During any violent storm, including hurricanes, tornadoes and wind shear, the constant battering of wind forces against a home or building over the course of the storm can cause serious damage to the structure. Roofs can ultimately fail opening up the indoors to all kinds of damage and flooding as well. This is especially true of standard stick-built or wood frame construction. Typical construction methods are no match for hurricane force winds from 100 to 150 miles per hour.
Another problem with severe wind storms and traditional frame roofs is wind uplift. You have probably seen video footage of roof structures lifting off a building’s frame in storms. This phenomenon is caused by rapid air pressure drops and shifts that accompany these types of severe weather. The physics of this is similar to a vacuum where rapidly moving wind moves quickly by a home or building causing the dramatic air pressure drop and creates a giant vacuum effect. The intense amount of pressure on the outside of the home causes the roof to lift off of the wall framing.
Spray foam is recognized by the Federal Emergency Management Agency as a way to protect and strengthen a building’s structure against such severe wind forces. The bonding power of foam helps it hold fast during periods of intense stress on a structure. In addition, closed cell foam’s water resistant qualities help protect building materials during storm surges which can accompany hurricanes.
Foam increases the structural strength of roof members and materials so much so that it can significantly reduce the chance that water will invade the roof structure and cause damage. This fact was proven in a 2007 study undertaken by the University of Florida as it tested the effectiveness of spray foam insulation during severe storm conditions. Their study concluded that foam provided 2 to 3 times the normal protection from wind uplift and roof sections reinforced with closed cell spray foam were able to withstand hurricane force winds up to a category 4.