Sealants, compatibility and joint design
What a sealant is for, how to read a C920 label, which sealants suit metal and which do not, how to work out a joint width and depth, the sealing sequence, and how to test, log and diagnose a sealed joint.
4 lessons · about 41 min · 9 diagrams · 3 videos
Version 1.0.0
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Lessons
0 of 4 complete
Lesson 1 · 11 min · 9 slides · 9 questions
Sealants, compatibility and joint design: principles and terminology
What a sealant is for, where it belongs on flashing work, how to read an ASTM C920 label, the parts of a sealant joint, and the safety data sheet rule.
You will be able to: Define the terms on a sealant label and in a joint detail, say where sealant belongs on flashing work and where it does not, and state the chemical-safety rule that applies at the joint.
Not startedStart →Lesson 2 · 11 min · 10 slides · 9 questions
Sealants, compatibility and joint design: materials, standards and design constraints
The three common sealant families for metal, the silicone rule for bare metal, the order of compatibility checks, the standards map, movement class and temperature limits.
You will be able to: Compare butyl, polyurethane and silicone sealants for metal work, run the compatibility checks in order, and name the standards and specification constraints that govern a joint.
Not startedStart →Lesson 3 · 10 min · 11 slides · 6 questions
Sealants, compatibility and joint design: methods and worked application
The sealing sequence from cleaning to tooling, worked examples for joint width, depth and rod size and for a hot-day seal, and how butyl tape behaves at a lap.
You will be able to: Apply a documented sealing sequence to a coping-to-wall joint, work out a screening joint width and depth from movement, and record the assumptions and inspection points.
Not startedStart →Lesson 4 · 9 min · 11 slides · 6 questions
Sealants, compatibility and joint design: defects, verification and case study
Inspection points, the field adhesion test and its log, the common defects and their corrections, old-sealant handling, and a fictional callback to diagnose.
You will be able to: Inspect a sealed joint against the specification, run and read a field adhesion test, diagnose common sealant defects, and write a corrective action for a failed joint.
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Practical task
Produce a sealant job packet for one joint where a metal edge piece ends against a masonry wall, using an example detail you choose or one from a project drawing. Record every input and say whose value each number is.
Hand in
- A compatibility record: the metal and its finish, the neighboring materials, the sealant family you would use, and the data-sheet line that shows its ASTM C920 type, grade, class and use and the substrates its maker documents.
- A marked-up section sketch showing joint width, sealant depth, backer rod or bond-breaker tape, primer, masking and the two bonded faces.
- A screening width check: free length, temperatures, expansion coefficient and its source, movement each way, the width each class would need and the width you would propose, with units and assumptions.
- A quality checklist covering label, shelf life, width against the maker’s minimum, cleaning, temperature of the metal and the air, backing, fill, tooling, masking removal and the pull test with its log entries.
- A defect analysis of the January callback case, with causes, the corrective action and the questions you would send to the specifier.
Rubric
| Criterion | Meets the standard when |
|---|---|
| Compatibility | Names the sealant family and shows from a data sheet or the maker that it is documented for the metal, finish and neighboring materials; rules out acid-cure silicone on bare metal. |
| Joint geometry | Shows width, depth and backing consistent with the specification or data sheet, with two bonded faces and no bond at the back. |
| Movement check | Calculates movement each way from stated inputs, applies the class definition correctly, checks the maker’s minimum width, and states the check is a screening step. |
| Method and checklist | Lists the sealing sequence in order and the inspection points, including temperature of the metal, primer before the rod, and masking removal on time. |
| Defect analysis | Identifies the acid-cure silicone, the missing rod and the missing records in the case, and writes a corrective action that includes removal, retest and testing the adjacent sealant. |
| Sources and honesty | Labels every number as the specification’s, a data sheet’s, an AFS register value or an example input, and does not carry a number from one document to another. |