Most building owners spend more time thinking about the roofing membrane than the metal around the perimeter. We understand why. The membrane covers nearly the entire roof, while the edge represents only a small portion of the visible system. From a commercial roofing project perspective, that small area deserves careful attention.

Roof edge securement is the combination of membrane termination, edge metal, cleats, fasteners, and supporting construction used to secure a roofing system at the perimeter of a building. It is not simply decorative trim. The International Building Code specifically addresses metal edge systems on applicable low slope roofs because these components must resist calculated wind forces.

For applicable built up, modified bitumen, and single ply roof systems with slopes below 2 units vertical in 12 units horizontal, Section 1504.6 of the 2021 International Building Code requires metal edge systems, except gutters and counterflashing, to be designed and installed for the wind loads specified in Chapter 16 and tested using the RE 1, RE 2, and RE 3 methods of ANSI/SPRI ES 1. 

For building owners, that requirement establishes an important principle. The roof perimeter should be selected as an engineered part of the roofing assembly, not simply chosen according to appearance or metal thickness.

Why Roof Edge Securement Deserves Attention

Duro-Last® educational material identifies improper fastening and perimeter edge installation among common roofing installation errors. The publication states that statistics cited at the time estimated that more than half of roof warranty claims were attributed to metal edge failures. It also explains that improperly installed fasteners can cause individual fasteners to fail, increasing pressure on the remaining fasteners and potentially contributing to failure of the roof.

That is significant because the edge connects several important parts of the roofing assembly.

The membrane has to terminate correctly. The metal has to remain attached. Fasteners have to engage appropriate supporting material. Cleats and other components have to correspond with the tested configuration. The completed assembly then has to satisfy the wind resistance required for that particular building.

This is why we do not evaluate commercial roof edge securement by asking only whether the metal looks substantial. The better question is whether the installed system corresponds with a tested assembly and the design requirements for the property.

Wind Resistance Is Not Uniform Across a Commercial Roof

One of the most important concepts for a building owner to understand is that wind forces are not treated as identical across the entire roof. Roof design distinguishes between different roof areas because the pressures that affect the perimeter and corners are not necessarily the same as those affecting the field of the roof.

Duro-Last industry documentation explains that mechanically attached systems can use a higher density of fasteners and plates in perimeter and corner zones, according to design criteria, to accommodate increased wind uplift forces. The specific attachment requirements therefore depend on the wind design criteria established for the project.

We cannot responsibly give every owner one universal fastener spacing, one perimeter width, or one wind rating that applies to every property. Building geometry, height, location, exposure, roof construction, applicable code, and the selected roofing system can affect the design.

A roofing proposal should therefore identify the system appropriate for the actual project rather than relying on a perimeter detail simply because it has been used successfully somewhere else.

What ANSI/SPRI ES 1 Actually Tests

ANSI/SPRI/FM 4435/ES 1 2022 establishes standardized test methods for edge systems used with low slope roofing systems. The standard includes three test procedures, RE 1, RE 2, and RE 3, which address different roof edge conditions.

RE 1 applies to roof edge termination in certain dependently terminated roofing systems.

RE 2 evaluates edge flashing systems where the exposed horizontal component is 4 inches or less.

RE 3 applies to copings and other roof edge systems where the exposed horizontal component exceeds 4 inches.

That distinction matters because different perimeter configurations respond differently to applied loads.

Just as important, the standard requires manufacturers to provide documentation identifying components that have been tested. That documentation is to be made available to the building owner or the owner’s representative. Installation instructions for compliant edge systems must also include fastener and cleat requirements.

This gives owners a practical way to evaluate roof edge securement. Rather than asking whether an edge system is strong, ask what testing supports it.

A Tested Component Is Not Automatically a Tested Assembly

This is one of the more important details that can be missed during specification review. SPRI explains that an individual tested component cannot simply be combined with unrelated untested components to create an ES 1 compliant system. Fascia and coping assemblies must be tested as complete assemblies because the load is applied to the metal surface exposed to the wind.

That means a contractor cannot necessarily take a tested cleat, add a different cover, and assume that the resulting configuration provides the same tested performance. SPRI also explains that even copying the dimensions of an ES 1 tested product does not automatically create an ES 1 tested product. Differences in material, fabrication methods, equipment, and quality control can affect performance.

For a building owner, this provides an important decision rule: Evaluate the complete tested edge assembly, not just individual pieces of it. That is the type of distinction that can separate a documented perimeter design from an assumption.

Metal Thickness Alone Does Not Determine Performance

Another common misunderstanding is that thicker edge metal automatically means better wind resistance. Metal thickness can matter, but it is not the only design factor.

SPRI’s edge design guidance states that minimum metal thickness requirements do not account for other important design factors, including fastening pattern and frequency, continuous cleats or intermittent clips, stiffening ribs, and breaks in the edges. SPRI also notes that RE 2 and RE 3 testing may determine that increased metal thickness is necessary for higher wind loads.

That gives owners another useful rule, do not compare commercial roof perimeter systems by gauge alone. Fastener type, spacing, cleat configuration, geometry, substrate, and tested assembly performance can all affect the system. This becomes especially important when two proposals appear similar at first glance, because a line item that simply lists edge metal may not provide enough information to determine whether the proposals actually specify equivalent perimeter assemblies.

What Can Fail During Edge Testing

Understanding how edge systems are tested helps make the importance of attachment clearer.

The ANSI/SPRI/FM 4435/ES 1 2022 commentary identifies several examples of component failure that can prevent a roof edge system from performing as designed. These include full fastener pullout, fastener pull through, collapse of a cleat, fascia, or cover, and disengagement of the cover from a cleat or clip.

Those failure modes illustrate why the visible metal is only one part of the system. A properly shaped cover cannot perform as designed if the attachment underneath it fails.

Likewise, a strong cleat cannot compensate for an unsuitable substrate or installation that differs from the tested arrangement. This is why commercial roof edge securement should be reviewed from the visible metal all the way into the supporting construction.

What We Verify Before Roof Installation

A useful perimeter review should happen before the new roofing membrane reaches the building edge.

For commercial projects, we want the following questions resolved before installation progresses:

• What building code applies to the project?
• What wind design criteria apply to the building?
• What roof edge system is specified?
• What ES 1 testing applies to that system?
• Does the proposed installation match the tested configuration?
• What fasteners and cleats does the manufacturer require?
• What material will receive those fasteners?
• Is the existing perimeter construction suitable for the proposed attachment?
• Are damaged or deteriorated perimeter materials being removed or retained?
• Do wall conditions, coping conditions, or other building components affect the proposed termination?

This type of review helps owners compare proposals based on complete assemblies rather than membrane brand and project price alone. It also identifies perimeter conditions before they become field decisions during installation.

Why Duro-Last Roofing Systems Still Require Complete Perimeter Planning

We install Duro-Last roofing systems on commercial roofing projects. Duro-Last states that its commercial roofing systems are available in widths up to 10 feet to help reduce rooftop seaming. Its roofing systems portfolio includes PVC, PVC plus KEE, fleece backed PVC, and TPO options.

For our applications using Duro-Last roofing systems, the membrane remains only one component of the roof assembly. The perimeter still requires appropriate termination, attachment, edge metal, and supporting construction. The benefit of a quality membrane does not eliminate the need to design and install the perimeter correctly.

Duro-Last designs and manufactures perimeter edge metal products including perimeter and drip edge metal flashing, reglet, and coping. The manufacturer states that many of its edge metal products are rated according to ANSI/SPRI ES 1 or GT 1 standards. When properly installed, Duro-Last® states that these edge details provide a watertight seal and protection from water and wind damage between the roof and the rest of the building.

For owners considering a Duro-Last roofing system, this makes it possible to discuss the membrane and perimeter as connected parts of the complete roof system.

What Building Owners Should Request in a Roofing Proposal

Before approving a commercial roof replacement, we recommend that owners request enough information to understand the perimeter system being proposed. At minimum, the proposal discussion should identify the edge product or system, relevant testing, attachment requirements, and any assumptions concerning existing perimeter construction.

The owner should also know who is responsible if unsuitable supporting material is discovered after the existing edge is removed. This is a practical issue because an edge attachment ultimately depends on the construction receiving the fasteners.

A clear proposal should reduce the number of critical decisions that have to be made unexpectedly after installation begins. When evaluating roof perimeter wind resistance, documentation is more useful than adjectives. Terms such as heavy duty, premium, or strong do not establish tested performance.

A test report, manufacturer requirement, or approved system configuration provides information that can actually be evaluated.

Inspecting the Roof Edge After Installation

The roof edge should continue to receive attention after installation is complete.

Duro-Last recommends routine roof inspections at least twice per year, during spring and fall, and also recommends inspecting the roof after severe weather.

Its owner checklist specifically directs building owners to examine metal flashings for rust, detachment, damage, and deteriorated sealant. The same maintenance material advises checking roof edging, edge metal, and perimeter edging for signs of problems or strain.

That makes the perimeter an appropriate part of every routine inspection.

Owners should look for visible movement, loose metal, separated components, damaged sealant where applicable, corrosion, or changes from the condition documented after installation.

Following high wind or other severe weather, the perimeter also deserves attention even when there is no obvious interior problem. Duro-Last specifically notes that the absence of water entering the building does not mean a roof has avoided storm damage.

For additional maintenance guidance, we provide information about Duro-Last inspection and maintenance requirements in our commercial roofing FAQs.

 

A Practical Decision Framework for Building Owners

We recommend evaluating roof perimeter wind resistance through four questions.

First, what does the building require?

Determine the applicable code and project wind design requirements.

Second, what system has been proposed?

Identify the actual edge assembly rather than accepting a general description such as metal fascia or coping.

Third, what documentation supports it?

Confirm the appropriate ES 1 testing and manufacturer installation requirements.

Fourth, can the existing building support the specified attachment?

Verify that the perimeter construction receiving the system is appropriate for the specified fasteners and configuration.

If one of those questions cannot be answered, the perimeter design deserves additional review before installation.

Your Roof Is Only as Secure as Its Perimeter

Roof edge securement represents a relatively small portion of the roofing system by area, but it should receive the same level of design attention as the membrane itself. The International Building Code requires applicable low slope metal edge systems to satisfy specific wind design and testing requirements. SPRI requires edge assemblies to be tested in configurations that represent the system being installed, while Duro-Last provides documented edge metal products, many of which are rated according to ANSI/SPRI ES 1 or GT 1.

For owners, the most useful question is not whether the edge metal looks substantial. Ask whether the complete perimeter assembly has been selected, tested, attached, and installed for the requirements of your building. That question provides much more useful information about commercial roof edge securement than appearance alone.

If you are planning a roof replacement or evaluating the condition of an existing commercial roof, the perimeter should be part of that conversation from the beginning. Our team can evaluate the roof, review existing edge conditions, and help determine the appropriate next steps for your building.

Planning a commercial roofing project? Contact us to schedule a commercial roof evaluation and discuss your building’s roofing needs.

SCHEDULE MY COMMERCIAL ROOF EVALUATION

 

Frequently Asked Questions About Roof Edge Securement

What is roof edge securement?

Roof edge securement is the combination of membrane termination, edge metal, cleats, fasteners, and supporting construction used to secure the roofing system at the perimeter of a building. Applicable low slope roof edge systems are subject to wind design and testing requirements under the International Building Code.

What is ANSI/SPRI ES 1?

ANSI/SPRI/FM 4435/ES 1 is a test standard for edge systems used with low slope roofing systems. It contains RE 1, RE 2, and RE 3 test procedures for different edge conditions and requires installation information that includes fastener and cleat requirements.

Can a contractor combine different tested edge components?

Not automatically. SPRI states that fascia and coping systems need to be tested as complete assemblies. Combining a tested component with an unrelated untested component does not by itself create an ES 1 compliant assembly.

Does thicker edge metal mean better wind resistance?

Not by itself. SPRI guidance notes that metal thickness does not account for fastening pattern, fastening frequency, cleats, clips, stiffening features, and other design factors. Tested assembly performance provides a more complete basis for evaluation.

Why do roof corners and perimeters receive different attention?

Wind design recognizes different roof areas because design pressures vary with roof location and building conditions. Duro-Last industry documentation notes that perimeter and corner areas can require greater fastener and plate density according to design criteria.

Does Duro-Last manufacture perimeter edge metal?

Yes. Duro-Last offers perimeter flashing, drip edge flashing, reglet, coping, and related products. The manufacturer states that many products are rated according to ANSI/SPRI ES 1 or GT 1.

How often should building owners inspect roof edge metal?

Duro-Last recommends roof inspections at least twice each year, during spring and fall, as well as after severe weather. Its maintenance checklist includes checking metal flashings and perimeter edging for damage, detachment, rust, deteriorated sealant, and signs of strain.

What should an owner ask before approving a roof perimeter system?

Ask which code applies, what wind design requirements apply, what complete edge assembly is specified, what testing supports it, what fasteners and cleats are required, and whether the existing supporting construction is suitable for the proposed attachment.