prevents humid air from moving through the insulation and into your home, keeping humidity and moisture out.

Spray Foam’s Hurricane, Flood & Wind Resistance Performance in Commercial Facilities By Maxime Duzyk May 11, 2021. See FEMA updates as of June 2024

The increasing number and intensity of hurricanes and storms in the United States is not only cause for general safety concern but is top-of-mind for builders, contractors and facility owners who have witnessed the damage that may be incurred to commercial structures. Stanford University researchers recently attributed a $75 billion price tag specifically to the flood damage incurred in the U.S. over the past three decades, caused by intensifying rainfall driven by climate change. Another report by reinsurance company Munich Re determined that in 2020 the world’s six most expensive disasters occurred in the U.S., the worst of which was Hurricane Laura.

Commercial facilities are in fact vulnerable to serious storms and inclement weather. First Street Foundation, the non-profit research and technology group, asserts that more than 14 million properties across the United States are susceptible to flood damage. Luckily building material innovations have resulted in options that, when applied properly, can assist in protecting commercial facilities from the severe weather events bound to grow in frequency. Closed cell spray polyurethane foam (SPF) is one such material. When applied by a seamless, contiguous manner in walls, ceilings, floors and on the roof, closed cell SPF protects the structure from serious, costly damage.

Water Resistive Barrier & Flood Resistance

Closed cell spray foam is ideal for continuous insulation applications in commercial structures and can be used in both interior and exterior applications where it can essentially replace commonly utilized rigid XPS and PIR foam boards. The material boasts low water absorption as well as resistance to mold, as demonstrated with ASTM C1338. Closed cell spray foam excels as a water resistive barrier on exterior applications and is tested in accordance with ASTM E2357 with a pressure up to 300 Pa for Air Barrier Assemblies which included the ASTM E331 (AC71) Water Penetration Testing. The result was no leakage through the spray foam.

When applied in walls, ceilings and floors, FEMA names it a Class 5 material, the highest classification for products indicating strong resistant to floodwater damage. Class 5 materials do not require special waterproofing protection, can survive wetting and drying and may be successfully cleaned after a flood to render them free of most harmful pollutants. In order for FEMA to consider a material to be flood-resistant, it must be able to withstand direct contact with floodwater for an extended period (72 hours) of time.

As a Class 5 solution, closed cell spray foam provides both time and money savings for owners of commercial structures which have endured flood conditions and may be applied as cavity insulation or as continuous insulation in commercial structures and still qualify as a Class 5 material. It is the only cavity insulation approved by FEMA with this highest floodwater resistance. When applied under slab as insulation, closed cell spray foam is also flood resistant.

 Structural Strength and Wind Resistance

The application of closed cell spray polyurethane foam in above grade walls can also increase the structural strength of buildings and assist with wind resistance. The degree of hardening depends primarily on the strength of the building to begin with. For example, an I-beam modular constructed metal building with a 22-gauge metal panel will benefit significantly less from an interior application of closed cell spray polyurethane foam than a post-frame constructed building with 29-gauge corrugated metal panels will. When installed, closed cell SPF essentially glues the assembly together, reduces the potential for movement and adds a tensile strength average ranging from 40 psi to 70 psi and compressive strength of 40-80 psi.

The Spray Polyurethane Foam Alliance conducted racking performance tests in 1992 and 1996 and at Architectural Testing, Inc. in York, PA in 2007 demonstrating that medium density closed cell SPF, installed at 2.0 pounds per cubic foot, increases racking strength by 70% to 200% in wall assemblies sheathed with oriented strand board (OSB), plywood, gypsum wallboard, vinyl siding and polyiso board. The research proved closed cell SPF significantly increased rack and shear strength in both wood and metal construction. Installed SPF also increases the strength of weaker substrates such as gypsum drywall, vinyl siding and polyiso foam insulation at a much greater percentage than stronger substrates such as OSB and plywood. Notably, special bracing for wind resistance is not required for strengthening purposes when using closed cell spray foam in walls. Since that time closed cell spray foam formulations have been upgraded to HFO blends which have even greater compressive strength (40-80 psi) and very low CWP of 1; which is the same as CO₂.

In addition, the racking strength increase is not just a spot measure but applies to the whole structure. It is applied in a seamless fashion with no breaks, gaps in coverage or flex points. Thus, the structure is resistance to the shearing and multidirectional forces exerted during extreme weather conditions of hurricanes, tornados and earthquakes. 

Roofing & Wind Uplift

Spray polyurethane foam roofing, a denser closed cell option from 2.5 to 3.5 pounds/ft³, is also an ideal solution for commercial structures located in hurricane prone regions such as the Southeast, Gulf Coast, East and West Coast and Puerto Rico. The material’s adhesion qualities make it particularly ideal where severe weather cycling, storms, wind, hail and other conditions frequently cause damage. As a roofing material, spray foam forms a durable, monolithic membrane over the roof and offers a compressive strength of approximately 40 to 80 pounds per square inch, depending on its density. See chart in increasing hazard section. It also changes little with time and, when properly maintained has an indefinite life span.

Spray foam roofing increases wind uplift resistance when installed to the roof substrate and, when applied to concrete, wind uplift protection is even stronger. The material also resists peeling failure, which is a result of wind pulling flashings and copings away from a roof’s edges, which can ultimately lead to devastating damage to the structure.

Current high-performance spray foams demonstrate wind uplift resistance by meeting the High Velocity Hurricane Zone (HVHZ) criteria of the Florida Building Code. Notably, the material’s ability to withstand leaks due to hail is also unsurpassed.

The National Institute of Standards and Technology reviewed roof damage following Hurricane Katrina and discovered that buildings roofed with spray foam performed well without blow-off of the SPF or damage to flashings. The 2006 report found only one of the examined SPF roofs incurred notable damage and concluded that spray foam kept the roofs intact, prevented moisture from entering the buildings, and protected the structures from hail and debris.

References

1. CNBC, Climate Change has Cost the U.S. Billions of Dollars in Flood Damage, Study Finds, https://www.cnbc.com/2021/01/11/climate-change-has-cost-the-us-billions-of-dollars-in-flood-damage.html
2. First Street Foundation, The First National Flood Risk Assessment: Defining America’s Growing Risk, http://assets.firststreet.org/uploads/2020/06/first_street_foundation__first_national_flood_risk_assessment.pdf
3. FEMA, Flood Damage-Resistant Materials Requirements for Buildings Located in Special Flood Hazard Areas in Accordance with the National Flood Insurance Program, Technical Bulletin 2, August 2008
4. Honeywell, Insulation and Waterproofing for Metal Buildings and Metal Roof Systems: The Case for Using Better Insulation and Waterproofing Technologies in Metal Roof Systems and Metal Buildings
5. Architectural Testing, Performance Test Report Rendered to Spray Polyurethane Foam Alliance, Project: Racking Load Tests, 2007.
6. National Institute of Standards and Technology, Performance of Physical Structures in Hurricane Katrina and Hurricane Rita: A Reconnaissance Report, 2006

Increasing Hazard

Jeremy Greenberg, director of the operations division in FEMA’s Response Directorate, has stated “The duration, frequency and intensity of the hazards is increasing over time, It’s becoming a little more commonplace that this map looks like this, and we’ve got a variety of hazards.”

Disasters in the United States used to follow a fairly predictable pattern. Winter brought snow; spring brought floods and the summer and early fall delivered hurricanes, with hopefully some downtime before the cycle would start again. Now, those seasonal shifts are becoming less meaningful. “A snowstorm in the Rockies in the winter is very normal,” he said. “A tornado in Alabama in the winter is not.” Greenberg sees a silver lining in the relentless parade of severe weather: It can grab the attention of Americans, helping them understand that the world is changing around them and they need to be ready.

“The hazards are real,” Greenberg said. c.2024 The New York Times Company

Closed cell spray polyurethane foam (SPF), when applied in walls, ceilings, floors and on the roof, ranging in densities from 2.0 to 3.5 pounds per cubic foot (PCF), protects the structure from serious and costly damage (see following ratings and wind speed charts). It can alleviate concerns of builders, contractors and facility owners due to the increasing number and intensity of severe storms in the United States and the resulting damage that may be incurred to commercial and residential structures.

MAINTAINING DESIRED INTERIOR BUILDING ENVIRONMENT

Factors to consider – Structural Integrity – Air seal – Insulation

In order to establish safe and comfortable interior living and working conditions, it is necessary to understand the inter-relationships of structural integrity, energy transfer, material thermal efficiency and maintenance of the desired environment. The importance of maintaining a livable environment, especially after an extreme weather event, cannot be overstated

STRUCTURAL INTEGRITY

All structures are subject to change over time due to the following:

1. Severe weather – Earthquakes, Fire, Tornados, Hurricanes, Flooding.
2. Shifts in external climate – Warming, Cooling, Drought and Abnormal Fluctuations.
3. Gradual changes in underlying soil or foundation – Settling, Subsidence and other foundational shifts.

AIR SEALING – INSULATION

Any of the above can weaken or destroy the initial static integrity of the structure and result in subpar or undesirable conditions for the occupants and or material and resulting in additional costs to repair, replace or abandon them. The purpose of this article is to discuss interior maintenance of desired conditions in a static external environment and specifically the relationship between Air Sealing and Insulation.

The underlying principles of these factors are; energy and temperature transfer between external and internal conditions, thermal efficiency of materials and the blocking or insulating of energy and or heat transfer conditions.

In other words; if its warm outside you want it cool inside or the reverse, cold outside and warm inside, and you want to consume the least amount of energy to accomplish it.

ENERGY TRANSFER

Thermal Engineering 2019-05-22 by Nick Connor

Heat transfer is usually classified into various mechanisms, such as:

1. Heat Conduction.Heat conduction, also called diffusion, occurs within a body or between two bodies in contact. It is the direct microscopic exchange of kinetic energy of particles through the boundary between two systems when an object is at a different temperature from another body or its surroundings. Note: a closed building prevents heat or cold transfer by this means
2. Heat Convection.Heat convection depends on motion of mass from one region of space to another. In the absence of blocking or insulation interior temperatures will equalize to external ambient temperatures. Air sealing and insulation is necessary to mitigate this condition.
3. Thermal Radiation.Heat is transferred by electromagnetic radiation, such as sunshine, with no need for matter to be present in the space between bodies; i.e., the exterior of a building or material will be hotter than the ambient air. Note: reflective material will prevent radiant heat transfer.

Polyurethane foam insulation (SPF) is available in closed-cell and open-cell formulas and is a superior insulating material. Typical thermal conductivity values for polyurethane foams are between 0.022 and 0.035W/m∙K.

Note:

Closed-Cell SPF (ccSPF) – At 2-lbs per cubic foot or more, closed-cell SPF is. at least, four times denser than open-cell foam. In compression closed-cell is ten to 20 times stronger than open-cell and seven to fifteen times stronger in tension. Closed-cell SPF is, in fact, utilized as structural adhesive at many modular-housing factories to glue gypsum board to wall studs and ceiling joists. Studies at the University of Florida and elsewhere have documented the structural advantage of using ccSPF to glue roof decking to trusses in hurricane-prone areas. Similarly studies by Consortium for Advanced Residential Buildings, Steven Winter Associate s, Inc. have found that the racking strength of frame walls is substantially increased when ccSPF is used in the frame cavities: an advantage for seismic and hurricane zone construction. The closed cell version has superior insulation ratings and is the preferred insulating material for maintaining structural rigidity in a building and offers excellent protection for most of the external hazards previously mentioned. In addition, it provides air and vapor barrier, is not damaged by water or flooding conditions and is impervious to mold, rodents and insect damage.

A comparison of insulating materials follows.

After reaching 94% efficiency, the incremental gains in efficiency or insulating properties are small compared to the additional material required. The main advantage for additional material for closed cell foam is the increase in racking strength ccSPF, provides. Densities can range from 2-4 lbs./cu ft. and higher, depending on the desired structural strength.

Energy requirements

Closed-cell foam can produce energy efficient ratings in excess of 95%, with 2.5 inches of foam. In addition, closed-cell foam is highly water and flood resistant and does not lose  insulating and structural properties if wet. Several studies done at Texas A&M University and a school district in Southern Texas indicate that the energy savings alone paid for the roofing system and all the other benefits such as the following were essentially included:

1. Storm damage resistant along with easy repair since damage, if any is localized.
2. Minimal maintenance.
3. Stronger more sustainable buildings. Especially important in areas of extreme weather
4. Year round comfort and control of interior environment.
5. Roof contouring to eliminate drainage issues and water ponding.
6. Life of the roofing system is indefinite as it easily renewed with cleaning and/or additional coatings to prevent weathering damage to roof.
7. 5-30 year renewable warranties available.

Our GreenSeal 2.0 to 3.5 products are the best solution to strengthen, protect and insulate your roof and walls from extreme weather conditions in any area of the US. Free inspection available upon request. Closed-cell foams do require specialized equipment and professional installation for proper application and performance.