SELECTING AND TESTING EDGE METAL
BY MIKE RYAN, CHIEF TECHNICAL OFFICER AND STAFF ARCHITECT
NM ARCHITECT 4037, MEMBER OF NRCA AND ICC
This newsletter will dive into different metal terminations at low slope roof systems and the testing requirements for them. I know this sounds rather dull and that no amount of prose or roofing poetry is going to make it any more exciting, but it is a rather important component of the roof assembly and deserves at least a few paragraphs! I had a modest understanding of the code requirements for roof edge securement when I was responsible for preparing contract documents while at architectural firms: I knew that the exposed roof edges and parapets can experience some of the highest forces on the building and if the edge metal released, it could pull away the roof membrane with it, leaving the building and contents exposed to the elements. Similarly, if metal coping fails and becomes a projectile, it could pose a danger to people or property. I also knew that Chapter 15 of the International Building Code (IBC) stated that copings and edge metal at low-slope roofs needed to be designed and installed to resist wind loads, and that somehow ANSI/SPRI ES-1 was to be involved in the testing. I would include these code requirements on the documents and hope for the best!
If you want to stop reading here, the short of it is that Chapter 16 of the IBC defines the parameters upon which to determine the wind forces at the roof edge, and ANSI/SPRI ES-1 provides the testing methods for assemblies to quantify how much force each is able to resist in a given direction. When the design team includes the design pressures for the edge metal in the plans or specs, the contractors can select pre-tested assemblies from multiple sources that meet or exceed the upward and/or outward force expected. Know that these pre-tested assemblies are limited in the horizontal and vertical dimension: If
the designer wants a custom profile or larger horizontal or vertical faces, special testing of that system may be required to meet the code requirements. For those of you still reading, the next iteration of the IBC will reference ASCE 7-16 instead of 7-10 (as mentioned in the last newsletter); this will result in increased design pressures for most types of buildings in most of the risk categories. These increased forces make the code requirement for designing and installing roof edge metal to resist those forces all the more important, especially in high wind zones and for taller buildings. Remember that this testing and installation requirement only applies to edge securement for low slope (2:12 or less) built-up, modified bitumen and single-ply membrane roofing systems.
Now for the deep dive! ES-1 testing is separated into three test methods: RE-1, RE-2 and
- RE-1 applies to the edge metal of mechanically fastened or ballasted membrane roofs
systems without additional fasteners within 12” of the edge. This is the least common of
the three tests, and the units are in pounds per linear foot.
- RE-2 primarily tests outward pressure on the vertical face of edge metal and the
measurement units are in pounds per square foot.
- RE-3 is the test primarily used for metal coping that terminates the roof membrane. It
tests both upward and outward pressure resistance in pounds per square foot.
It is the responsibility of the roofing contractor to make sure that the selected metal
profiles are tested and installed to meet the given design pressures, and to ensure the
correct test is used for the specific application.
Recommendation of steps to take in the documentation process:
- Include wording from Section 1504.5 of the IBC in the drawings and specifications; “the
requirements for metal edge securement for low slope roofs are to be designed and
installed for wind loads per Chapter 16 of the IBC, and tested for resistance in accordance
with ANSI/SPRI ES-1 test methods”, or similar.
- Include the design pressures for the edge metal so all subcontractors can select and
price the assemblies accordingly. This is very important to ensure ‘apples-to-apples’ at bid
- During the submittal process, make sure submitted edge metal and coping profiles from
the subcontractors include the tested resistance pressures for outward and/or upward
forces, and those listed pressures exceed the given design pressures by a factor of 1.67,
- Although not currently a code requirement, insisting that fabricators are certified to
make ES-1 compliant metal termination would help provide an independent means of
ensuring compliance with ANSI/SPRI ES-1. Testing agencies such as Intertek Testing
Services N.A. (ITS) and Underwriters Laboratories Inc. (UL) provide stickers to be placed
on individual components (chairs, cleats and flat metal) to indicate they were made by an
- That’s all there is to it!
Additional information you may find useful:
- FM Global requirements do not apply to the current building code for edge metal securement. If the project is insured directly by FM Global and FM 4435 is referenced, then separate guidelines for quantifying and reporting test results will apply. However, if FM 4435 is referenced and the project is NOT FM Global insured, it creates confusion on the requirements for compliance and may increase cost to the project.
- Programs like Wind Calculator from METAL-ERA and roofwinddesigner.com from the NRCA can be helpful in determining anticipated pressures on a roof edge. These programs analyze simplified configurations but can be useful for the designer to determine preliminary sizing or for the General Contractor to evaluate forces on projects that do not have a design team.
- Provide wood blocking below edge metal; a 2×6 is usually best since it extends beyond the typical 4” horizontal leg of the metal. Of course any wood blocking or nailer used to attach roof edge system components needsto be designed and installed to resist the same forces as the roof edge metal.
- The roofing warranty ends where roof membrane ends; if you want the edge metal or coping to be included in that warranty, specify that the metal be made by the same manufacturer as the roof membrane. Note that this will have a cost impact on the project since it limits competition for that portion of the work.
- Maximum standard width for premanufactured copings is 32” wide (minimum is 3.5”). Note that not all fabricators are able to make copings this wide; the more common maximum width for metal coping is 16”-24”.
- When the metal coping gets wider or the edge metal face gets taller, cost is increased due to additional wood blocking requirements, thicker metal and enhanced fastening patterns. When the parapet width exceeds 18”, consider bringing the wall membrane up and over the parapet and terminating the edge with a metal fascia system (TerminEdge by Olympic Metals Group, AnchorGard SP Fascia by METAL-ERA or equal). This option is usually less expensive and provides a similar look and equal or greater wind resistance as a coping. It also resolves some of the issues from foot traffic and thermal expansion
experienced by wider copings.
- The most common vertical face maximum dimension for edge metal is 8” and the common vertical face dimensions for tested coping assemblies are between 4” and 6”.
- Once the vertical face exceeds 6”, oil canning can become an issue. Note the following ANSI recommendations for gauge of unreinforced galvanized steel based on exposed face: Up to 4” = 24 ga; > 8” to 10” = 22 ga; > 10” to 16” = 20 ga.
Finally, the NRCA keeps a current list of authorized metal fabricators in New Mexico that have ITS or UL certification for ES-1 compliant metal edge fabrication. As of this publication, they are: Allen Roofing Co. Inc. in Roswell; DKG & Associates Inc., Midtown Metals LLC and Progressive Services Inc. in Albuquerque; Smith Roofing Inc. in Las Cruces; and WWRC Inc. in Clovis, NM.