Architectural Flashing Supply
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Tier 5 · Architectural Design and Building Science

Flashing geometry and movement accommodation

How an architect or specifier gives flashing room to move: choosing the design temperature range, the fixed point and the joint family, working the movement, checking the geometry against AFS fabrication limits, and reviewing the drawings for defects.

4 lessons · about 45 min · 13 diagrams · 3 videos

Version 1.0.0

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Lessons

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  1. Lesson 1 · 12 min · 12 slides · 9 questions

    Flashing geometry and movement accommodation: principles and terminology

    What makes a flashing run move, which decisions the drawings make about it, where a run is held, what restrains it and how lengths are joined, with the roof safety rule that applies on a site visit.

    You will be able to: Define design temperature range, fixed point, sliding clip, restraint and the main ways lengths are joined, and name the decisions in the drawings that give a flashing run room to move.

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  2. Lesson 2 · 10 min · 11 slides · 7 questions

    Flashing geometry and movement accommodation: materials, standards and design constraints

    How coefficients differ by metal and by source, why zinc needs a roll direction, how published design ranges and specifications differ, and what ED-1 says about thickness and cleats.

    You will be able to: Compare published coefficients by metal, choose and record a design temperature range from published examples, and name the standards and specifications that set joint and thickness rules for roof edge metal.

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  3. Lesson 3 · 12 min · 12 slides · 8 questions

    Flashing geometry and movement accommodation: methods and worked application

    A design sequence from temperature range to fabrication check, worked on a 40 ft aluminum run and on piece joints, with the AFS limits a movement detail must fit and the notes the installer needs.

    You will be able to: Apply a documented design sequence to a run of flashing: state the range and fixed point, work the movement, share it across joints, check differing metals, and test the detail against AFS fabrication limits.

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  4. Lesson 4 · 11 min · 12 slides · 8 questions

    Flashing geometry and movement accommodation: defects, verification and case study

    Defects that come from the drawings rather than the field, what the sources say about oil canning, a drawing review checklist, and a fictional case study rewritten from range to fabrication check.

    You will be able to: Diagnose movement defects that start in the drawings, explain the corrective options, and record the calculation, the marked-up detail and the review for a run of flashing.

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Practical task

Prepare a movement review for a straight run of roof edge metal on a drawing set you choose. State a design temperature range with its source, pick the fixed point, work the movement for your metal and run length, choose the joint family, and check the profile against AFS limits. Mark anything the documents leave open as a written question to the designer.

Hand in

  • The movement calculation with every input labelled as an example or sourced, the coefficient source named and the zinc roll direction stated if zinc is used
  • A marked-up sketch of the run showing the fixed point, each joint, the joint family at each and the joint travel the detail must allow
  • The completed drawing review checklist for the run, with each item marked and any failure explained
  • A list of open questions for the designer, written as questions and not settled with an invented figure

Rubric

CriterionMeets the standard when
RangeThe design range is stated as a metal surface range and its source is named, with no air temperature used in its place.
MovementMovement is worked each side of the installation temperature with a named coefficient source, and the result is shown for the anchor chosen.
Fixed pointOne fixed point is marked for each continuous piece (the length between movement joints) and no detail holds both ends of a piece.
JointsEach joint is a lap, or a gap with a splice plate, and the travel it must take is stated from the calculation.
FitThe profile is checked against the AFS limits for piece length, flat width, end flange, segment between bends and hem return, and anything outside them is flagged for AFS.

Module quiz

10 questions drawn from a bank of 32; a new set each attempt. Pass mark 80%.

1. Which temperature goes into the movement calculation?
2. Where does NRCA say the fixed point location should be, across the panels?
3. Over 10 ft and 100 degF, how much more does aluminum move than galvanized steel, from the AFS register?
4. Which condition does the proposed 2025 revision of ED-1 name as a result of roof edge elements that cannot expand and contract freely?
5. A panel is fixed in the middle with both ends free. How does its maximum end movement compare with the same panel fixed at one end?
6. What does ED-1 say about appliances such as air terminals, signs or antennae on a roof edge system?
7. Which metal has the longest bar in the proposed ED-1 revision's chart of a 10 ft length and a 100 degF change?
8. VMZINC prints 0.022 mm/m per degC for zinc. Which direction does that value apply to?
9. At what height above lower levels does OSHA 1926.501(b)(10) apply to roofing activities at the unprotected sides and edges of a low-slope roof?
10. The 40 ft aluminum run is held at its centre and set at 70 degF. How far does each end move when expanding, for VA's range?