No Place Like Foam--Using SPF to protect facilities from hurricanes and floods
Global warming poses serious consequences to the Earth, its inhabitants, and, consequently, the built environment. As the globe continues to warm, hurricanes, storms, and severe weather patterns grow in intensity. In fact, some of the most damage-inducing hurricanes have occurred within the past several years. In a snapshot of some of the recent storms, 2017 delivered Hurricane Harvey, whose rainfall and cyclone destruction reigned over Texas, Louisiana, and the Tennessee and Ohio Valleys. Hurricane Florence, in 2018, caused monumental damage and deaths in the Florida panhandle and the Carolinas. And, 2021’s Hurricane Ida rendered one million people in Louisiana without power1 before bringing catastrophic levels of rainfall damage to the northeastern United States, flooding New York City’s subway system and halting air travel at airports.2 Just last year, the deadly Hurricane Ian struck Florida and South Carolina, causing the second largest insured loss after 2005’s Hurricane Katrina.3
First Street Foundation asserts more than 14 million properties across the United States are susceptible to flood damage.4 Like homes, commercial structures are at great risk, and those constructed of metal are no exception. Since the hurricanes and storms that cause flooding cannot be prevented, it behooves those designing, constructing, and retrofitting commercial metal facilities to design and build for resiliency. Leveraging high-performance, weather-resistant building materials is key for preventing damage, as well as the costs associated with it, when a severe storm or hurricane occurs.
Closed-cell spray polyurethane foam (SPF) is a resilient material often used within the building envelope of metal facilities. When applied in walls, ceilings, and floors, and on the roof, closed-cell SPF protects the structure from serious, costly damage.
A Water-resistive Barrier with Flood-resistance
SPF is ideal for continuous insulation (ci) applications in metal facilities and can be used in both interior and exterior applications where it replaces commonly utilized rigid extruded polystyrene insulation (XPS) and polyisocyanurate (PIR) foam boards. As demonstrated by ASTM D 2842 and ASTM C 1338, the material offers low water absorption and resistance to mold. It excels as a water-resistive barrier (WRB) on exterior applications and has also been tested in accordance with ASTM E 2357 with a pressure of up to 6.26 psf (300 Pa) for air barrier assemblies, which included ASTM E 331 (AC71), Water Penetration Testing. The testing result for air barrier assemblies showed extremely high performance and proved no water leakage through the spray foam.
The Federal Emergency Management Agency (FEMA) has also designated it a Class 5 material when applied in walls, ceilings, and floors—the highest classification for building products, indicating strong resistance to floodwater damage. The Class 5 designation means the material requires no special waterproofing protection, can survive wetting and drying, and may be successfully cleaned after a flood to render it free of the most harmful pollutants.5 SPF provides commercial facility owners whose facilities endured a flood event with monetary and time savings. And, while it may be applied as continuous insulation and qualify as a Class 5 material, it is also notably the only cavity insulation approved by FEMA and given the highest floodwater resistance designation. When applied under slab as insulation, SPF is also flood-resistant.
Structural Strength, Improved Wind Resistance
The application of SPF in above-grade walls can also increase the structural strength of buildings and improve wind resistance. The degree of hardening depends 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 SPF than a post-frame constructed building with 29-gauge corrugated metal panels. When installed, SPF essentially glues the assembly together, reduces the potential for movement, and adds a tensile strength average ranging from 103.4 to 172.4 kPa (15 to 25 psi).6 Some SPF manufacturers offer even greater tensile or compressive strength performances.
The Spray Polyurethane Foam Alliance (SPFA) conducted racking performance tests in 1992 and 1996, and at Architectural Testing Inc. in York, Pa., in 2007, demonstrating medium density SPF installed at 32 kg/m3 (2 lb/cf) increases racking strength by 70 to 200 percent in wall assemblies sheathed with oriented strand board (OSB), plywood, gypsum wallboard, vinyl siding, and polyiso board. The research proved 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 polyisocyanurate (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 SPF in walls.7
Roofing and Wind Uplift
Not only is SPF insulation an ideal solution for metal-constructed buildings in hurricane-prone regions, but spray foam roofing is as well. The material forms a monolithic membrane over the roof and offers a compressive strength of approximately 275.8 to 379.2 kPa (40 to 55 psi).
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, a result of wind pulling flashings and copings away from a roof’s edges, which can ultimately lead to devastating structure damage. Some high-performance spray foams demonstrate wind uplift resistance by meeting the high-velocity hurricane zone (HVHZ) criteria of the Florida Building Code (FBC) (Miami Dade Notice of Acceptance [NOA]). The material’s ability to withstand leaks due to hail is also unsurpassed.
Notably, a review of roof damage following Hurricane Katrina found buildings roofed with spray foam performed well without blow-off of the SPF or damage to flashings. The report concluded that spray foam kept the roofs intact, prevented moisture from entering the buildings, and protected the structures from hail and debris.8
With the increasing number of hurricanes, the use of SPF in metal facilities is also increasing, particularly among architects, builders, remodelers, roofers, and owners outfitting their projects and properties for weather resiliency.
Maxime Duzyk is the director of building science and engineering for Huntsman Building Solutions, a global leader in spray polyurethane foam (SPF) solutions. Visit Huntsman Building Solutions at huntsmanbuildingsolutions.com and contact Duzyk at mduzyk@huntsmanbuilds.com.
Notes
1 BBC News, “Hurricane Ida: One Million People in Louisiana Without Power,” Aug. 31, 2021, bbc.com/news/world-us-canada-58378788
2 NPR, “Ida Brings Historic Flooding to Northeast, Kills at Least 18 People Across 4 States,” Sept. 2, 2021, npr.org/2021/09/02/1033513900/historic-flooding-hurricane-ida-new-york.
3 CNBC, “Hurricane Ian Caused the Second-Largest Insured Loss on Record After Hurricane Katrina,” Dec. 1, 2022, cnbc.com/2022/12/01/hurricane-ian-was-costliest-disaster-on-record-after-katrina-in-2005.html.
4 First Street Foundation, The First National Flood Risk Assessment: Defining America’s Growing Risk,
assets.firststreet.org/uploads/2020/06/first_street_foundation__first_national_flood_risk_assessment.pdf.
5 Federal Emergency Management Agency (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.
6 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.
7 Architectural Testing, Performance Test Report Rendered to Spray Polyurethane Foam Alliance, Project: Racking Load Tests, 2007.
8 National Institute of Standards and Technology, Performance of Physical Structures in Hurricane Katrina and Hurricane Rita: A Reconnaissance Report, 2006.
via www.metalconstructionnews.com
