Isolation Joint

Isolation Joint

Design Width

12–25 mm

Function

Separates two different elements (e.g., slab–column)

Material

Neoprene sheet + PU sealant

Movement

Differential

Typical Application Detail

Between dissimilar materials

Typical Locations

Around columns, ramps, machine bases

Waterproofing Approach

Compressible filler + PU sealant edge

1. Introduction

Isolation joints separate two dissimilar materials or structural elements (e.g., column–slab, wall–floor) to prevent stress transfer due to differential movement.

These joints are critical for avoiding cracks and leakage at structural interfaces.

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2. Typical Failures

  • Missing compressible filler board.
  • No edge sealant leading to seepage.
  • Debonding between concrete and sealant.
  • Inadequate gap width or poor compaction.

3. System Requirements

  • Provide physical separation with compressible filler.
  • Apply waterproof edge sealant to prevent ingress.
  • Maintain flexibility and continuity with adjacent systems.

4. Recommended Systems

Joint Width
System
Material
10–35 mm
Filler board + PU sealant
Bitumen-impregnated board / Neoprene

5. Methodology

  1. Install compressible filler before casting concrete.
  2. Trim flush after de-shuttering.
  3. Apply primer and PU sealant over top edge.
  4. Provide watertight continuity with waterproofing system.

6. Performance Parameters

Property
Requirement
Standard
Movement capability
±25%
ASTM C719
Adhesion
≥1.0 N/mm
ASTM C794
Compression recovery
≥90%
ASTM D3575

7. QA/QC Checklist

  • ☑ Correct filler type and thickness
  • ☑ Flush edge finish
  • ☑ Sealant cured
  • ☑ No visible gaps or discontinuities

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Disclaimer

SpecX is an industry initiative & a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.