Overview
EN ISO 16536:2019 - Thermal insulating products for building applications: Determination of long‑term water absorption by diffusion - is a CEN-endorsed ISO test method for measuring how much water thermal insulation absorbs when exposed to high relative humidity and a vapour pressure gradient over a prolonged period. The procedure simulates situations such as inverted roofs or unprotected ground insulation where both faces are exposed to near‑saturated vapour conditions. Note: the test is not applicable to all insulation types; applicability is determined by the relevant product standard.
Key topics and technical requirements
- Scope and principle: Measures mass gain due to water vapour diffusion over a 28‑day period under controlled temperature and vapour pressure gradient.
- Apparatus essentials:
- Balance accurate to 0.1 g.
- Corrosion‑resistant container/frame and sealing (sealing width ≤ 10 mm).
- Heating/thermostat to maintain water at (50 ± 1) °C.
- Insulated cooling plate at (1 ± 0.5) °C.
- Tap water at test temperature.
- Test specimens:
- Thickness = original product thickness; square sides (500 ± 1) mm where practicable (smaller if product size limits).
- At least two specimens; cut to avoid original edges and preserve facings/coatings.
- Conditioning: normally (23 ± 5) °C (minimum 6 h); for dispute use (23 ± 2) °C and (50 ± 5) % RH. Tropical option: (27 ± 2) °C, (65 ± 5) % RH.
- Procedure:
- Measure initial mass (m0), expose specimen for 28 days with water at 50 °C below and cooling plate above, weigh and turn every 7 days, then determine final mass (mD).
- Results and calculation:
- Report long‑term water absorption as mass per area (kg/m²) or volume percent using the standard formulas. Round to 0.01 kg/m² or 0.1 vol‑% as specified.
- Reporting: Must include reference to EN ISO 16536:2019, product identification, pre‑test history, conditioning, deviations, dates, all individual values and mean.
Applications and users
- Who uses it:
- Test laboratories performing durability and moisture testing.
- Insulation manufacturers - product development, quality control, and compliance.
- Specifiers, architects and façade/roofing engineers assessing suitability for inverted roofs, ground insulation and other high‑humidity exposures.
- Regulatory bodies and product certification schemes that reference product standards.
- Practical value:
- Predicts long‑term moisture uptake under vapour diffusion conditions.
- Supports material selection for high‑moisture building applications.
- Provides objective data for product standards and performance claims.
Related standards
- ISO 29768 (referenced) - determination of linear dimensions of test specimens.
- EN ISO 16536:2019 supersedes EN 12088:2013; consult the relevant product standard to confirm applicability for specific insulation types.
Keywords: EN ISO 16536:2019, long‑term water absorption, thermal insulating products, diffusion test, inverted roof, ground insulation, water vapour diffusion test.
