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Sealants, compatibility and joint design · Lesson 3 of 4

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.

10 min · 11 slides · 6 questions

All lessons in this module
Slide 1 of 11

The sealing sequence

This order follows the public sample specifications.

  • Read the section and data sheet.
  • Check width, temperature and dryness.
  • Clean the faces; mask beside the joint.
  • Apply primer before installing the backer rod or bond-breaker tape.
  • Place the rod or tape at uniform depth.
  • Gun, fill, tool; remove the masking.
  • Pull-test and log it.
The sealing sequence from reading the section to the logged pull testA vertical flow of ten steps in four phases: check, prepare, install and verify, from reading the section and data sheet to pull-testing and logging.Read the section and data sheetCheck compatibility and widthCheck temperature and drynessClean the faces; remove solventMask beside the jointPrime, only if requiredRod or tape to uniform depthGun in and fill solidTool; unmask (UFGS: 10 min)Pull-test and log itCheckPrepareInstallVerifyAny no: stop and ask the specifier.

A vertical flow of ten steps in four phases: check, prepare, install and verify, from reading the section and data sheet to pull-testing and logging.

The order follows the public sample specifications. Your project section and the data sheet may add steps.

Sources

Glossary

Primer
A liquid applied to joint faces where the sealant maker requires it or a test shows it is needed. Apply it before the backer rod or bond-breaker tape; never on exposed finished surfaces.
Hourglass profile
A joint shape where the sealant is thinner at its center than at the bond faces: the sample VA specification asks for center thickness about half the depth at the adhesion surface.
Movement (each way)
How far the joint opens and closes from its width at sealing. The class number is read against it, as a percentage of that width.
Masking tape
Non-staining tape placed beside a joint to keep primer and sealant off finished surfaces; removed within 10 minutes of filling and tooling in the sample UFGS, and before the sealant skins over in the sample VA specification.
Closed-cell backing
Backing with a closed skin, which the sample VA specification names and which must not be punctured. The sample UFGS asks for it to be 25 to 33 percent oversized.