House Wrap in the global development process
German architect found in the 1940s, the self-adhesive and sealing characteristics of asphalt waterproof coiled material and coating waterproof material enclosed the residual moisture in the concrete structure. The water vapor in the concrete structure can't send out and lead to roof and wall body mold. The indoor air quality seriously threaten the human health living in the house.So that the German construction field begins to use the roofing mat that has breathable performance replacing the use of asphalt waterproof coiled material and coating waterproof. This kind of breathable mat is directly spread on the roofing base course and make the moisture vapor of the roofing board- a cast-in-place concrete quickly go out avoiding the breed of mould thereby.
Under the historical background of that time, people's understanding of building energy conservation was not enough. In the 1970s, with the outbreak of the world energy crisis, European and American countries paid more and more attention to building energy conservation.Energy experts found that although this kind of breathable cushion makes the water vapor of the cast-in-place concrete roof to be discharged, effectively solving the problem of moisture and mold, but a large number of water vapor was discharged to the insulation layer causing serious damage on the thermal performance of the insulation material.
In the mid-20th century, experts from American and Canadian Building Standards Association found that the condensation of water vapor in building external walls and roofs would seriously affect the performance of building thermal insulation materials and the durability of building envelope, leading to the breeding of mold.The main cause of dampness is the infiltration of liquid phase water and vapor phase water into the enclosure structure with the help of the air outside the building.From then on, some American buildings began to use waterproof film, which was laid on the outside of the insulation layer as the building covering system, to strengthen the air tightness and water tightness of the building. However, this waterproof film is not breathable, and the moisture vapor of the enclosure structure still cannot send out so that it cannot completely solve the problem of moisture-proof.
After continuous scientific research and practice, German and American experts in the field of architecture finally found that the breathable roof cushion should be changed into impermeable rolling material as a vapor barrier which is empty spread on the roof base, so that the water vapor in the cast-in-place concrete roof can discharge outside to a certain extent and slow down the spread of the water vapor from the concrete roof to the insulation layer.Then the waterproof membrane with air permeability is used as the building covering system (later called house wrap), which prevents the infiltration of liquid phase water and vapor phase water outside the building and at the same time makes the water vapor inside the insulation layer discharge out rapidly.The combined use of steam barrier and house wrap strengthens the air tightness and water tightness of the building,so that solve the problem of moisture and mold resistance, and effectively protects the thermal performance of the envelope, thus truly achieve the purpose of energy saving.
At the end of 1980s, house wrap scheme was vigorously promoted in developed countries in Europe and America, and was widely used in residential buildings and public buildings. The construction with house wrap was known as "a breathable house".The house wrap is laid on the insulation layer, which can effectively protect the insulation layer. No need to pour fine stone concrete on the insulation, and the optimization of the scheme reduces the construction cost.Japan, Malaysia and other countries have also introduced German and American technology, and began the mass production and application of house wrap.
In recent years, the Chinese government has paid more and more attention to building energy conservation which makes the house wrap scheme began to be vigorously promoted in China.The government also makes the atlas of "house wrap building structure", "pressed steel plate, sandwich board roof and external wall building structure" and other special ones.