ISO 1663:2023

Overview

ISO 1663:2023 specifies a standardized laboratory method to determine the water vapour transmission properties of rigid cellular plastics. It covers measurement of the water vapour transmission rate, water vapour permeance, water vapour permeability and the water vapour diffusion resistance index using a desiccant-based cup method and controlled temperature/humidity environments. Results are intended for design, production control and inclusion in product specifications.

Key topics and technical requirements

• Scope: Applicable to rigid cellular plastics with thicknesses from 10 mm upwards (or manufactured thickness if <10 mm); preferred specimen thickness is 25 mm.
• Measurement range: Suitable for transmission rates from 3 µg/(m2·s) to 1 400 µg/(m2·s).
• Test conditions: Three standardized temperature/humidity sets:
  • 38 °C with 0 % → 88 % relative-humidity gradient (± tolerances)
  • 23 °C with 0 % → 85 % relative-humidity gradient
  • 23 °C with 0 % → 50 % relative-humidity gradient
• Specimens: Minimum exposed area 50 cm²; specimen diameter ≥ four times thickness; minimum five specimens per test. Conditioning per ISO 291 recommended.
• Apparatus: Desiccant cup assembly with anhydrous calcium chloride, sealant wax, analytical balance (accuracy 0.1 mg), and a constant-temperature/constant-humidity chamber (monitoring of temperature and RH).
• Procedure principle: Seal specimen over a desiccant-filled dish, place in controlled environment, and determine the water vapour transmission rate from the linear mass change over time.
• Calculations & reporting: Includes permeance, permeability (permeance × thickness), and the diffusion resistance index. Test precision and reporting requirements are specified.

Applications and who uses ISO 1663

• Manufacturers of rigid cellular plastics and insulation products for validating product performance and ensuring quality control.
• Independent test laboratories performing accredited water vapour transmission testing.
• Product development and R&D teams comparing formulations or facings (skins) for moisture resistance.
• Specifiers, architects and building-envelope engineers including vapour control data in product specifications and hygrothermal design.
• Compliance and procurement teams requiring standardized, comparable water vapour data for material selection.

Related standards

• ISO 291 - Plastics: standard atmospheres for conditioning and testing (conditioning requirements referenced).
• ISO 1923 - Cellular plastics and rubbers: determination of linear dimensions (thickness measurement procedures).

Keywords: ISO 1663, water vapour transmission, rigid cellular plastics, water vapour permeance, water vapour permeability, diffusion resistance index, desiccant cup method, humidity chamber, product specification.