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Advanced enclosure failure investigation · Lesson 2 of 4

Advanced enclosure failure investigation: materials, standards and design constraints

What ES-1 tests and what it does not, how to read a manufacturer rating, what field data show, and the numbers behind galvanic corrosion, zinc loss and thermal movement.

You will be able to: Read ES-1 and a published rating correctly, match each failure family to the material property and number that governs it, and say whether a number is the standard's, a manufacturer's, an AFS register value or a typical value.

18 min · 12 slides · 17 questions

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Slide 1 of 12

What ES-1 is and is not

ES-1 is a test standard for low-slope roofs, 2:12 or less. It gives the basic requirements only for resistance testing of roof edge systems under simulated wind load conditions.

A coping, or an edge system whose exposed horizontal component exceeds 4 in., is tested under RE-3.

ES-1 puts gutters beyond its scope and points to ANSI/SPRI GT-1 for gutter testing.

Sources

Videos for this lesson

What this video shows: A metal roofing supplier's short introduction to galvanic reaction: dissimilar metals touching with moisture, copper, steel, aluminum and fastener examples, and prevention at selection and installation. Checked against the video's own description only.

Video: Mixing Metals on a Metal Roof? How Galvanic Reaction Causes Roof Failure by The Metal Roofing Channel, on YouTube. Chosen from the video's published description.

Glossary

ES-1
ANSI/SPRI/FM 4435/ES-1, a test standard for resistance of roof edge systems to simulated wind load on low-slope roofs; it tests assemblies and sets no safety factor.
RE-3 test
The ES-1 test for copings and edge systems whose exposed horizontal component exceeds 4 in.; top and face loads are applied together at 1.73 to 1.
Sustained pressure
The pressure, in psf, that Drexel publishes for a tested edge assembly; Drexel says the design engineer must apply the factor of safety.
Area ratio
The size of the corroding (anode) metal compared with the protected (cathode) metal; a small anode on a large cathode corrodes faster.
ISO 9223 category
A class from C1 to CX describing how corrosive an atmosphere is; AGA publishes zinc corrosion-rate bands for each.
G90
A zinc coating designation: minimum 0.90 oz/ft2 of zinc on both sides together, about 0.0008 in. on each surface.
Point of fixity
The place where a metal piece is held so it cannot move; movement is measured from it to the floating end.