Expansion joints and thermal movement
Why flashing metal changes length with temperature, how coefficients and published specifications set joint spacing, and how to lay out, install, inspect and document expansion joints on a run.
4 lessons · about 40 min · 8 diagrams · 0 videos
Version 1.0.0
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Lesson 1 · 9 min · 11 slides · 7 questions
Expansion joints and thermal movement: principles and terminology
Why sheet metal changes length with temperature, which temperature to use, where a run is fixed and where it floats, what stops it moving, and the roof safety rules that apply while you work on joints.
You will be able to: Define thermal movement, fixed point, floating end, restraint and the two kinds of expansion joint, and name the fall protection and protective equipment rules that apply on the roof.
Not startedStart →Lesson 2 · 10 min · 11 slides · 7 questions
Expansion joints and thermal movement: materials, standards and design constraints
Coefficients by metal, who decides joint type and spacing, the ED-1 rules, two federal specifications that give different spacings, and why sealant fills a joint but is not the joint.
You will be able to: Identify the expansion coefficients of the common flashing metals, who sets joint spacing and detail, and why published spacing rules disagree.
Not startedStart →Lesson 3 · 11 min · 12 slides · 7 questions
Expansion joints and thermal movement: methods and worked application
The documents to read first, a field sequence, three worked examples with their inputs shown, the gaps the install guides print, and the installation sequence for a gap-and-splice-plate run and a gutter expansion joint.
You will be able to: Apply a documented field method to set out and install expansion joints, work the movement of a run with stated assumptions, and install a gap-and-splice-plate run and a gutter expansion joint.
Not startedStart →Lesson 4 · 10 min · 12 slides · 7 questions
Expansion joints and thermal movement: defects, verification and case study
What restrained and cracked runs look like, the joint checks for gravel stops, copings and gutters, a field checklist, a joint-count example and a case study to document.
You will be able to: Recognise the defects that movement causes, check a finished run against a field checklist, work a joint count with stated inputs, and document a defect and a corrective request.
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Practical task
Prepare a joint packet for a straight run of edge metal. Choose a metal and a run length, work the movement with your stated temperatures and the AFS register coefficient, and mark up a sketch showing the fixed point, each joint and its type. Compare your joint spacing with the specification you are using and note any conflict you would send to the designer.
Hand in
- The movement calculation with every input labelled as an example or sourced, and the coefficient source named
- A marked-up sketch of the run showing the fixed point, joint locations, joint type and gap or splice plate at each
- A joint spacing comparison against the specification you chose, with any conflict written as a question for the designer
- The field checklist completed for one joint, with the metal temperature and gap you would record
Rubric
| Criterion | Meets the standard when |
|---|---|
| Movement | The movement is worked from the installation temperature in both directions using metal temperatures, with the coefficient source named. |
| Fixed point | The fixed point is marked and the movement at each free end is stated for that anchor. |
| Joints | Each joint has a type, a location tied to the specification, and a gap or plate as the maker or specification prints it. |
| Conflicts | Any disagreement between documents is written as a question to the designer and no figure is invented to settle it. |
| Checklist | The checklist is completed against the sketch and records the metal temperature and measured gap. |