Overview
ISO 29764:2008 defines a standardized laboratory method for measuring the deformation of thermal insulating products used in building applications when subjected to specified compressive loads, temperatures and times. The standard describes the required apparatus, specimen preparation and conditioning, test procedure (two-step exposure under load), calculation of relative deformation and reporting requirements. Keywords: ISO 29764:2008, thermal insulating products, deformation under compressive load, compressive deformation test.
Key topics and technical requirements
- Scope: Applicable to thermal insulating products for building applications; determines deformation under defined compressive stress, temperature and time.
- Principle: Apply a specified compressive load to a specimen and measure thickness reduction in two steps (Step A at ambient-like conditions; Step B at elevated temperature/time).
- Test conditions (example sets):
- Set 1: 20 kPa - Step A: 23 ± 5 °C for 48 h; Step B: 80 ± 1 °C for 48 h
- Set 2: 40 kPa - Step A: 23 ± 5 °C for 48 h; Step B: 70 ± 1 °C for 168 h
- Set 3: 80 kPa - Step A: 23 ± 5 °C for 48 h; Step B: 60 ± 1 °C for 168 h
- Apparatus:
- Dimension instruments to ISO 29768: 0.5% accuracy for length/width and 0.1 mm for thickness.
- Oven with forced air circulation, temperature stability ±1 K.
- Loading device with two flat, finely ground platens; movable platen must be self-aligning and keep static stress change within ±5%.
- Specimens:
- Thickness equal to original product thickness (minimum 20 mm).
- Square specimens (recommended sizes: 50×50 mm to 300×300 mm); side length ≥ thickness.
- Surface flatness/parallellism tolerance: ≤0.5% of side length (max 0.5 mm).
- Conditioning: at least 6 h at (23 ± 5) °C; for disputes use (23 ± 2) °C and 50 ± 5% RH. Tropical option: 27 °C / 65% RH.
- Minimum three specimens per condition unless product standard states otherwise.
- Results:
- Relative deformation = (thickness reduction / initial thickness) × 100%, reported as mean values to three significant figures.
- Accuracy & reporting:
- Interlaboratory data and precision estimates provided; comprehensive test-report items are specified (product ID, conditioning, deviations, individual and mean results).
Applications and users
- Manufacturers of insulating materials for quality control and product development.
- Independent test laboratories and certification bodies for compliance testing.
- Building designers, specifiers and façade/roof system engineers assessing long-term mechanical behaviour of insulation under load and temperature.
- Regulatory authorities and procurement teams requiring standardized performance data for selection and acceptance of insulation products.
Related standards
- ISO 29768 - Determination of linear dimensions of test specimens (referenced for measuring instruments).
- ISO 5725-2 - Accuracy (trueness and precision) of measurement methods and results.
- Other related ISO methods in the thermal insulating products series (e.g., thickness, compression behaviour, density) that together support comprehensive product assessment.
This standard helps ensure repeatable, comparable measurements of compressive deformation for thermal insulating products used in buildings, enabling better product selection, certification and design decisions.
Open preview (PDF)Thermal insulating products for building applications — Determination of deformation under specified compressive load and temperature conditions
