ISO 29767:2019

Overview - ISO 29767:2019 (short-term water absorption, partial immersion)

ISO 29767:2019 specifies a laboratory method to determine the short‑term water absorption of thermal insulating products for building applications by partial immersion. The procedure simulates water uptake caused by a 24‑hour raining period during construction and gives a repeatable, comparable measure of how much water a product absorbs through the immersed face. Results are expressed as mass gain per unit bottom area (kg/m²).

Key topics and technical requirements

• Scope: Applies to thermal insulating products used in buildings; intended to simulate a 24 h rain event.
• Specimens:
  • Prism specimens with square cross‑section, side (200 ± 1) mm; thickness = original product thickness.
  • At least four specimens unless a product standard specifies otherwise.
  • Cut without edges removed; retain skins, facings and coatings.
• Conditioning and test environment:
  • Conditioning: minimum 6 h at (23 ± 5) °C (more stringent 23 ± 2 °C / 50 ± 5 % RH in disputes or as product standard).
  • Test temperature usually (23 ± 5) °C; tropical conditions (27 ± 5 °C and/or 65 % RH) allowed and must be reported.
• Apparatus:
  • Balance accurate to 0.1 g.
  • Water tank with level control (±2 mm) and specimen holder that covers ≤15 % of immersed cross‑sectional area.
  • Tap water at test temperature; deionised water when disputed.
  • Drainage equipment for Method A (e.g., inclined mesh).
• Test methods:
  • Method A (drainage): After 24 h immersion (bottom face 10 ± 2 mm below water), specimen is drained for 10 min and weighed. Water uptake W = (m24 − m0) / Ap.
  • Method B (deduction of initial uptake): Initial short exposure (10 s) measures initial water pickup (m1); after 24 h the specimen is weighed. Applicable only if initial uptake ≤ 0.5 kg/m². Water uptake W = (m24 − m1) / Ap.
  • Results reported to nearest 0.01 kg/m²; mean of individual values used. For products with dissimilar faces, report two means.
• Accuracy:
  • Interlaboratory data: Method A reproducibility ~0.10 kg/m² (range tested 0.02–0.50 kg/m²); Method B reproducibility ~0.15 kg/m² (range 0.04–0.20 kg/m²). Repeatability not determined.

Applications - who uses ISO 29767:2019

• Insulation manufacturers for product development, quality control and specification compliance.
• Independent testing laboratories to provide standardized water‑absorption data.
• Architects, specifiers and building engineers assessing moisture risk during construction and selecting suitable materials.
• Certification bodies and regulators requiring harmonized test evidence for product performance claims.

Related standards

• ISO 29768 (determination of linear dimensions of test specimens)
• ISO 5725‑2 (precision and reproducibility of measurement methods) - referenced for accuracy assessment

Keywords: ISO 29767:2019, thermal insulating products, short‑term water absorption, partial immersion test, Method A drainage, Method B initial uptake, building insulation testing, 24‑hour rain simulation.