Thermal insulation — Mineral wool board for overdeck insulation of roofs — Specification

Background and Technological Innovation of ISO 8145:2026 Standard

ISO 8145:2026, the second edition of the standard published by the International Organization for Standardization, replaced the first edition in 1994, marking a significant upgrade in the technical specifications for mineral wool boards used in roof external insulation. This revision was led by ISO/TC 163/SC 3 (Technical Committee on Thermal Performance and Energy Use in Buildings/Subcommittee on Insulation Products, Components and Systems), reflecting the progress made in building materials science, testing methods, and quality control systems over the past thirty years.

The technical revisions to the standard mainly focus on two key areas: **standardization of dimensional testing methods** and **modernization of thermal conductivity and thermal resistance testing procedures**. These changes reflect the industry's increasing demands for product accuracy and performance predictability, especially in the context of increasingly stringent global building energy efficiency regulations, which place higher demands on the reliability and comparability of insulation material performance data.

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Scope of Application and Product Definition

This standard specifically addresses bonded artificial mineral wool boards for overdeck insulation of buildings, clarifying its scope of application as roofs intended for maintenance personnel only. Product forms include boards with or without a surface layer, but the waterproofing performance of the surface layer itself is not within the scope of this standard. The standard emphasizes that even with a surface layer, the product itself does not possess waterproofing functionality, providing clear guidance for designers to correctly understand the functional boundaries of the product.

It is worth noting that the limits provided in the standard are primarily for regulatory purposes; actual design values must consider the impact of environmental factors and installation processes on the product's thermal performance. This distinction reflects a shift in standard development from simply specifying product specifications to a performance-oriented design mindset.

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In-depth analysis of key technical requirements

5.1 Dimensional tolerance system

The standard establishes a comprehensive dimensional tolerance control system, requiring manufacturers to declare nominal dimensions and verify them through the ISO 29465-29468 series of standards. Tolerance requirements reflect the importance placed on construction and installation precision:

Dimensional parameters	Allowable deviations	Test standards	Engineering significance
Length (l)	±5mm or ±1% (whichever is greater)	ISO 29465	Ensuring panel joint control
Width (b)	±5mm (average value of a single sample)	ISO 29465	Affecting coverage and material usage
Thickness (d)	±3mm (average value of all samples)	ISO 29466	Directly affects thermal performance calculation
Squareness	Longest face per 1000mm ≤ 3mm	ISO 29467	Affects installation quality and appearance
Flatness	Maximum deviation ≤ 0.40% of length or width	ISO 29468	Prevent water accumulation and ensure smooth drainage

5.3 Thermal Performance Declaration Specification

Thermal performance declaration is the core content of this standard, and a strict statistical declaration system has been established.

Manufacturers must declare thermal resistance R_D or thermal conductivity λ_D according to the following rules: Reference average temperature: Must be declared at 10°C or 23°C, or both. Statistical assurance level: The declared value must represent at least 90% of manufactured products with a 90% confidence level. Rounding rules: Thermal conductivity is rounded up to 0.001 W/(m·K), and thermal resistance is rounded down to 0.05 m²·K/W. Thickness treatment: Thermal resistance must be declared for products with uniform thickness; thermal conductivity is declared only for products with non-uniform thickness. This declaration system ensures the comparability of performance data from different manufacturers, providing designers with a reliable basis for selection. Appendix B details the calculation method for the declared value, requiring it to be based on at least 10 test data points using a 90/90 tolerance interval statistical method.

5.4-5.6 Mechanical Performance Requirements

The standard sets clear minimum requirements for the mechanical performance of mineral wool boards. These requirements are directly related to the installation performance and service life of the product:

Performance Indicators	Test Conditions	Limit Requirements	Engineering Significance
Deformation Resistance	24 hours under 20kPa load at 23°C	Average deformation ≤10%	Ensuring thickness stability under long-term load
High Temperature Deformation	24 hours under 20kPa additional load at 80°C	Additional deformation ≤5%	Verifying dimensional stability under high temperature environment
Interlaminar Strength	ISO 29765 Test Method	≥7.5 kPa	Prevent delamination, ensure structural integrity
Breaking Load	Appendix A Three-Point Bending Test	Bidirectional ≥80 N	Ensure load-bearing capacity during installation and maintenance

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Quality Control and Conformity Assessment System

4. Sampling and Conformity Control

The standard requires that conformity control must be carried out in accordance with ISO 12576-1, and the manufacturer needs to declare the selected control options. This framework requirement provides flexibility for companies of different production scales while ensuring the scientific nature of the quality control system.

7. Test Report Specifications

The test report must include 14 mandatory items, from basic product information to statistical analysis of test results, forming a complete traceability system. The laboratory is specifically required to:

• Provide maximum and minimum value data
• Explain the terms on which the result calculation method is based
• Compare and evaluate the test results with the manufacturer's statement and standard requirements
• Give a statement of conformity to this standard

Appendix A: Fracture Load Test Method

Appendix A details the fracture load test method, using a standard testing machine and cylindrical support rollers for a three-point bending test. Key parameters include:

• Specimen size: 300mm × 150mm × full plate thickness
• Support span: 250mm (for plate thickness ≤ 50mm) or 5 times the plate thickness (for plate thickness > 50mm)
• Loading rate: 10mm/min
• Number of specimens: 6 (3 in the forward direction, 3 in the transverse direction)

This method simulates the concentrated loads that the plate may bear during installation and maintenance, providing a standardized basis for evaluating the mechanical strength of the product.

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Standard Implementation Recommendations and Industry Impact

Manufacturer Implementation Recommendations

1. Establish a Comprehensive Quality Control System: Establish a factory production control system according to ISO 12576-1 to ensure quality control throughout the entire process from raw materials to finished products.
2. Thermal Performance Data Management: Establish a dataset of at least 10 test data points, and regularly update the declared values according to standard requirements. It is recommended to recalculate every three months.
3. Dimensional Accuracy Control: Invest in advanced cutting and forming equipment to ensure that product dimensional tolerances consistently meet the requirements of Table 1.
4. Testing Capacity Building: Establish an internal laboratory or cooperate with a certified laboratory to ensure that all necessary tests can be performed according to standard requirements.

Designer Application Guidelines

1. Correct Understanding of Declared Values: Recognize that the manufacturer's declared R_D or λ_D values are statistically guaranteed values, and a safety factor should be considered in actual design.
Environmental Factors Consideration: Adjust thermal performance calculations according to the actual operating ambient temperature; the 10°C and 23°C data provided in the standard can be used as benchmarks.Installation Process Influence: Consider the impact of the installation process on the final thermal performance in the design, and reserve appropriate performance margins.Verification Testing Requirements: Explicitly require suppliers to provide test reports compliant with ISO 8145:2026 in the project specifications.

Precautions for Testing Agencies

1. Unified Testing Methods: Strictly follow the test methods referenced in the standard, especially for thermal performance testing, which must use the heat flow meter method or protective hot plate method.
2. Data Rounding Specifications: Strictly adhere to the rounding rules in the standard, rounding thermal conductivity upwards and thermal resistance downwards.
3. Report Integrity: Ensure the test report includes all 14 items required in Chapter 7 of the standard.
4. Application of Statistical Methods: Correctly apply the statistical methods in Appendix B to calculate the 90/90 tolerance interval.

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Technology Development Trends and Standard Outlook

The release of ISO 8145:2026 reflects several development trends in mineral wool insulation board technology:

• Performance-Oriented Design: A shift from simple product specifications to a performance declaration system, providing space for innovative products.
• Data-Driven Quality Control: A statistically based declaration system requires manufacturers to establish a comprehensive data management system.
• Life Cycle Considerations: The standard begins to focus on the performance of products throughout their entire service life.
Sustainability Requirements: While there are no explicit environmental requirements, the standard reserves an interface for future inclusion of Environmental Product Declarations (EPDs). Looking ahead, with increasingly stringent building energy efficiency requirements and the emergence of new insulation materials, the ISO 8145 standard may further develop in the following ways: incorporating more environmental performance indicators, expanding its scope to other building components, and introducing digital product information requirements. Industry participants should closely monitor these trends and prepare technically in advance. ISO 8145:2026, as the authoritative international standard for mineral wool roof insulation boards, provides a unified technical language and quality benchmark for the global construction industry. By deeply understanding and correctly implementing this standard, manufacturers can improve product quality and competitiveness, designers can make more scientific product selection decisions, and ultimately promote technological progress and sustainable development throughout the building insulation industry.