VRS ... Harness the Wind.

The Stevens Vented Roof System (VRS) combines a reliable, time proven Stevens EP™, Stevens EV® (Elvaloy HP) or Stevens CSPE (made with Hypalon® from DuPont) roofing membrane with an air-sealed assembly and release vent technology.  This creates a system that neutralized the power of the wind and keeps the membrane tightly secured to a monolithic deck or air barrier over steel or wood. All without the need for added cost of fasteners, stone ballast, pavers or adhesives in the field of the roof.

Wind Uplift is The Common Roof Enemy

Wind uplift occurs when the air pressure below the roof system is greater than the air pressure above the system.  As wind flows over the building, the pressure directly above the roof surface decreases.  Simultaneously, atmospheric pressure from below attempts to equalize this pressure differential, resulting in an upward push of air from below the roofing system, referred to as wind uplift.

Additional uplift forces are generated on roof membranes whenever air can readily move from the building's interior to the underside of the roofing assembly, commonly through air-permeable decking without an air barrier, such as steel or wood, or through cracks, penetrations or perimeters in monolithic decks.  In these situations, the membrane itself acts as an effective air barrier, receiving the full impact of the uplift load.

The height of the building, surrounding ground terrain, and position relevant to the wind direction can further effect wind uplift forces.  Turbulent vortices at the building's perimeter and corners are produced when updrafts, created as wind is deflected up the side of the building, meets the horizontally moving air stream at rooftop level.  The resulting vortices not only cause violent turbulence, but can further magnify the differential between external and internal air pressures, resulting in even greater uplift forces.

Stevens VRS Cheats the Wind

The Stevens VRS is installed over a monolithic deck or an air permeable deck in conjunction with an air barrier.  The membrane is air-sealed at all through-deck penetrations and at the roof perimeter, effectively eliminating air movement from the building's interior to the underside of the roofing system.  Any existing air between the membrane and deck is vented to the exterior through a series of strategically placed one-way air-release vents.  Thus, VRS technology transfers the uplift load from the roofing system to the deck, creating a vacuum within the system, which results in a roof that lays flat and stays in place during wind storms.

 

 

 

 

 

 

 

 

	Negative external and positive internal pressure differential creates an uplift force that tries to push conventional, nonvented, non-sealed roof systems off the building.
	Stevens VRS specifications require a sealed roof deck to prevent wind uplift forces from reaching underside of the roof system. One-way VRS valves harmlessly release any expanding air between the membrane and deck to the exterior.