Roof Edge Securement

Perspectives
A Quarterly Information Source from Benchmark, Inc.
Volume 54 April 2006

Roof Edge Securement

by Kevin Ernster, RRC

There is no debate as to the importance of proper roof edge securement. The following quotations from a number of roofing professionals address the importance of the roof edge.

“The majority of roof covering failures resulting from windstorms involve improperly designed or

constructed perimeter flashings.” (1)

“Wind’s effect on metal components is not new information. It has long been widely recognized that the edge condition is vitally important.” (2)

“The most common initiating conditions for wind damage is lifting of edge metal.” (3)

“As with past windstorm events, many roofing failures are directly related to inadequate attachment of metal edge flashings. . .” (4)

Text Box: Section of coping displaced by wind. Note the bent attachment clips. A continuous attachment clip would have prevented this condition. The securement of the roof at the perimeter, whether it be by gravel stop, nosing or coping, has long been recognized as one of the most important elements in maintaining the integrity of a roof system during high wind conditions. Yet, despite this recognized fact, it has only been recently that standards for edge securement have been established. Prior to this standard, the design and fabrication of this most important element was usually left up to the roofing contractor, or in reality, his sheet metal foreman.

As with the other elements of the roof, proper roof edge design takes into account the building location and specific building attributes such as wind speed, height, size and roof edge configuration. The components of the edge design must be of sufficient strength and configuration to withstand the wind forces for a specific building and location. Even with this level of detail, how do we know a design will withstand the wind loads placed upon it

The 2003 International Building Code addresses this issue. Under Section 1504 “Edge securement for low-sloped roofs,” paragraph 1504.5 states: “Low-slope membrane roof systems metal edge securement, except gutters, . . . .shall be designed in accordance with ANSI/SPRI ES-1.”

The ANSI/SPRI ES-1* standard establishes criteria for determining local basic wind speeds, uplift pressures and the criteria for static testing of fabricated roof edge assemblies.

The International Building Code has been adopted in 27 states, and is expected to be adopted by more states in the future. In these 27 states, if the roofing contractor designs, fabricates and installs a metal edge, coping or fascia that has not been tested to the ES-1 criteria, the detail is in violation of the building code.

It is also true for an architect or consultant who designs an edge component that has not been tested and the contractor installs the untested design, that the edge securement is in violation of the code. Several companies do manufacture pre-fabricated metal edge components that are tested and meet the ES-1 standard. In some cases, they are tested to wind speeds greater than 170 mph. However, these components tend to be substantially more expensive than shop fabricated components.

As a specifier and designer of roof systems, this code requirement placed a burden on us. It limited our choice of edge Text Box:
The failure of the roof edge condition resulted in this roof blow off. designs to ES-1 tested pre-manufactured copings and gravel stops, and placed a financial burden on our clients due to these systems’ higher costs.

In the winter of 2005, Benchmark elected to test standard roof edge designs to the ES-1 standard. Utilizing our designs, a fabricator was contracted to build the edge details, which we then had tested at an accredited lab. The test results documented that the Benchmark coping and gravel stop designs are capable of withstanding winds in excess of 120 mph, depending on building location, height and ground roughness.

With this approval, Benchmark roof edge designs, when constructed and installed as detailed, will meet the criteria of Section 1504.5 of the International Building Code.

We know of no other roof consultant in the country to take on this challenge and expense. We feel our roof edge testing program will reduce project costs to our clients while ensuring code compliance.

To view our roof edge details, go to our website at www.benchmark-inc.com and click on the “Search Articles” link at the bottom of the home page.

1. FM Global Data Sheet 1-49

2. Thomas Smith, AIA: “Hurricane Hugo’s Effect on Metal Edge Flashings”

3. RCI Interface, February 2005, “Lessons learned from Florida hurricanes.”

4. “Wind Loads on Metal Edge Flashings”, by James McDonald, Proposal Paper, October 1992

*ANSI - American National Standards Institute

SPRI - Single-ply Roofing Institute

ES-1 - Edge Securement 1 test