Wind-vented roofing systems, also known as negative pressure roof systems, have been protecting commercial buildings for over 40 years. Despite their remarkable performance, they’ve remained relatively under-the-radar in the roofing industry. Why?
The original owner of the technology held 25 separate utility patents, controlling the rights to the system. Rather than heavily investing in marketing, they focused on extensive testing and scientific validation. As a result, widespread industry awareness was limited early on.
Additionally, the system was disruptive to the status quo. It offered:
- Greater wind resistance
- Hurricane-level warranties
- Faster installation
- Lower total installed cost
Understandably, large manufacturers—who couldn’t match these features—saw it as a threat. Many responded with aggressive marketing campaigns casting doubt on the system, often based on misunderstandings of the underlying supporting science.
How Wind Damages Roofs
As wind hits a structure, it turns vertically and intersects horizontal winds passing over the building. This intersection of wind creates an uplift pressure that was scientifically tested, proven and named for the scientist that developed the core theory in 1738, Daniel Bernoulli. The Bernulli principle is now a critical design consideration of all building designs. This interaction of converging winds generates negative pressure—creating suction, increasingly at the corners and perimeters of the roof. These areas are most vulnerable to roof blow-offs and almost all low slope roof blow-offs are initiated at the corners and perimeter.
Most traditional roofing systems resist this force using heavy adhesion or additional mechanical fastening. In contrast, wind-vented systems successfully work with the wind rather than unsuccessfully against it. “Working with Mother nature has proven to generate a more positive result than trying to work against her”.
What Is a Wind-Vented (Airtight) Roof System?
Our CAT 5 Roof Design, by IRSI harnesses Bernulli created uplift wind pressures to secure the roof membrane more tightly during high wind events.
Core Components:
- Lower Pressure Boundary – Installed as the foundation of the system.
- One-Way Vortex Valves – Placed in the perimeter and corners to capture uplift and transfer it into the airtight system.
- Limited Linear Mechanical Fastening – Reduces the need for excessive screws and plates or adhesives across the field of the roof.
How It Works
When wind flows over the building, one direction vortex valves allow a controlled uplift entrance into the air- tight assembly, pulling air from beneath the roof membrane. This lowers the pressure beneath the roof, causing the top membrane to press against the insulation and deck. Rather than fighting uplift forces, our system effectively uses them to extract air from the airtight roof assembly. The result of the existing air extraction within the assembly is the roof membrane and all components within the airtight assembly is organically pulled and secured downward—effectively locking the roofing layers in place with greater force the harder the wind blows.
This concept is like fully adhered roofs. The difference between conventional fully adhered and wind vented fully adhered is the adhering component. One uses glue while the other uses a vacuum. All glues are moisture sensitive and are at the mercy of the condition of what they are adhering to.
An interesting feature worth further consideration is that the system’s attempt to extract air through a naturally created vacuum, from the airtight roof assembly increases proportionately to the increasing wind speed. “Greater wind speeds create greater blow off protection.”
Result: Superior “wind blow off” resistance without unsuccessful over-reliance on glues or additional fasteners.
Advantages of the CAT 5 Wind-Vented Roofing System
- Fewer Fasteners & Faster Installation
Reduces labor time, materials, and installation cost. - Maximum Wind Uplift Resistance
Perfect for hurricane-prone and high-wind regions.
Backed by our 150 mph Hurricane Wind Warranty (with no exclusions for hurricane events). - Minimal Disruption & Tear-Off
Often installed over the existing roof—no need for costly and disruptive removal. - Moisture Control & Removal
Actively removes existing trapped moisture without tear-off.
We guarantee the removal of the moisture without the removal of roofing materials. - Double Waterproof Protection
Primary membrane + secondary perimeter seals using airtight, watertight materials and term bars.
Backed by a 30-Year No Dollar Limit Warranty (Materials & Labor).
The Moisture Misconception
Moisture surveys are often used before re-roofing, but they’re far from exact. Results vary depending on:
- Sensor settings
- Interpretation
- Outdoor conditions
- Internal temperature/slope/insulation makeup
And yet, roof manufacturers often allow overlays over known wet roofs. Why? Because their warranties exclude coverage for pre-existing moisture, ponding water, and future leaks related to those conditions.
CAT 5 Roof Design offers a better solution:
Our system technology has 40 years proving that it removes roof assembly moisture, prevents condensation by creating a low-pressure assembly environment which mitigates future moisture damage— and we guarantee the results.
Rising Costs, Smarter Choices
Full tear-offs may feel safer—but in today’s market, they can be prohibitively expensive, take too long, cause unnecessary disruption, and is not environmentally friendly. Insulation installation costs alone have tripled in recent years. CAT 5’s ability to recover roofs without tear-off offers a cost-effective, high-performance solution.
The Safe Choice for Your Next Project
CAT 5 Roof Design is the most wind-resistant roofing technology on the market today. We’re proud to offer:
- 150 mph Hurricane Wind Warranties
- 30-Year NDL Waterproof Warranties
- Proven 40-year track record
- Moisture mitigation guarantees
- Fast, cost-effective installation
Ralph Jewell
Managing Partner, Integrated Roofing Systems, Inc.
877-767-0030
introofsys.com
