Article 2.0.2 of general code for waterproofing of building and municipal engineering (GB 55030-2022) specifies the working life of waterproofing design of building and municipal engineering. The design working life is the durability requirement of Engineering waterproofing. During the implementation of the project, how to control the quality of waterproof materials, the guarantee of construction conditions, the selection of construction processes and methods, the quality control of the construction process, the quality acceptance of waterproof layers, the protection of finished products in the waterproof process and other implementation links to meet the requirements of the design working life, with reference to the engineering waterproofing assurance insurance system gradually implemented and improved in the 1980s in Western industrialized countries such as Europe, America and Japan, to promote the establishment of the engineering waterproofing quality assurance mechanism, the implementation of the warranty period system in the engineering waterproofing quality management, and the establishment of the entry threshold for bidding and tendering are the key to eradicate leakage and meet the design requirements.

1. Concept of waterproofing quality guarantee period system

The foreign waterproofing project quality guarantee period system (hereinafter referred to as the guarantee period system) was implemented from the late 1970s to the early 1980s. Before that, there was also a serious problem of building leakage. The causes of leakage lie in construction, materials, design, etc., and improper waterproof construction is the most important factor causing leakage, which is also the main reason for the implementation of warranty period system in foreign countries. Strict regulations force professional waterproofing construction companies to improve and improve project quality from the perspective of construction technology, otherwise they will not only bear economic losses, but also lose credibility and go bankrupt. As the implementation of the guarantee period system has effectively solved the problem of water leakage, some developed countries continue to implement and improve the guarantee period system. Developed countries such as Europe, the United States and Japan have implemented the warranty period system, while China currently implements the five-year warranty period system. Warranty period and warranty period are two completely different concepts. The warranty period system refers to that if the waterproof works are damaged due to non-human reasons and cause leakage within the specified warranty period, the construction unit shall be responsible for repairing and bear all costs incurred. In other words, it is normal for water leakage to occur within the time specified in the warranty period, and repair after leakage is allowed. The guarantee period system means that no water leakage is allowed within the specified time. Leakage is a quality accident of the project. In addition to the maintenance, the construction unit shall also compensate for all losses caused by water leakage, such as damage to interior decoration, damage to furniture, equipment and facilities, and loss due to shutdown. This compensation is guaranteed by law and implemented by the insurance company.

2. Necessity of implementing guarantee period system

Water leakage is one of the main common quality problems in architecture and municipal engineering. The market is flooded with low-quality materials, fake and shoddy materials, the cost of waterproofing works is low, and the phenomenon of Jerry building is serious. Designers do not pay much attention to waterproofing design, or even do not understand waterproofing common sense. When selecting materials, they do not take into account the use, environmental and climatic characteristics, and waterproof part structure of waterproofing works. There is a lack of professional waterproofing construction enterprises. The construction is not standardized, the management is not strict, and the construction personnel work without training. The professional quality and technical level are low, and the maintenance management has not received due attention.

(1) Implementing the guarantee period system can better implement the national standards and norms

In order to ensure the quality of waterproofing works, the general specification has made comprehensive provisions on materials, design, construction, management and maintenance, as well as the working life of waterproofing design of the project, during which no leakage is allowed. The essence of the design working life is the guarantee period. It is not enough to implement the specifications by themselves. It must be constrained by the legal system, that is, it must be constrained by the quality guarantee period system.

(2) The implementation of guarantee period system can promote the development of high-quality materials

High quality waterproof material is the basic condition to ensure the quality of waterproof engineering. The project quality is not required and the leakage is not responsible, resulting in the flooding of the market with fake and shoddy materials, and the non-standard waterproof materials occupy a dominant position. With the implementation of the guarantee period system, the person in charge of project quality will select the best and discard the inferior according to the quality first, and there will be no market for low-grade, fake and inferior materials. Material manufacturers will also produce high-quality materials to participate in the competition, so as to promote the development of high-quality materials.

(3) Implementation of guarantee period system can promote the development of waterproofing technology

To ensure the quality of waterproofing works, it is necessary to develop new waterproofing technologies. The new waterproofing technology is a complete set of comprehensive technologies including new waterproofing materials, new application technology, new waterproofing design, new construction machines and tools and new management technology. Only by carrying out all-round control and using the guarantee period system to restrict, can the overall level of waterproofing technology be improved.

(4) The implementation of the guarantee period system can put an end to wrangling and improper transactions

The general specifications put forward requirements and constraints for materials, design, construction, quality acceptance, maintenance and other links. In fact, when a building leaks, the material manufacturers, waterproof construction units, design departments, etc. pass the buck, and none of them will bear the responsibility. It is quite difficult to coordinate and unify the several companies and assume their respective responsibilities. The implementation of the guarantee period system, the implementation of a single contractor system, and the identification of the ultimate responsible person for the project can put an end to the wrangling and unfair transactions.

(5) The quality of waterproofing works can only be guaranteed by implementing the guarantee period system

The guarantee period system is an effective economic lever and a legal constraint. Implement the guarantee period system. If the building leaks, the responsible person must be responsible for repairing it, and compensate for all the economic losses caused by it. In addition, it will lose its reputation. Therefore, the undertaker of the guarantee period system has to require reasonable design, careful material selection, careful construction and strict management to ensure that the waterproof works do not leak during the guarantee period.

3. Possibility of implementing guarantee period system

According to China's national conditions, with the progress and development of waterproof engineering technology, the possibility of implementing the guarantee period system has become mature and the conditions have been met.

(1) Basically sound quality management laws and regulations

The competent departments of governments at all levels have put the improvement of the quality of waterproofing projects on an important position. The Ministry of housing and urban rural development has issued corresponding laws and regulations, defined the quality responsibilities of the five parties, established waterproof material quality management and on-site sampling and re inspection system, waterproof construction professional qualification requirements, project quality supervision and quality warranty system, etc.

(2) The quality of waterproof materials can meet the requirements of warranty period

China has a complete variety of waterproof materials. All kinds of waterproof materials have corresponding material standards for production quality control, which can be used as the basis for sampling and re inspection at the construction site. The quality level of waterproof materials in China can meet or approach the requirements of international advanced standards. The service life of waterproof materials that meet the requirements of the standards is more than 15 years, and some can even reach 30 years. Through composite waterproof fortification, various waterproof layer protection and other measures, the requirements for the working life of engineering waterproof design can be fully met.

(3) Engineering waterproof technical basis is gradually improved

China's standards and specifications on waterproofing of buildings and municipal works are basically complete. There are corresponding national or industrial standards for building roofs, basements, exterior walls and interiors that need waterproofing, as well as various underground works, bridges, pools, swimming pools, etc. some provinces and cities have prepared local standards such as technical specifications and standard atlas in the region in combination with local specific conditions, as the basis for waterproofing design, material selection, construction and quality acceptance of the project.

China's proposal on the implementation of the quality assurance period system for waterproofing projects has been demonstrated by the relevant waterproofing associations. The necessity, coverage, operation mode and Prospect of the implementation of the quality assurance period system have been scientifically analyzed and a consensus has been reached. It is of great practical significance to carry out the waterproofing project quality guarantee period system as soon as possible. It can not only improve the quality of waterproofing works by a large margin, but also conform to the specific attributes of building waterproofing works and the laws of market economy. It is conducive to the integration with the international community and the equal competition in the waterproofing market at home and abroad.

The implementation of the waterproof project quality assurance period system should not only stay on the slogan, but also take action. The establishment of a quality assurance period system for waterproofing works with Chinese characteristics is the fundamental method to thoroughly control leakage. Only by issuing relevant policies and regulations as soon as possible can the quality problems of waterproofing works be fundamentally eliminated.

Author Zhang Wenhua

Professor, School of civil engineering, Zhejiang University of Technology