Overview
EN ISO 21265:2024 (identical to ISO 21265:2021) defines a laboratory test method for assessing fungal growth on building and civil engineering sealant surfaces. Adopted by CEN in May 2024, this standard specifies procedures to evaluate whether sealants used in joints and façades resist colonization by common fungal species under controlled humidity and temperature. The standard supports product performance assessment, quality control and durability evaluation for sealants exposed to high-humidity service conditions.
Key topics and technical requirements
- Scope: Method for evaluating fungal growth on sealant surfaces used in building construction joints.
- Test organisms: The procedure targets the five commonly encountered fungal strains (examples given in the standard): Fusarium oxysporum, Aspergillus niger, Phoma herbarum, Exophiala jeanselmei, Penicillium chrysogenum (specified by culture collection accession numbers such as ATCC strains).
- Apparatus & conditions: Requirements include incubators (20–35 °C, ±1 °C) with ≥90% relative humidity, ovens (45 ±2 °C), autoclave sterilization (120 ±2 °C, 2 bar), centrifuge, stereomicroscope (×50), analytical balance and sterile Petri dishes.
- Specimen preparation: Conditioning, cleaning, labelling and optional water-immersion steps are specified to simulate service conditions.
- Test procedures: Inoculation methods, spore suspension preparation, viability checks, incubation and arrangement of specimens are detailed to ensure reproducible fungal exposure.
- Assessment & reporting: Visual assessment of fungal growth, measurement of inhibition zones (if any), recording of results and required test-report content are specified for consistent interpretation.
Applications and practical value
- Product development and R&D: Screen formulations for fungistatic/fungicidal properties during formulation and accelerated ageing.
- Quality control and type testing: Verify batch-to-batch consistency and confirm performance claims regarding microbial resistance.
- Specification and procurement: Provide objective test evidence for material selection in high-humidity environments (bathrooms, kitchens, façades, tunnels).
- Compliance and risk mitigation: Support performance-based specifications and help reduce biological staining, odour and material degradation in buildings.
Who should use this standard
- Sealant manufacturers and R&D labs
- Independent test laboratories and certification bodies
- Architects, specifiers and façade engineers
- Building owners, facility managers and contractors concerned with durability in humid conditions
- National standards bodies and regulatory authorities
Related standards
- ISO 846 - Plastics: evaluation of the action of microorganisms (referenced)
- ISO 6927 - Building and civil engineering sealants: vocabulary (referenced)
- EN adoption noted as EN ISO 21265:2024
Using EN ISO 21265:2024 helps stakeholders produce reproducible, comparable fungal resistance data for sealants - essential for durable, hygienic and low-maintenance building joints.