When building owners think of roof replacements, they often focus on the roof surface itself. However, parapet walls on institutional buildings can sometimes present the biggest challenge. In short, a parapet wall is an extension of an exterior wall that projects above the roofline, helping protect the roof assembly, manage wind uplift, provide fall protection and sometimes conceal rooftop equipment.
Because roofing membranes must be able to seamlessly transition across parapet walls, these areas are among the most critical details in a roofing system.
Today we present a micro case study highlighting how the Elite Roofing team adapted to unexpected parapet conditions on an occupied school building in Vaughan, ON, and came up with a solution that protected the membrane while maintaining a safe learning environment for students and staff.
The Project Challenge: An Occupied School With Limited Access
We were asked to complete a roof tear-off of an existing roof over a metal deck substrate. The first challenge was that the client opted to get the project done during the school year rather than over the summer break. This meant that school was in session during all phases of construction.
We did our best to communicate with school staff in relocating students from rooms directly below the areas being worked on each day. Still, the noise of construction, as well as the smell of the asphalt, required us to take additional precautions. In addition to those factors, we had to contend with site restrictions (including a newly-constructed playground) that limited our access to no more than 10 to 15 feet from the building itself.
Site conditions made an asphalt-based roofing system difficult due to the following challenges:
- Limited staging space
- No convenient location for disposal containers
- Restricted material access
- Need to minimize odors and disruptions around students and staff
As a result, the project team shifted to a self-adhered roofing system, with special attention paid to the parapet wall conditions.
Why Existing Parapet Conditions Created a Risk
Unlike traditional asphalt-based applications, self-adhered membranes require proper surface preparation, and that includes being able to directly adhere to clean, compatible substrates.
The existing parapet walls of the school’s roof contained old asphalt materials and residual contamination accumulated over years of exposure. When new self-adhered membranes are applied directly over a contaminated surface, it can lead to:
- Adhesion failure
- Delamination
- Reduced long-term performance
- Premature system deterioration
Self-adhered roofing membranes depend on clean, stable surfaces. The presence of contaminants such as greases, oils, bacteria, chemicals, organic growth, and dirt can adversely affect the integrity of the roof membrane, according to the Asphalt Roofing Manufacturers Association.
Contaminated Parapets: The Hidden Threat to Long-Term Performance
Like the entire roofing system itself, parapet walls are constantly being exposed to:
- UV radiation
- Weather conditions (snow, ice, rain, heat, etc.)
- Aging asphalt materials
- Residual oils and surface contaminants
- Previous roofing repairs
These conditions make direct membrane adhesion extremely difficult if not impossible, especially over the long term. Even when contamination can’t be seen by the naked eye, it’s there and can disrupt the bond between the new roofing membrane and the existing substrate.
For self-adhered systems, the risk is higher because adhesion is what holds the membrane in place at vertical transitions and upturns.
The Solution: Creating a Clean Separation Layer
Rebuilding the entire parapet isn’t cost-effective or necessary for that matter, provided that the proper accommodations are made. That’s where the ingenuity of our team came into play. We knew we couldn’t adhere directly to the existing parapet surfaces, so we came up with a plan to create a clean, uncontaminated surface between the existing parapet materials and the new roofing membrane.
Here’s what we did for the commercial parapet wall roofing portion:
Laminated Plywood Across the Top of the Parapet
- Installed over the existing parapet cap area
- Created a new attachment surface
- Eliminated concerns about contamination affecting adhesion
Cement Board Along the Interior Vertical Surface
- Installed on the inside face of the parapet
- Provided a clean substrate for membrane installation
- Improved long-term adhesion performance
Together, these materials created a separation layer between the old roofing components and the new self-adhered system.
Why This Extra Step Was Worth It
While our solution to commercial parapet wall roofing added another layer of complexity to the project, this extra step was necessary not only to create proper adhesion but to greatly reduce long-term risk.
Benefits of our approach included:
- More effective membrane adhesion
- Reduced delamination risk
- Greater system reliability
- Stronger performance at critical parapet transitions
- Enhanced long-term waterproofing protection
Most importantly, the approach addressed the root cause of the problem rather than attempting a short-term fix that would have created more problems for the client later.
How We Created a Reliable Membrane Bond Over Existing Parapet Conditions
Elite Roofing recently completed a successful project at an occupied school in Vaughan, Ontario. Highlights include:
- Existing parapet contamination successfully addressed
- Clean substrate created for membrane adhesion
- Delamination concerns eliminated
- School operations maintained throughout construction
- Safe environment preserved for students and staff
- Long-term roofing performance protected
The Elite Advantage
Commercial roofing projects don’t always unfold the way we think they will. Last-minute challenges often come up that we have to solve on the fly. Our ability to identify potential problems and adapt before those issues become failures is what separates us from the rest. In this case, we took a fresh approach to a unique situation, coordinating our work process around an active school environment to minimize disruption and maintain safe conditions. The result was a roofing detail designed for long-term performance, while taking the safety and comfort of students and staff into account every step of the way.
Contact Elite Roofing
If you’re planning a roof replacement and want expert guidance on complex roofing details such as parapet walls, contact us to request a quote and let us know about your upcoming project.
