Overview
ISO 20394:2007 - Thermal‑insulating materials - Determination of freeze‑thaw resistance defines a laboratory test method to assess how repeated freeze‑thaw cycling affects the moisture content and mechanical (compressive) properties of thermal‑insulation products. The procedure simulates exposure from dry cold conditions (−20 °C) to wet warm conditions (+20 °C), with freezing in air and thawing in water, over 300 successive cycles. The standard is intended for insulation frequently exposed to water and low temperatures (e.g., inverted roofs, unprotected ground insulation) but is not applicable to all insulation types - applicability is normally indicated in the product standard.
Key topics and requirements
- Test principle: 300 cycles from dry −20 °C (1 h) to wet +20 °C (1 h) with freezing in air and thawing by immersion in water.
- Linked water‑absorption methods: used together with either ISO 20393 (water absorption by diffusion) or ISO 2896 (total immersion); the product standard indicates which to use.
- Apparatus:
- Cold chamber at (−20 ± 2) °C
- Water tank at (20 ± 2) °C with specimen holder
- Precision balance (0.1 g resolution)
- Compression‑testing machine (per ISO 20392)
- Test specimens: square cut, original product thickness; side length (500 ± 1) mm or (200 ± 1) mm depending on water‑absorption method. Specimens must retain skins/facings and be conditioned at (23 ± 5) °C for at least 6 h.
- Measurements & calculations:
- Water absorption expressed as percent by mass or volume (Wm, Wv)
- Changes in compression strength/stress in wet and dry conditions (Δσ) relative to original product values
- Results reported as mean values with specified rounding rules
- Reporting: full test details, specimen identification, procedure deviations, individual and mean results, and visual observations (e.g., cracks, blisters).
- Notes: precision statement was not included in this edition; common drying conditions (examples) are provided in the standard.
Applications and users
ISO 20394:2007 is used by:
- Manufacturers of thermal‑insulation materials to validate durability under freeze‑thaw exposure
- Independent testing laboratories performing product certification and quality control
- Specifiers, architects and roofing professionals assessing suitability of insulation for inverted roofs, below‑grade or unprotected ground applications
- Standards committees and product developers defining product standards and acceptance criteria
Related standards
- ISO 20393 - Rigid cellular plastics: water absorption by diffusion
- ISO 2896 - Rigid cellular plastics: water absorption by total immersion
- ISO 20392 - Rigid cellular plastics: long‑term compressive creep and compression testing procedures
Keywords: ISO 20394:2007, freeze‑thaw resistance, thermal‑insulating materials, water absorption, compression behaviour, freeze‑thaw test, inverted roof insulation.