Wind loads and roof edge resistance · Lesson 4 of 4

Wind loads and roof edge resistance: defects, verification and case study

How edges fail in storms and tests, why an edge must be installed as tested, the order and values in one manufacturer coping guide, appliances and gutters that disturb an edge, how to verify a tested system, and a case study of an RE-2 gravel stop specified where RE-3 applies.

You will be able to: Recognise how roof edges fail and which installation changes void a test, follow the installation order of one tested coping, verify a tested edge from its documents, and correct a specification that names the wrong test.

10 min · 12 slides · 6 questions

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Slide 1 of 12

How edges fail

FEMA's handbook says public buildings with low-slope membrane roofs often fail at the edges in high winds, from lifting and peeling of metal edge flashings, copings and fascia covers.

It recommends designing these elements to resist wind uplift as per ANSI/SPRI ES-1, which the IBC references.

Sources

Hurricane and Flood Mitigation Handbook for Public Facilities, Fact Sheet 3.3.2: Roof Systems, Low-Slope Roofs (FEMA P-2181, March 2022) - FEMA

Glossary

Kickout: The part of a cleat that the drip, or hemmed lower edge, of a coping or fascia cover hooks over, as in Drexel's Econo Coping guide: the coping is hooked over the kickout and rotated over the parapet.
Fabricated miter: A corner piece made from lengths of the edge system; ES-1 requires no special test of it, but the system it comes from must have been tested to the design loads of the corner region.
FM Approval: Approval by FM Global of edge metal tested at FM per ANSI/SPRI/FM 4435/ES-1 and listed in RoofNav; SPRI's seminar says it is often specified but should only be required on FM insured buildings.
Sub-listed fabricator: In SPRI's description of NRCA sub-listing, a fabricator that pays a fee, receives fabrication details for edge products NRCA has tested and has its facility audited; it applies only to select details fabricated and installed as tested.