Architectural Flashing Supply
Start a Quote
Failure analysis and forensic diagnosis · Lesson 1 of 4

Failure analysis and forensic diagnosis: principles and terminology

The words of failure analysis; the three conditions water entry needs; why a guide written for walls still teaches good habits; oil canning as a defect that is not always a failure; and the limits of what AFS can state.

You will be able to: Tell a symptom, a failure, a defect and a cause apart, name the three conditions and the forces of water entry, explain why a leak shows up away from its entry, and state what AFS can and cannot say about a returned part.

9 min · 8 slides · 7 questions

All lessons in this module
Slide 1 of 8

The call-back: symptom, failure, cause

A symptom is what someone sees: a stain, a lifted edge, a wave.

A failure is an outcome, such as water getting in; it is not yet a cause.

A cause is the condition that, if corrected, stops the failure happening again.

These are this course's working words, not a standard's wording.

Sources

Glossary

Symptom
What an occupant or inspector sees, such as a stain, a lifted edge or a wave. Where a symptom appears is not necessarily where its cause is.
Failure
An outcome: the element did not do its job, for example it let water in or released from the building. It is not yet a cause.
Cause
The condition that, if corrected, stops the failure happening again. This is the course's working definition, not a standard's.
Contributing factor
A condition that made a failure possible or worse, but whose correction alone would not stop it recurring.
Three conditions of water entry
Water present, an opening, and a force to move the water. All three are needed together; this course draws them as a triangle for memory, from Beall's list.
Hypothesis
A stated explanation of a failure that a test could show to be wrong.