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Failure analysis and forensic diagnosis · Lesson 3 of 4

Failure analysis and forensic diagnosis: methods and worked application

A six-step documented method; what to record; tests in order of least damage and why one test does not settle it; a movement calculation; demand against tested capacity; confidence words; and the job packet.

You will be able to: Run the six-step method, document a part so another person can use the record, choose the least destructive test that could prove a hypothesis wrong, calculate expected movement, and compare an edge demand with a tested capacity or say none exists.

10 min · 10 slides · 8 questions

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Slide 1 of 10

The method in six steps

This course's method has six steps: observe, document, hypothesise, test, conclude, verify.

Observe and record before touching anything.

If a test result does not fit the hypothesis, revise the hypothesis and test again.

It is a teaching method, not ASTM or IIBEC terminology.

A documented method for failure analysisFlow of six lettered steps: A observe and record, B document, C state a hypothesis a test could disprove, D test with least damage first, then a decision, does the result fit, with a no arrow looping back to C to revise, and yes continuing to E conclude with a confidence word and F verify after repair. An amber note says to get the roof manufacturer written position before flooding a roof.A documented methodAObserve and recordTouch nothing yetBDocumentPhotos, measurements,drawings, recordsCState a hypothesisOne a test could disproveDTestLeast damage firstDoes the resultfit?no: reviseyesEConcludeWith a confidence wordFVerify after repairThe test that reproduced itnow does notGet the roof manufacturer's writtenposition before flooding a roof: a floodtest can void a warranty (IIBEC, 2025).

Six lettered steps: observe and record, document, state a hypothesis, test, then a check that the result fits, with a no arrow back to the hypothesis, then conclude with a confidence word and verify after repair. An amber note says to get the roof manufacturer written position before flooding a roof.

A
Observe and record before touching anything
B
Document with photographs, measurements, drawings and records
C
State a hypothesis that a test could disprove
D
Test, least damage first
E
Conclude with a confidence word
F
Verify after the repair
This course's own method, drawn from the habits in the IIBEC leak case and the E2128 preliminary assessment; it is a teaching method, not a published standard.

Sources

Videos for this lesson

What this video shows: A manufacturer's explanation of what electronic leak detection finds in a membrane with an active leak, and how it differs from infrared and capacitance surveys. A vendor video, checked against its description.

Video: Forensic Electronic Leak Detection (ELD) Testing for Existing Roofs with Active Leaks by Detec Systems, on YouTube. Chosen from the video's published description.

Glossary

Replicate a leak
To make a leak happen again on purpose with a controlled test, so a hypothesis about where water enters can be checked.
Infrared thermography
A survey that shows temperature differences, used to find moisture in a roof assembly; it locates wet areas but not always the point of entry.
Metal surface temperature
The temperature of the metal itself, which MCA says may be more than 100 degrees above the air temperature; movement depends on it, not on the air.
Demand
The pressure an edge part must resist at a place on the roof, worked out from wind speed, exposure, height and enclosure.
Confidence word
One of this course's four words for how sure a finding is: fact, consistent with, most likely, or cannot be determined.