Overview
EN ISO 8339:2005 (ISO 8339:2005) specifies a laboratory method to determine the tensile properties of building sealants by measuring extension to break. The standard defines specimen preparation, conditioning, test procedures and result reporting for sealants used in joints in building construction. It is cited as a European adoption of the ISO document and supersedes EN 28339:1990.
Key topics and technical requirements
- Scope: Method for determination of tensile properties (extension to break) of sealants for building joints.
- Specimen preparation: Sealant is placed between two parallel substrates (mortar, anodized aluminium or glass) using spacers (12 mm × 12 mm) and an anti-adherent backing (e.g., PE film). Manufacturer instructions (primers, mixing) must be followed.
- Apparatus:
- Tensile test machine with recording device capable of 5.5 ± 0.7 mm/min extension rate.
- Refrigerated enclosure for −20 ± 2 °C tests.
- Oven (70 ± 2 °C) and container for distilled water for conditioning cycles.
- Conditioning:
- Method A: 28 days at (23 ± 2) °C and (50 ± 5) % RH.
- Method B: Method A followed by three heat/water cycles (oven at 70 °C and immersion in distilled water at 23 °C) to simulate thermal and moisture influence.
- Test temperatures: Tests conducted at (23 ± 2) °C and (−20 ± 2) °C, three specimens per temperature.
- Measured parameters:
- Secant modulus (σ) at a chosen elongation, calculated by σ = F / s (force divided by initial cross-sectional area).
- Elongation at break (%), expressed to the nearest 5%, calculated from final and original specimen widths.
- Output: Force/extension curves recorded until rupture; the report must include secant moduli, elongations at break, type of failure (adhesion/cohesion), conditioning method and other test metadata.
Applications and users
- Practical uses:
- Performance assessment of sealants for façade joints, window and door perimeters, expansion joints and general building sealing.
- Comparative testing during product development, quality control and specification compliance.
- Evaluating low-temperature performance and effects of heat/water exposure on tensile behaviour.
- Who should use this standard:
- Sealant manufacturers, R&D and quality laboratories.
- Building envelope designers, façade engineers and specifiers.
- Third‑party testing bodies and certification organizations.
Related standards
- ISO 8340 - tensile properties at maintained extension (alternative method).
- ISO 13640 - specifications for test substrates.
- ISO 6927 - vocabulary for sealants and jointing products.
Keywords: EN ISO 8339, ISO 8339:2005, sealants tensile properties, extension to break, building construction, tensile test, secant modulus, elongation at break, conditioning.
