New National Standard GB 45320-2025 for Building Waterproofing Released! Effective from October 1, 2025, Fully Mandatory

Introduction

The State Administration for Market Regulation (Standardization Administration Committee of the People's Republic of China) has issued Announcement No. 46 of 2024, approving and releasing 9 mandatory national standards including 'Classification and Naming Code of Hazardous Materials'. Among them, the national standard 'Technical Specification for Safety and General Performance of Building Waterproofing Materials' GB 45320-2025 has been approved and will take effect on October 1, 2025.

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Key Technical Requirements Overview

The technical requirements of GB 45320-2025 'Technical Specification for Safety and General Performance of Building Waterproofing Materials' are mainly developed around two core dimensions: 'Safety Performance' and 'Durability and Long-term Usability'. All waterproofing materials available on the market must comply with this standard.

Safety Performance Requirements

This section focuses on the impact of materials on human health and public safety.

Flammability Performance:For externally applied waterproofing materials, their fire performance classification shall not be lower than Class B2 as specified in GB 8624.

Hazardous Substance Limits:It is explicitly required that the total lead (Pb) content in waterproofing materials must not exceed 90 mg/kg. This is crucial for protecting indoor and outdoor environmental safety and worker health.

Worksite Safety:For hot-melt application waterproofing materials, the melting point of the adhesive layer must not be lower than 230°C. This effectively reduces the risk of fire during high-temperature construction processes.

Usability and Durability Requirements

This section ensures that waterproofing materials maintain effective performance over long-term use.Sealing Functionality

Bonding Reliability:Clear requirements are set for bonding strength and impermeability after exposure to heat aging, water immersion, and other treatments. The material must retain its performance characteristics after such aging processes.

Long-Term Durability:1. Low-Temperature Flexibility After Heat Aging: Performance changes after long-term use must be evaluated. The loss of low-temperature flexibility after aging must not exceed the specified limit. 2. Accelerated Artificial Weathering: For external waterproofing materials with a design service life of no less than 20 years, strict accelerated weathering tests must be conducted to meet cumulative UV exposure requirements, and there must be no visible defects. This is particularly critical for high-performance systems like single-ply membrane roofing. 3. Water Resistance: Depending on different application scenarios (e.g., underground engineering), specific requirements are defined for water absorption rate or surface appearance change after immersion.

Special Functional Certification:Root-Resistant Waterproofing MaterialsMust pass root penetration resistance testing. For root-resistant waterproofing materials, the type and concentration of chemical root inhibitors added must be clearly indicated to ensure their effectiveness.

GB 45320-2025 'Technical Specification for Safety and General Performance of Building Waterproofing Materials' is under the jurisdiction of the Ministry of Industry and Information Technology, and is managed by the National Lightweight and Decorative Building Materials Standardization Technical Committee.National Lightweight and Decorative Building Materials Standardization Technical CommitteeOrganized and promoted by the Building Waterproofing Materials Technical Committee (TC195/SC1). Responsible entities include China Building Materials Testing & Certification Group Co., Ltd. (Jiangsu), China Building Materials Jiangsu Waterproofing Research Institute Co., Ltd., China Building Waterproofing Association, and Building Materials Industry Technical Supervision Research Center, among others. The standard specifies detailed requirements regarding product flammability, softening point, total lead, application performance, heat aging resistance, weathering resistance, water resistance, root resistance, types and concentrations of chemical root inhibitors, and testing methods. It is used in conjunction with the current national standard 'General Specifications for Waterproofing in Building and Municipal Engineering' GB 55030-2022, providing essential technical support for the production and application of building waterproofing materials.