Summary of the reasons for the fall of the external insulation system

Analysis of the Reasons for the Falling-off of Traditional External Thermal Insulation System

1. Primary structure factors

(1) Uneven settlement damage. Near the expansion joints of longer and larger building structures, it is easy to cause the insulation layer to hollow or partially fall off.

(2) Masonry deformation of frame structure. The outer wall of the frame structure is at the joints of the concrete beams and columns and the masonry, which is prone to damage to the insulation layer caused by the deformation of the masonry.

(3) The openings of the scaffolding are not solidified, and the local base layer of the thermal insulation layer is not strong and damaged.

(4) The external wall decoration components are not firmly fixed and displaced, resulting in a push-pull effect, resulting in partial hollowing of the insulation layer, long-term water seepage after cracks, hollowing or partial shedding.

2. Insulation structural layer factors

(1) Insulation layer of insulation board. The leveling mortar and the main wall hollowing, especially for long-term water seepage, are prone to continuous hollowing expansion, causing the insulation layer to hollow or partially damage; the surface of the insulation board is too loaded, and the insulation layer is easily peeled off directly; The use of wind pressure resistance measures is unreasonable, and it is very easy to cause certain insulation panels to be damaged by wind pressure and hollow or fall off; the architectural decoration model structure forms a large stress structure with the surrounding structure and cracks, hollows, long-term water seepage, and freezing Swelling, etc., forming a hollow drum or falling off over time.

(2) Insulation layer of slurry material. The wall interface is improperly treated. After the wall is treated with interface mortar, the slurry insulation material is applied. Otherwise, the insulation layer will be directly hollowed or the interface treatment material will fail, forming the interface layer and the main wall hollow, and the insulation layer hollowing together ; The insulation layer is not effectively restrained and the load is damaged. If the surface load of the insulation layer is relatively large, the insulation layer should be effectively restrained to disperse the load.

3. Performance factors of insulation materials

(1) Insulation board: The density of the insulation board is too low, and a large amount of recycled materials are mixed in during production or the powder is severely powdered, causing the insulation board and the main wall to form a "false stick" or its own "bone and bones" and partially hollow and fall off; Excessive self-stress, coupled with unreasonable pasting methods or expansion and contraction factors, forms negative wind pressure and causes partial hollowing or damage to the insulation board.

(2) The surface of the insulation board is smooth, the adhesion is poor, and the bonding strength between the insulation board and the bonding mortar is low. The peeling surface appears on the interface between the insulation board and the bonding mortar layer and the surface mortar layer. A typical example is XPS As shown in the video above, the external thermal insulation material used in this building is the XPS board with poor surface adhesion.

(3) Insulation slurry: The quality of insulation materials is unqualified, it is easy to cause poor bonding or long-term failure to cause hollowing; the rubber powder is stored for too long or is damp and initially sets to make it invalid, and the bonding strength is reduced during use.

4. Supporting product factors

(1) Insulation board bonding glue and other supporting products: bonding glue and anchor nails directly affect the bonding firmness of the insulation layer, which is also the main reason for the current quality problems of external insulation projects. Adhesive mortar types are mixed, which cannot meet the reliability requirements of bonded insulation boards; unreasonable gradation of mortar causes comprehensive performance degradation; unreasonable selection of anchor nails may cause potential hollowing, displacement or falling off.

(2) Slurry insulation materials supporting products: when the slurry insulation layer is tiled or combined with the insulation board, the connection between the steel mesh and the main wall is improperly selected to form an invalid connection. According to different walls, special nylon steel nails and other supporting products with reliable connection effect should be used.

5. Construction factors

(1) Factors affecting the construction of the slurry insulation layer: improper treatment of the base wall, such as when the clay brick wall is not sprayed and moistened with water in advance, or when the surface oil and other attachments are not cleaned, the coating area is too large or the speed is too fast. Partial hollowing caused by compaction; unreasonable gradation of slurry insulation materials on site will affect the bonding strength, resulting in potential defects such as partial hollowing or damage during construction; incorrect application methods can easily cause partial hollowing; construction in violation of operating regulations Partial hollowing.

(2) Construction factors for bonding thermal insulation board: In the point bonding method, when the bonding area is less than 30%% and there is no anchor fixation, a potential hollow drum loosening hazard is formed; in the strip bonding method, the size of the glue groove part is too large. Small but dead, full-bonded or thermal insulation board joints are glued to death, resulting in drainage, poor exhaust, and expansion and contraction stress causing internal pressure peeling hollow; when nailing bonding, the bonding glue is too thin and sticky Immediately after the connection, the pressure of the anchor nails is too large, which will cause the insulation board to "deform and open the glue" to falsely bond, and the anchor nails will form an invalid connection with the wall, which may cause potential damage; human factor influence: irresponsible use during construction. The phenomenon of "flower sticking" in the application of glue; forced construction without protective measures in low temperature or rain or snow, so that the bonding layer is immersed in water or frozen, and changes in performance may cause hidden dangers.

6. Other influencing factors

(1) After the construction of the insulation layer, the construction and installation of other work types such as doors and windows, air conditioners, downpipes, etc. caused man-made damage.

(2) The place where the sealant should be applied is not sealed, and the insulation layer is immersed and frozen for a long time.

(3) Other man-made impacts during decoration construction.

The above factors will directly or indirectly damage the bonding insulation layer and the slurry insulation layer. Although it will not cause serious damage in the short term, the impact must not be ignored for a project with a service life of several decades.