What is building waterproofing

Material and structural measures taken to prevent the penetration of water into certain parts of a building. Waterproofing is mainly used in roofing, underground buildings, underground parts of buildings and inner rooms and water storage structures that need to be waterproofed. According to the different measures and means taken, it is divided into material waterproof and structural waterproof two categories. Material waterproofing is to block the passage of water by building materials to achieve the purpose of waterproofing or increase the ability to resist leakage, such as coil waterproofing, film waterproofing, rigid waterproofing of concrete and cement mortar, and waterproof of clay and lime soil. Structural waterproofing is to adopt a suitable structural form to block the passage of water to achieve the purpose of waterproofing, such as water stop belt and cavity structure.

Building waterproofing is a defensive measure taken to avoid the harm of water to the building, such as the outer envelope structure and the basement. Including waterproof construction treatment and waterproof material selection.
There are two common waterproof construction methods: structural waterproof and material waterproof. Structural waterproofing is to achieve the purpose of waterproofing by using the shape and overlap of the component itself, which is mainly used for the self-waterproofing roof of the component and the joint of the outer wall panel of the prefabricated building. Material waterproofing is the use of material impermeability to cover and seal components and gaps. Often used for roof, exterior wall, basement and other places waterproof.
There are many types of waterproof materials, mainly asphalt, plastic and rubber and waterproof concrete. Asphaltene waterproof coil is widely used in underground, hydraulic, industrial and other buildings. Plastic and rubber waterproof materials include films, coatings, waterproofing agents, caulking sealing materials, etc. Waterproof concrete is mainly used in underground water construction and roofing engineering.

Ancient waterproofing technique
The practice of ancient Chinese waterproof layer commonly used clay or clay mixed with lime, that is, lime soil (see lime soil foundation), plus glutinous rice porridge pulp and kiwi fruit (that is, sheep peach) rattan juice mixed, sometimes also mixed with animal blood, iron red, etc., layered rammed composition. This method is a unique technology commonly used for waterproofing projects such as underground mausoleums or storage tanks in ancient China. As the strength of lime soil increases with time, its ability to prevent leakage increases gradually. A tomb unearthed in Huixian, Henan Province, in the third century BC, at the end of the Warring States Period, was filled with a thick layer of sand and charcoal, and the upper layer was tamped with clay. The famous Mawangdui Han Tomb also has a similar structure, indicating that China has had successful waterproof measures long ago. In the roof structure of ancient Chinese buildings, there are lead-tin alloys that are melted and cast into plates about 10 mm thick and welded into a whole, commonly known as "Scylla back" or "tin back", which is a waterproof material used in palace buildings. The Qin 'an Hall in the Imperial Garden of the Forbidden City in Beijing has lasted for more than 500 years and is still intact. During the renovation of the Tiananmen Gate Tower in the early 1970s, a 3-meter-wide and 3-millimeter thick green lead sheet was found on the roof ridge as a waterproof layer. It's a variant of the tin back.

Coil waterproofing
Asphalt and an appropriate amount of powder are heated to make a hot asphalt paste binder (i.e., Ma □ grease), and the linoleum (see waterproof sheet) is layered on the roof, underground buildings, and the internal and external surfaces of water storage structures. This kind of coil waterproof has been used for more than 100 years, and it is a waterproof method used more in flat roofs and basements. Use diesel oil to dilute asphalt, so that Ma grease can be painted at room temperature called cold Ma grease. Coil waterproof roofing usually adopts two felt and three oil or three felt and four oil method, that is, after coating cold bottom oil on the base leveling layer, the Ma grease and the linoleum with certain heat resistance, flexibility and bonding force requirements are alternately laid, and the last layer of Ma grease is sprinkled with dry small bean stone as a protective layer. When used in underground buildings, it is generally only used as an auxiliary measure for moisture-proof or multi-channel waterproof, and a half-brick wall with cement mortar is used as a protective layer. At the intersection of the wall and the bottom plate, the embedded pipe fittings, gutter, parapet, rain hole and other parts are usually laid with 1 to 2 layers of linoleum additional layer. In wet areas or in the rainy season roof construction, in order to prevent the evaporation of water trapped in the insulation layer or leveling layer, the coil drum is often spread on the leveling layer into an exhaust channel, and the exhaust hole is set up on the roof or the eaves to communicate with the atmosphere, so that the water vapor can be discharged smoothly. When the roof is coated with coil material, it should be from low to high, leaving the overlap amplitude layer by layer. When the slope of the roof is small, lay it in the direction parallel to the roof ridge; When the slope of the roof is large, it should be laid in the direction of the vertical ridge, and the joint of the lap should follow the dominant wind direction. The thickness of the Ma grease is 1 ~ 1.5 mm in roofing projects and 1.5 ~ 2.5 mm in underground construction projects. In the joint part of the roof plate without insulation layer, it is appropriate to lay a dry felt strip with a width of not less than 300 mm on the bottom of the linoleum to prevent the main linoleum layer from pulling apart due to structural deformation. Elastic waterproof coil is mostly made of synthetic rubber. It has good elasticity, high strength, durability, simple construction, and can adapt to the temperature of -40 ~ 100°C. In 1982, China developed vulcanized rubber plastic waterproof coil, which has been used as a waterproof layer of Beijing Great Wall Hotel pool (see color picture of Beijing Great Wall Hotel pool paved with rubber plastic coil waterproof layer), the effect is good.