ISO 20492-4:2010

Overview

ISO 20492-4:2010 - "Glass in buildings - Insulating glass - Part 4" defines laboratory test methods for the physical attributes of edge seals used in insulating glass units (IGUs). It is part of the ISO 20492 series that addresses durability, gas leakage and related performance of insulating glass. ISO 20492-4:2010 focuses on edge seal strength, partial assessment of moisture vapour transmission, and gas permeation testing of sealants. The methods are applicable to approach 2 markets (e.g., Europe) and note additional requirements where edges are exposed to UV (structural glazing).

Key technical topics and requirements

• Edge seal strength (adhesion/cohesion testing):
  • Tensile tests on glass–sealant–glass joints after conditioning and ageing.
  • Specimen shapes and preparation are specified (see Annex A); seven joints per exposure condition are required.
  • Failure criteria are based on extension of adhesion/cohesion loss into a defined zone (stress/strain triangle).
• Moisture vapour transmission rate (MVTR):
  • Methods and definitions for measuring steady-state moisture flow through sealant membranes (θ).
  • MVTR results are used to assess suitability and for sealant substitution limits.
• Gas permeation tests on film:
  • Methods to assess gas permeation properties of sealant materials (relevant for gas-filled IGUs).
• Substitution rules for sealants and coated glass:
  • Conditions where a sealant or coated glass can be substituted without repeating full climate tests are specified (e.g., I-value thresholds, MVTR and gas-permeation limits such as ±20 % or specified absolute ranges).
• Test reporting and normative annexes:
  • Clause 6 lists required test report content.
  • Annexes cover specimen details (A), substitution comparisons (B), MVTR measurement method (C), coatings (D), informative tests and UV simulation (E–F).

Practical applications and users

• Target users:
  • IGU manufacturers, product validators, test laboratories, facade engineers, building regulators and specifiers in markets using approach 2 (Europe).
• Practical uses:
  • Verifying sealant system durability and adhesive/cohesive strength.
  • Assessing moisture and gas barrier performance for energy and longevity of IGUs.
  • Supporting material substitutions and factory production control documentation.
  • Demonstrating conformity when CE marking or meeting regional technical specifications.

Related standards

• ISO 20492-1: Durability of edge seals by climate tests
• ISO 20492-3: Gas concentration and gas leakage
• ISO 9050: Glazing optical and solar properties
• EN 1096 (all parts): Coated glass

Keywords: ISO 20492-4, insulating glass, edge seal strength, adhesion test, moisture vapour transmission, gas permeation, sealant testing, insulating glass units.