Architectural Flashing Supply
Start a Quote
ANSI/SPRI/FM 4435/ES-1 edge systems · Lesson 2 of 4

ANSI/SPRI/FM 4435/ES-1 edge systems: materials, standards and design constraints

Demand versus tested resistance, where demand comes from, how to read Drexel published sustained pressures, what moves a rating, what a record covers, the safety-factor disagreement, and gauges, gaps and isolation in Drexel's guides.

You will be able to: Read a published edge-system rating, say what limits it and what a test record covers, and say whose number each figure is.

10 min · 11 slides · 6 questions

All lessons in this module
Slide 1 of 11

Two numbers: demand and tested resistance

Demand is the pressure the wind asks of the edge; tested resistance is what a test record says an assembly held.

IIBEC describes two steps: determine the design wind loads for each edge condition, then select flashings whose tested resistance equals or exceeds them.

A trade article names four drivers of design pressure: wind speed, building height, location and building use.

Sources

Glossary

Demand
The pressure the wind asks of an edge at a given place on a roof, found from the project's wind data by the engineer of record; not the same as what an assembly tested to.
Tested resistance
The pressure a test record says one exact assembly held; it covers that assembly only, in the size window and build that were tested.
Wall width
In Drexel's size limits for a coping, the width of the parapet wall the coping covers; a published rating is given for walls up to a stated width.
Factor of safety
A multiplier the engineer of record applies between a calculated wind pressure and the pressure an assembly must be shown to hold; published values include 1.67 (AISI S100 and ADM1) and 2.0 (ES-1, per IIBEC).