Demystifying the World of Roof Flashing

Demystifying the World of Roof Flashing

Understanding the Complexities of Fly-By Curtain Wall Parapets

As a roofing enthusiast, I’ve always been fascinated by the intricate world of roof flashing. It’s a crucial component of any building’s envelope, yet it’s often overlooked and misunderstood. Today, I want to take you on a deep dive into the realm of fly-by curtain wall parapets – a design feature that adds both visual appeal and technical complexity to roofing systems.

Let’s start by exploring the concept of a fly-by curtain wall parapet. Imagine a building with a sleek, all-glass facade that seems to seamlessly transition into the roofline. This effect is achieved by integrating the roofing membrane with the curtain wall near the roof surface, while the vision glass and curtain wall frame continue above. The result is a “glass box” effect where the roof line disappears into the facade, maximizing views and creating a visually stunning aesthetic.

However, this design approach is not without its challenges. Designers must navigate the technical complexities of ensuring air and water barrier continuity between the roof and the curtain wall system. Unlike traditional opaque parapet structures, the fly-by parapet with transparent glazing presents unique obstacles in concealing roofing materials and maintaining the integrity of the building envelope.

Curtain Wall Basics: Stick-Built vs. Unitized Systems

To fully understand the design considerations for fly-by curtain wall parapets, we need to first explore the two main types of curtain wall systems: stick-built and unitized.

In a stick-built curtain wall system, the frame mullions and glass or opaque panels are installed and connected together piece by piece on-site. This approach typically relies on rectangular aluminum extrusions for the framing elements.

On the other hand, a unitized curtain wall system is composed of large, pre-assembled units that are factory-glazed, shipped to the site, and then erected on the building. These units feature a split horizontal mullion design, with interlocking components like the “stack head” and “stack sill.”

Regardless of the system, curtain walls must be designed and anchored to the building to accommodate various in-service movements, such as vertical floor slab deflections, horizontal inter-story drift, and thermal movements. The specific anchor configurations can vary, with options like F and T clips, J hooks, or angles.

Designing Fly-By Curtain Wall Parapets

Now, let’s dive into the design considerations for integrating a fly-by curtain wall parapet with a protected membrane roof assembly.

Concept 1: Unitized Curtain Wall with Independent Outrigger Support
This approach utilizes an independent outrigger support system to provide the necessary structural support for the fly-by parapet. The outrigger may either resist both gravity and lateral loads (top-hung) or just lateral loads (dead-loaded on the unit below). The key features of this concept include:

  • Integrating the roofing membrane into the split horizontal mullions of the unitized curtain wall system
  • Securing the outrigger system to the building’s structure to support the fly-by parapet

Concept 2: Stick-Built Curtain Wall with Independent Outrigger Support
The stick-built curtain wall system lacks the split horizontal mullions of the unitized system, so the design must be adapted accordingly. In this case, the outrigger support system is used to independently support the parapet, creating a separation between the fly-by parapet and the lower curtain wall. This allows the roofing membrane to extend between two parallel horizontal mullions adjacent to the roof curb, mimicking the functionality of the split mullion in the unitized system.

Concept 3: Stick-Built Curtain Wall with Internal Reinforcing Posts
When independent outrigger support systems are not feasible, an alternative approach using steel reinforcing posts embedded in the vertical mullions can be employed to resist lateral loads. This option avoids the visual impact of exposed framing, but it requires careful detailing to maintain the continuity of the air and water barrier around the steel posts.

Concept 4: Integrated Membrane and Metal Flashing
For situations where neither the split horizontal mullions nor the outrigger support systems are available, a combination of membrane and metal flashing can be used to create a reliable seal. This approach involves turning the roofing membrane up the interior side of the glass and mullions, while also incorporating metal flashing that turns into the glazing pocket.

Regardless of the specific concept, the key to successful fly-by curtain wall parapet design is early coordination and communication among all stakeholders, including the design and construction teams. By addressing the unique challenges and leveraging the right systems and techniques, you can achieve a visually stunning and functionally robust roofing solution.

The Importance of Customization and Best Practices

While the concepts discussed provide a general framework for integrating fly-by curtain wall parapets, it’s important to note that each project presents its own unique set of design constraints and challenges. Curtain wall manufacturers often have proprietary approaches for constructing these features, and designers must evaluate whether their standard details and kit-of-parts can fulfill the project’s design intent and long-term performance expectations.

In some cases, a custom solution may be necessary to overcome the limitations of commodity products, which can be inherently less customizable and more prone to air and water leakage issues. By keeping the following best practices in mind, you can navigate the complexities of fly-by curtain wall parapets and deliver a roofing solution that exceeds your clients’ expectations:

  1. Early Collaboration: Engage all parties involved in the design and construction process as early as possible to ensure a seamless integration of the curtain wall and roofing systems.
  2. Manufacturer Expertise: Consult with the selected curtain wall manufacturer to understand their standard details and capabilities, as well as the feasibility of custom solutions if required.
  3. Comprehensive Detailing: Carefully consider the overall system integration, including the interface between the roofing membrane, flashing, and the curtain wall components, to maintain the integrity of the building envelope.
  4. Workmanship Considerations: Recognize the importance of precise installation and detailing, especially for complex solutions like the stick-built curtain wall with internal reinforcing posts.
  5. Ongoing Research and Evolution: Stay informed about the latest industry advancements and best practices, as the field of fly-by curtain wall parapet design is continuously evolving.

By embracing these principles and leveraging the right expertise, you can help your clients unlock the full potential of fly-by curtain wall parapets, delivering not only a visually stunning roofing solution but also a highly functional and durable building envelope.

Exploring the Benefits of Southern Roofing Co.

As you navigate the complexities of roof flashing and fly-by curtain wall parapets, you’ll want to partner with a roofing contractor that has the expertise and resources to ensure a successful project. That’s where Southern Roofing Co. comes in.

Our team of seasoned professionals has a deep understanding of the latest roofing technologies and construction techniques, including the intricacies of fly-by curtain wall parapets. We work closely with architects, designers, and building owners to develop customized solutions that meet their unique requirements, all while maintaining the highest standards of quality and safety.

Whether you’re tackling a new construction project or need to address complex roofing challenges in an existing building, Southern Roofing Co. is here to guide you every step of the way. Our commitment to excellence and attention to detail ensures that your roofing project not only looks great but also performs flawlessly for years to come.

So, if you’re ready to demystify the world of roof flashing and unlock the full potential of your building’s envelope, reach out to the experts at Southern Roofing Co. today. We’ll be more than happy to discuss your project and explore how we can help you achieve your vision.

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