An Educational Guide for Commercial Property Owners in the Piedmont Triad
Across the Piedmont Triad, many warehouses, manufacturing facilities, and other commercial and industrial buildings have metal roofing systems.
As those roofs age, property owners may begin dealing with warning signs that a commercial roof needs repair, including recurring problems around fasteners, seams, penetrations, and other vulnerable areas. At that point, it may seem that the only long-term solution is to remove the existing metal roof and replace it.
That isn't always the case.
Depending on the condition and construction of the existing roof, a single-ply metal roof retrofit may allow a new TPO roofing system to be installed over the existing metal roof without completely tearing it off.
But this isn't simply a matter of installing TPO over old metal panels. The existing roof must first be evaluated and properly prepared, and the new roofing assembly must be designed around the building that's already there.
What Is a Single-Ply Metal Roof Retrofit?
A metal roof retrofit uses the existing metal roof as part of the foundation for a new single-ply roofing assembly.
Rather than removing the entire existing roof, necessary repairs are made and the metal panel profile is addressed with the appropriate insulation and substrate components before the new membrane is installed.
B&D Roofing Solutions installs Carlisle SynTec roofing systems, including Sure-Weld® TPO. TPO is a reinforced thermoplastic roofing membrane whose seams are joined using hot-air welding.
Once completed, the building has a new membrane roofing system installed over the existing metal roof rather than another round of repairs to individual fasteners, seams, and problem areas.
The Existing Metal Roof Still Has to Be Prepared
Keeping the existing metal roof doesn't mean ignoring its condition.
Before a retrofit begins, the roof must be evaluated for deterioration and other conditions that could affect the new roofing system.
Loose or damaged components may need to be repaired. Deteriorated metal panels may need to be replaced. Corrosion, penetrations, perimeter conditions, drainage problems, and other deficiencies must be evaluated and addressed as appropriate for the project.
The goal isn't to hide an aging roof beneath a new membrane.
It's to create a sound foundation for the new roofing assembly.
If the existing roof or structure isn't suitable for a retrofit, another roofing solution may be necessary.
Not All Metal Roofs Are Built the Same
Commercial metal roofs come in different panel configurations, and those differences matter when designing a retrofit.
B&D encounters different profiles on commercial and industrial buildings throughout the Piedmont Triad, including corrugated and trapezoidal metal panels.
The shape and depth of those panels affect what is required above the existing metal roof. The building's structural framing beneath the panels can affect how the new roofing system is attached.
That's why a metal roof retrofit should be treated as a roofing system designed around the existing building, not simply as a membrane placed over an old roof.
The Existing Metal Profile Determines the Insulation System
Before the TPO membrane can be installed, the irregular surface of the existing metal roof must be properly addressed to create a stable, supported substrate.
How that's accomplished depends on the existing metal panel profile and the roofing assembly being installed.
For example, on a trapezoidal metal roof, profile-shaped flute filler can be installed between the raised portions of the existing panels. Additional insulation or cover board is then installed above the flute filler as specified for the roofing system, creating the substrate for the new TPO membrane.
On other metal roof profiles, a different recovery or insulation assembly may be appropriate.
The attachment method matters, too. On mechanically fastened retrofit systems, specialized fasteners may extend through the new roofing assembly and secure into the building's structural purlins beneath the existing metal panels.
For a property owner, the important point is simple:
The insulation and attachment system must be designed around the roof that's already on the building.
Once the substrate is properly prepared, the new TPO membrane can be installed and its seams heat-welded to create the new weathering surface.
Why Consider a Retrofit Instead of Tearing Off the Metal Roof?
For a qualifying building, one of the biggest advantages is straightforward:
Much of the existing roof can remain in place.
A complete tear-off requires removal and disposal of the existing roofing material and can temporarily expose portions of the building as work progresses.
A retrofit can reduce the amount of demolition and disposal required and may limit some of the disruption associated with complete roof removal.
The new roofing assembly may also provide an opportunity to add insulation above the existing metal roof. The amount and type of insulation depend on the specified system and existing building conditions.
And because TPO is available in highly reflective finishes, the completed system can provide a reflective roof surface. Actual energy performance depends on the complete roof assembly, insulation, building construction, and operating conditions.
Does Every Metal Roof Qualify?
No.
That's one of the most important things for a property owner to understand.
Before recommending a retrofit, B&D evaluates the existing roof and building conditions.
That may include:
- Condition of the existing metal panels
- Corrosion or deterioration
- Existing leaks or evidence of moisture
- Roof slope and drainage
- Fasteners, seams, penetrations, and perimeter conditions
- Panel profile
- Structural conditions and supporting purlins
- Requirements of the proposed roofing system
The fact that TPO can be installed over certain metal roofs doesn't mean it should be installed over every metal roof.
The existing building has to be suitable for the proposed system.
What Happens After the Roof Is Prepared?
Once necessary repairs are completed and the appropriate insulation and substrate components are installed, the new TPO roofing system can be installed over the prepared assembly.
Sheets of reinforced TPO membrane are positioned across the roof and secured according to the specified roofing system. Adjacent membrane sheets are joined with hot-air welded seams.
Curbs, penetrations, drains, perimeter conditions, transitions, and other rooftop details are incorporated into the new roofing system.
This is an important difference between a retrofit and continuing to chase individual leaks on an aging metal roof.
Instead of repeatedly addressing individual fasteners, panel laps, and isolated trouble spots, the retrofit creates a new weathering surface over the existing metal roofing system.
What About Warranties?
Warranty options depend on the selected roofing assembly, membrane, attachment method, existing building conditions, project specifications, and current manufacturer requirements.
As a Carlisle Authorized Applicator, B&D Roofing Solutions evaluates the appropriate Carlisle system and available warranty options for each qualifying project rather than assuming one assembly or warranty applies to every metal roof.
A Metal Roof Doesn't Necessarily Have to Become Another Metal Roof
This may be the most important takeaway.
When an older commercial metal roof reaches the point where recurring repairs are no longer providing good long-term value, the choices aren't necessarily limited to:
keep patching it
or
tear everything off and install another metal roof.
For the right building, a properly designed single-ply retrofit can provide another path.
The existing metal roof becomes part of the foundation for a new roofing assembly designed around the building's actual conditions.
The B&D Promise
We believe commercial property owners deserve honest recommendations—not sales pressure.
A metal roof retrofit is an excellent solution for some buildings. For others, repair, restoration, or complete replacement may make more sense.
Our job is to evaluate the existing roof, understand how the building is constructed, explain the available options, and recommend the solution that provides the best long-term value.
Whether that means a Carlisle single-ply retrofit or another roofing solution, we'll explain the reasons behind our recommendation and tell you what we would recommend if it were our own building.
