On a low-slope roof, the fascia, coping and gutter are the first things the wind grabs, so the code treats them as a tested assembly rather than trim. Order edge metal by shape alone and you can end up with a part that looks right and still fails inspection.
Why the edge gets its own code section
Most blow-offs on membrane roofs start at the perimeter. If the fascia or coping lifts, it peels the membrane off behind it and the rest of the roof follows.
IBC Section 1504.5, Edge securement for low-slope roofs, requires the metal edge on built-up, modified bitumen and single-ply roofs to be designed for the wind loads in Chapter 16 and tested to Test Methods RE-1, RE-2 and RE-3 of ANSI/SPRI/FM 4435/ES-1. Gutters are carved out of that section. That is the number in the 2015 and 2018 editions; confirm it in your adopted edition.
ES-1 covers membrane roofs. Eave and rake trim on a standing seam roof is outside 1504.5 and is handled by the panel manufacturer's engineered details, not ES-1.
What the three ES-1 tests check
ES-1 is a test standard, not a prescriptive trim spec; it does not tell you which gauge will pass. It describes physical tests on a full-size mockup of the edge: metal, cleat, fasteners, nailer and, for the membrane test, the termination, installed per the manufacturer's instructions.
| Test | What it loads | What it proves |
|---|---|---|
| RE-1 | Pulls on the roof membrane at the edge | The edge termination holds the membrane |
| RE-2 | Pulls outward on the fascia face | Fascia and cleat stay engaged under horizontal load |
| RE-3 | Pulls outward on both faces of a coping and upward on its top | The coping resists suction from the sides and from above |
RE-1 is a pass/fail pull at a fixed load; RE-2 and RE-3 are loaded against the design pressure and produce the psf rating. The whole mockup is tested because the edge fails as a system; a good fascia on a light cleat lets go well below what the metal alone suggests.
Design wind pressure: the number the listing has to beat
A tested edge carries a rating in pounds per square foot. The job carries a design pressure, worked out from wind speed, building height, exposure and roof zone; perimeter and corner zones see far higher suction than the field, and the edge sits in them.
The rating has to meet or exceed the design pressure. That number comes from the engineer of record or the manufacturer's published tables, run against ASCE 7 as IBC Chapter 16 directs. North Texas ultimate design wind speed is about 115 mph for Risk Category II under ASCE 7-16, higher for Category III and IV, but the pressure on a specific edge depends on the building, so get the number before you pick the system.
Tested assembly vs. shop-made metal
A shop can bend a fascia that matches a tested profile to the sixteenth, and it is still not a tested assembly. The rating belongs to the exact combination that went through the lab:
- Metal type and thickness: 24 or 22 gauge steel, .040 or .050 aluminum
- Profile dimensions, especially face height
- Cleat material and thickness, often heavier than the fascia
- Fastener type, length and spacing
- Nailer and substrate the assembly was anchored to
- Membrane type at the termination
Change one item and the listing no longer describes the roof. The usual ways a job voids its listing:
- Dropping gauge. The listing calls for a 22 gauge cleat; the order goes out at 24 because that is on the rack.
- Swapping fasteners. A different or shorter screw, or a nail where the listing shows a screw.
- Stretching spacing. 12 inches on center in the listing becomes 16 or 24 on the roof.
- Changing the face height. A taller fascia sees more load on the same cleat and fasteners.
- A weak nailer. ES-1 assumes an anchored nailer. A loose one is not the metal's fault, but the edge leaves with it.
A generic SMACNA detail is a sound shape, not a listing; the 7th edition Architectural Sheet Metal Manual includes a few ES-1 tested edge details, but those are rated only when built exactly as tested. Shop-made edge metal is fine where no tested assembly is required, but once the spec or code official calls for ES-1, the shape alone does not get you there.
Gutters: ANSI/SPRI GT-1
Gutters get their own standard, ANSI/SPRI GT-1: a gutter is a long sail hanging off the edge, and it loads whatever it hangs from. GT-1 tests the gutter as an installed assembly, with its brackets or straps, fasteners and the edge metal behind them, under outward and vertical loads.
IBC 1504.5 does not point to GT-1, so the requirement comes from the spec, the owner's insurer or the code official. Ask early; a tested gutter usually means a manufacturer's hanger and spacing, not a field-bent strap.
What the inspector will ask for
Have this in the file before the perimeter is covered:
- The listing or test report for the edge system, naming profile, metal, thickness, cleat and fasteners
- The rating from that listing and the job's design pressure, with the calculation or table it came from
- The manufacturer's installation instructions, since the test was run to them
- Shop drawings with face height, cleat and fastener spacing matching the listing
- For FM-insured buildings, the FM Approvals listing and the FM Data Sheet 1-49 details
Frequently asked
What does ANSI/SPRI/FM 4435/ES-1 actually test?
ES-1 runs physical load tests on a full-size mockup of the roof edge: RE-1 is a pass/fail pull on the membrane termination, RE-2 pulls outward on the fascia face, and RE-3 loads a coping on both faces and its top. RE-2 and RE-3 are loaded against the design pressure and produce the psf rating, which belongs to that exact combination of metal, cleat, fasteners and nailer.
If my shop bends the same profile as a tested edge, is it a tested assembly?
No. The listing belongs to the specific metal, gauge, face height, cleat, fastener type and spacing that went through the lab, so a matching shape without the rest of that combination is not a tested assembly. Changing any one of those items voids the listing.
Do gutters on a low-slope roof fall under ES-1?
No. IBC 1504.5 excludes gutters from its ES-1 requirement. Gutters have a separate standard, ANSI/SPRI GT-1, which tests the gutter with its hangers and fasteners as an installed assembly. IBC 1504.5 does not reference GT-1, so whether a tested gutter is required comes from the project spec, the owner's insurer or the code official.