Spray Foam and Hurricanes: Roof Decks and the Superdome

Short answer

Sprayed under a roof deck, closed-cell foam glues the sheathing to the rafters and to itself. In University of Florida tests, OSB roof panels held only by closed-cell foam resisted 2.6 times the wind uplift of comparable nailed-only panels, averaging 196 pounds per square foot. After Hurricane Katrina peeled 80% of the Louisiana Superdome's roof membrane, the 422,000-square-foot roof was rebuilt with 3 inches of sprayed polyurethane foam. FEMA lists closed-cell foam as acceptable flood-resistant insulation.

Key points

In 2007 University of Florida tests (sponsored by a foam maker), OSB roof panels held only by closed-cell foam sprayed from below resisted 2.6 times the uplift of nailed-only control panels, averaging 196 psf.
A peer-reviewed 2014 follow-up wetted foam-retrofitted roofs with simulated leaks: the panels kept high uplift capacity, but the wood took on significant moisture, and small bond samples lost up to 54% of their tensile strength over 16 weeks while staying "above design wind pressures by a minimum factor of 3.75."
Katrina tore two holes about 4 by 100 feet in the Superdome roof and peeled about 80% of its EPDM membrane; the replacement was a 3-inch spray polyurethane foam roof with a urethane coating, finished 32 days early in July 2006.
FEMA's 2025 flood-materials bulletin rates sprayed polyurethane foam and closed-cell foams "Acceptable" for floors, walls and ceilings below flood level, and open-cell foams "Unacceptable."

Why roofs fail in high wind

In a hurricane, wind flowing over a roof pulls up on it, and wind pushing in through a broken window or door pushes up from inside. The roof sheathing is usually the first thing to go: if panels lift off, water pours in and the walls lose their bracing at the top.

Most roof decks are held down only by nails into the rafters or trusses. Building codes in hurricane regions have pushed for closer nail spacing and ring-shank nails. Researchers also looked at something already being sprayed into attics: closed-cell foam.

What the University of Florida tests found

A team led by David Prevatt at the University of Florida ran static wind-uplift tests on 30 wood roof panels in 2007, in a study sponsored by foam maker NCFI. Panels retrofitted from below with closed-cell spray foam were compared with panels fastened only with nails.

University of Florida uplift tests (2007): roof sheathing retrofitted with closed-cell spray foam resisted 2.6 times the uplift of nailed-only panels, an average of 196 psf. Sprayed from below, the foam bonds the sheathing to the framing.

The report's summary: "roof panel wind uplift capacity can be increased by 2.6 times the uplift capacity of control roof panels fastened with nails only," with the foam-retrofitted panels averaging 196 psf. Nails grip at points; the foam bonds along the whole joint between the sheathing and the framing.

The honest follow-up: what a roof leak does

The same research group then asked what happens when a foamed roof leaks for months. In a peer-reviewed 2014 paper in the Journal of Architectural Engineering, they wetted foam-retrofitted roof panels with simulated rainwater intrusion over 16 weeks.

The results cut both ways. The panels "maintained high wind uplift failure capacities," and the bond after 16 weeks "remained above design wind pressures by a minimum factor of 3.75." But the roofs "experienced significant moisture buildup in the wood substrates," and the wood-to-foam bond lost as much as 54% of its tensile strength with time. A companion study found the uplift capacity itself was not affected by the high moisture content.

The practical reading: closed-cell foam under a deck adds real wind resistance, and a roof leak above foam has to be found and fixed, because the foam slows the wood's drying. Our article on whether spray foam traps moisture covers how to check.

The Superdome

When Hurricane Katrina hit New Orleans in 2005, the Louisiana Superdome lost large parts of its roof: the storm "ripped two holes in the Superdome's roof—each about 4 feet wide and 100 feet long—and peeled about 80 percent of the EPDM membrane off the roof," according to Professional Roofing, the National Roofing Contractors Association's magazine.

The original 422,000-square-foot roof was a steel deck, 2-inch polyisocyanurate board and a 60-mil EPDM rubber membrane. The rebuild was "a 3-inch-thick spray polyurethane foam- (SPF-) based roof system with a urethane coating system," with the deck flutes filled with foam. Work ran from March 13 to July 18, 2006, and finished 32 days early. FEMA put $176 million toward emergency measures, debris removal, mitigation and repairs to the building.

The Superdome after Hurricane Katrina, its dome roof stripped in large patches down to the bare deck — The Louisiana Superdome on September 5, 2005, after Hurricane Katrina stripped much of its roof membrane, and on August 14, 2006, with the new spray polyurethane foam roof system in place.Photos: Win Henderson/FEMA and Ed Edahl/FEMA, public domain

The Superdome from above in 2006 with a clean, uniformly white new roof — The Louisiana Superdome on September 5, 2005, after Hurricane Katrina stripped much of its roof membrane, and on August 14, 2006, with the new spray polyurethane foam roof system in place.Photos: Win Henderson/FEMA and Ed Edahl/FEMA, public domain

What failed in 2005 was the membrane and board system, not foam, and no one can say how a foam roof would have done in that storm. What the rebuild shows is the choice made for a landmark roof in a hurricane zone: a continuous, fully adhered sprayed roof with no fastened seams to peel. The same contractor later sprayed the 1.9-million-square-foot roof of New Orleans' Ernest N. Morial Convention Center, citing wind-uplift resistance.

Flood: what FEMA says

FEMA's Technical Bulletin 2 sets which materials can be used below the flood elevation in flood zones. Its January 2025 edition rates "sprayed polyurethane foam (SPUF) or closed-cell plastic foams" as acceptable insulation for floors, walls and ceilings, and "open-cell plastic foams," cellulose and cotton as unacceptable. Closed-cell foam doesn't soak up floodwater the way open-cell and fibrous insulation do. See is spray foam waterproof?

What it means in Western PA

Western PA doesn't get hurricanes, but it gets straight-line windstorms, the remnants of tropical storms and lake-effect wind off Erie, and plenty of flood-prone basements. Closed-cell foam on a roof deck, in a sealed attic or on basement and crawl space walls brings the same three properties: a bonded layer, an air barrier, and insulation that tolerates water. In climate zone 5, foam under a roof deck must also meet the condensation rules in IRC R806.5; see sealed attics.

Thinking about a sealed attic or a roof deck? Price My Project or call (814) 208-3478.

FAQ

Does spray foam make a roof stronger in wind?

Closed-cell foam sprayed under the deck does. In University of Florida tests it raised the uplift capacity of roof sheathing to 2.6 times that of nailed-only panels. The tests used closed-cell foam.

What kind of roof does the Superdome have?

After Hurricane Katrina, its 422,000-square-foot roof was rebuilt in 2006 as a 3-inch spray polyurethane foam roof with a urethane coating, replacing the original EPDM membrane over polyiso board.

Is closed-cell spray foam allowed in flood zones?

Yes. FEMA's Technical Bulletin 2 (2025) lists sprayed polyurethane foam and closed-cell foams as acceptable flood-damage-resistant insulation; open-cell foam is not.