In recent years, with the vigorous development of the national economy and construction industry, people have put forward new requirements for the comfort and safety of buildings, especially exterior wall insulation materials , which must not only be heat-insulating and energy-saving, but also waterproof and hydrophobic. The waterproof function of exterior wall insulation materials is mainly achieved through three steps.
The main measures to ensure the exterior wall insulation and waterproof functions:
1. Gradual grading, stress relief, and crack prevention are the correct technical routes for exterior wall insulation and waterproofing
External insulation to prevent cracks is the basis for the success of exterior insulation and waterproofing technology . Therefore, the following principles should be considered to prevent cracks in external insulation:
The thermal insulation effect of external insulation meets the requirements that all structures of the building be in the same temperature environment; each structural layer of the external insulation material system should meet the unified principles of allowed deformation, induced deformation and restricted deformation. ; The external insulation structure should meet the principle of flexible stress release, match the elastic modulus change index of each layer, and the flexible deformation of the outer layer is greater than that of the inner layer; evenly dispersed soft steel bars (metal quadrilateral welded mesh should meet the anti-rust performance, glass fiber mesh Alkali resistance strength retention rate) should meet the service life requirements.
The thermal stress caused by rapidly changing temperature differences is concentrated on the outer surface of the insulation. Solving external insulation cracks should follow the principle of releasing temperature stress and deformation ability. The anti-crack technology of layer-by-layer gradient and flexible stress release can effectively control cracks on the surface of the insulation layer. The structural design points of layer-by-layer gradient, flexible stress release and anti-cracking technical concepts are as follows:
The performance and elastic modulus of adjacent structural layers of the insulation system match and gradually change layer by layer. anti-crack mortar should ensure a certain degree of flexibility to release deformation stress. At the same time, the anti-cracking protective layer uses steel mesh to change the direction of stress transmission and prevent the possibility of various deformation stress concentrations. After the coating is completed, the ideal pattern should be from a crack-resistant mortar layer to a putty layer. The flexibility and deformation ability of the coating gradually increase; when facing ceramic tiles, flexible adhesives and joint adhesives should be used.
In the application of exterior wall insulation technology, the "release" anti-cracking principle is adopted, that is, the anti-cracking technical route of flexible gradient and layer-by-layer stress release is the correct method for exterior wall insulation to not crack and ensure waterproof function.
2. Solve the problem of thermal bridges in exterior walls
Thermal bridges refer to parts of the enclosure structure, including metal, reinforced concrete beams, columns, balconies, sunshades, lines, etc. Under the influence of the temperature difference between indoor and outdoor, components with intensive heat transfer and low surface temperature are formed. These parts form a heat transfer bridge, so they are called thermal bridges. These thermal bridges are usually ignored without insulation, and temperature-induced deformations differ from those in walls with external insulation. After a certain period of deformation and destruction, damage cracks will appear at the intersection between these uninsulated parts and the wall with external insulation. The fundamental way to solve the thermal bridge is to break the bridge, that is, the outer insulation layer must completely cover all outer surfaces to seal the insulation layer. For example, a parapet rising from the roof should have external insulation layers on the front, back and top.
3. Construction measures for bonding layer cavities
In order to prevent rain, snow, and water from entering the insulation layer and flowing around the bonding layer cavity, the point box bonding method must be used in the construction of bonded insulation materials in Chongqing. The four sides of the insulation board should be coated with adhesive mortar, with a width of not less than 5 cm and no more than 1 cm from the outside of the board, so that the adhesive mortar forms a closed frame, and five adhesive mortar points should be applied within the frame. This not only ensures the pasting area, but also allows the compacted pasting mortar to be squeezed to the edge of the board. There is no gap between adjacent boards, blocking the water seepage route.
