1. Quality reasons of raw materials themselves:

1) The temperature difference deformation of window frames and sashes is serious, the products are irregular, the strength is not enough, the diagonal tolerance is greater than 3 mm, and the clearance with the hole is too large, resulting in leakage.

2) After the window frame is installed, the mortar plastered around the hole cannot be permanently combined with the leveling layer of the original basement of the wall, and the coefficient of thermal expansion and cold contraction of aluminum alloy window (or plastic steel window) is relatively large, so the mortar plastering layer on the edge of the window frame will crack, fall off and leak soon after use.

3) Open the sash repeatedly, so that the window frame is subjected to push-pull vibration. Because the periphery of the window is not made of high elastic sealing material, the installed mortar is separated from the original mortar surface, resulting in leakage.

4) The quality of the sliding window sealing strip is poor, and it deforms prematurely and fails under the action of temperature difference, which can't stop the rainwater from penetrating and leading to leakage.

5) The exterior wall tiles on the window sill of the outer window cover are false or even cracked, which leads to rainwater infiltrating around the indoor interior wall along tiny cracks.

6) The periphery of the window frame outside the window is not waterproof and sealed, and only low-grade glass glue is used for joint filling. Glass glue prematurely aged and failed, and rainwater infiltrated into the indoor wall from the outside of the window sill under the action of wind.

2, design, construction and management reasons:

1) The waterproof design of external windows should be based on the principle of "drainage as the premise, waterproofing as the basis, sealing as the key, multi-channel fortification and * * * together", pay attention to reasonable waterproof structure design, and optimize waterproof materials and plastering grades. When necessary, it is necessary to provide instructions, technical disclosure and node construction scheme, so that construction personnel can correctly grasp the operation of key parts. Improper design of waterproof scheme often leads to leakage of external windows, which is difficult to cure in the later stage.

2) The waterproof construction of external windows is not carefully constructed in strict accordance with the operating rules and design requirements, and improper waterproof measures in some places cause poor quality of detail joints, and the sealing effect can not meet the requirements of specifications. The construction of grouting, caulking and punching is not standardized, which is also the cause of leakage.

3) Improper operation technology of external window, failure to carry out management measures such as protection and detection of semi-finished products (finished products) according to relevant requirements, resulting in failure to guarantee waterproof quality of external window, resulting in crack deformation and leakage.

Second, the quality control measures to prevent leakage of external window parts

1, good design.

1) The outer window sill should be waterproof, and the inner window sill should be 20 mm higher than the outer window sill. An outward drainage slope with a slope of not less than 3% should be set on the outer windowsill surface protruding from the wall surface, and the lower part should be dripped, and the corner with the wall surface should be rounded with a diameter of100 mm.

2) Window profiles should meet the requirements, and inferior and unqualified products should not be selected for small profits.

3) When the wall is made of hollow blocks, the masonry within 200 mm around the window of the external wall should be built with solid bricks or blocks, or C20 fine stone concrete should be poured. Masonry blocks should use special mortar with large consistency, especially vertical joints should be filled, and all masonry joints should be marked with protoplasm. Around the humanly scaled opening, polymer cement mortar with a thickness of not less than 5 mm should be embedded, or flexible sealing material should be filled after spraying foam insulation material when installing doors and windows.

4) The strength of external wall mortar should be graded to avoid many leakage channels due to low strength and loose materials.

5) The plastering grade of the external wall should be indicated in the design, instead of simply indicating mortar priming and bricklaying.

6) The waterproof materials and construction methods used within 300㎜ around the window shall be indicated, and node details shall be provided when necessary.

7) In addition, a U-shaped water diversion strip (groove) is installed on the upper edge of each window, so that rainwater can be discharged to the outside of the upper edge of the window to prevent rainwater from flowing back into the window and water from entering the window along the outer edge. Aluminum alloy watersheds should be painted with the same paint as exterior wall finishes, and the width of watersheds (slots) should be 40 cm wider than the outer window cover.

2, to ensure the construction quality

2. 1 construction process

Before construction, the base should be inspected, cleaned and treated, the external window frame and the external wall should be partially enlarged, the key parts should be sealed, the water distributor should be installed, the waterproof agent should be sprayed within 30 cm of the external window frame, the water spraying test should be carried out, and the repair should be reviewed in time.

2.2 construction points

Waterproof works for external windows shall be constructed by waterproof professional team.

1) installation. The reserved hole position of aluminum alloy window should be correct, and the gap between frame and wall should be uniform, controlled at 20 ~ 30 mm

2) Check the window frame joints. See whether the joint shape and size meet the sealing design requirements, and first deal with the joint defects and cracks to be sealed.

3) Joint surface treatment. Rinse the seam between the window frame and the wall with clear water, so as to be dust-free, sand-free, pollution-free and sundries-free.

4) Filling construction with foam sealant. When replacing the tank during construction, pay attention to shake the new tank evenly for 65438±0min, then unscrew the empty tank and replace it as soon as possible to prevent solidification from blocking the spray gun nozzle.

5) Embedding sealant. After filling the construction with foam sealant for 60 min, cut it with a knife, leaving a notch 6 mm deep in the gap around the frame, and then filling the seal with sealant. When filling sealant, the operation should be smooth, and the gun nozzle should always aim at the bottom of the joint with an inclination angle of 45. Always keep the extruded sealant at the front end of the gun nozzle when moving; There is squeezing pressure in the seam, so don't drag the glue away. Avoid leakage or holes; Rubber strip should be straight, streamlined and tidy, with a smooth and beautiful surface.

6) Plastic surgery. Compacting with scraping strips consistent with the joint surface, trimming the glue joint, making the sealant fully contact and penetrate the structural surface, eliminating bubbles and cavities, removing redundant sealant, and forming a smooth, streamlined and tidy sealed joint.

7) Open the drain hole. The lower sill of aluminum alloy window frame should be provided with drainage holes, and its position and number should ensure smooth drainage of the sill in rainy days without water accumulation.

8) Spraying exterior wall waterproofing agent. Spray colorless, transparent and efficient exterior wall waterproofing agent within 30 cm around the window sill of the outer window cover and within 30 cm of the vertical edge of the side of the outer window cover. Seepage prevention treatment.

9) Install the U-shaped aluminum alloy water guide rod. A sealing strip is installed at the upper edge of each window. First, use an impact drill to evenly punch six holes with a depth of 3 cm along the upper edge of the outer window cover, and then hammer the rubber plugs into the holes. At the same time, one-component silicone sealants is coated on the aluminum alloy water diversion strip, and then the aluminum alloy strip is nailed to another from the upper edge of the outer window cover with a screwdriver. Pay attention to filling and sealing the gap between aluminum alloy and exterior wall facing with sealant.

2.3 Strictly control raw materials.

The materials used shall be sampled in strict accordance with the specification requirements, and can be used only after meeting the quality standards and design requirements.

1) The wall thickness of aluminum alloy window profiles used in multi-storey buildings is generally1.0 ~1.2mm; High-rise buildings should not be less than1.2 mm. The gap between windows and walls must be filled with soft materials, and the connection should be elastic. Polyurethane foam caulking agent shall be used as filling material, and neutral silicone sealants shall be used as sealing material.

2) The waterproof sealing materials used shall have material quality certification documents to ensure that the material quality meets the technical requirements; After the waterproof material enters the site, the appearance and quality of the waterproof material should be checked according to various properties of the material. At the same time, the sampling inspection report should be put forward. It can only be used in engineering construction after re-inspection, and unqualified products are strictly prohibited.

2.4 Strengthen quality management

1) to ensure the construction quality of each working procedure, we should start with human management, attach great importance to it ideologically and strictly implement it in action. Implement the overall responsibility of the project manager, the builder and the team are responsible for the system at different levels, clarify the responsibility system at all levels and the reward and punishment system, and improve quality awareness.

2) Implement pre-control quality management, focusing on the detail node structure that is usually easy to miss items and the quality control of the operation process of subdivisional work, and pre-control the quality of main elements such as raw materials, design, construction and management by adopting total quality management method.

3) Before construction, the technical engineer and project leader of the construction unit should organize the construction personnel to learn the relevant specifications, procedures, design and construction drawings, operation methods, technological processes and quality and safety requirements, and focus on the operation essentials of detailed structure construction to ensure high-quality construction.

4) Strictly implement the system of construction handover, inspection, review and acceptance of each working procedure. Without inspection and acceptance or unqualified acceptance, the next working procedure shall not be constructed, and protective measures shall be taken for the completed part to strengthen the protection of finished products. In particular, the water spraying test, to check whether there is any leakage in each process of the external window, can be carried out after the rain or after continuous spraying for 24 hours, or spray water with a high-pressure fire hydrant for 20 minutes three times less than 1m from the external window.