Performance versus prescriptive specifications · Lesson 4 of 4

Performance versus prescriptive specifications: defects, verification and case study

Four recurring failure patterns, why a field change breaks an assembly that was tested, what a federal quality control plan inspects, and a hypothetical case taken from a vague clause to a fix.

You will be able to: Recognise the four ways a specification fails, say what a federal quality control plan checks, and work a hypothetical case from a vague clause to a fix with evidence.

9 min · 10 slides · 7 questions

All lessons in this module

Slide 1 of 10

Four ways a specification fails

Four failure patterns recur: a performance clause with no test method; a prescriptive detail that cannot meet the stated performance; a field change from the tested installation; and two methods that conflict.

This list is the course's own synthesis, and each pattern is tied to a source on the slides that follow.

Sources

ANSI/SPRI/FM 4435/ES-1 Test Standard for Edge Systems Used with Low Slope Roofing Systems (approved November 21, 2022; free read-only copy) - SPRI (Single Ply Roofing Industry)
ANSI/SPRI ED-1 Design Standard for Edge Systems Used with Low Slope Roofing Systems, proposed revision of October 2025 (not an approved edition) - SPRI (Single Ply Roofing Industry)
UFGS 07 60 00 Flashing and Sheet Metal (08/23, change 1: 05/25) - USACE, NAVFAC and AFCEC, via the Whole Building Design Guide

Glossary

Quality control plan: A plan, submitted before work starts, with a checklist of points to be observed and documented observations; the federal guide lists size and thickness, fastening and joining, and installation.
Tested assembly: The exact combination of cover, cleat, fasteners and spacing that was put through the test; ES-1 says to install it in the same manner as tested.
Engineer of record: The designer who carries design responsibility; ED-1 says it rests with the designer of record, and wind design pressures are theirs to set.