Analysis of Causes of Water Seepage in Curtain Wall
Design a: The main force-receiving member aluminum profile column is not set to 20mm expansion joint according to the specification. The thermal expansion and contraction of the aluminum profile and the stress caused by the compression deformation of the main structure will cause the glass to crack and produce water seepage. b: The sealant with a large amount of expansion and contraction was not used in the design, and the necessary calculation was not performed. c: The waterproof sealing treatment of the window is invalid or the number of sealing layers is insufficient (generally two to three seals are required), so that when the rainwater flows along the curtain wall, it directly enters the opening window, and the flooding occurs. d: When the joints are treated with the building, they are not studied and cooperated with the civil works units, but they are constructed separately, and one side of each pipe leads to a seepage channel. In particular, the curtain wall between the top of the curtain wall and the parapet wall is not firmly connected, and the sealing is not strict, forming a water seepage channel.
Aluminum profile a: The surface treatment of the aluminum profile does not conform to the national standard, the adhesion of the surface coating is not strong, and the oxide film is too thin or too thick, resulting in failure of the sealant bond. b: The strength of the aluminum profile column and beam of the main force-receiving member is insufficient, the rigidity is not enough, and the wall thickness of the section subjected to the force is less than 3mm. Under the action of the wind load standard value, the relative deflection is greater than L/180 or the deflection is greater than 20mm, and the curtain wall is serious. Deformation, displacement and rain leakage. c: No high-precision grade aluminum profiles are used (in which the curtain wall columns should adopt ultra-high-precision grade), the aluminum profiles are unqualified, and the bending, twisting, and wavy are seriously exceeded, resulting in the flatness and verticality of the entire curtain wall. The degree cannot meet the requirements.
Sealant a: In order to save cost, the ordinary sealant is used instead of the weather-resistant silicone sealant for outdoor caulking. After the ultraviolet light is irradiated by the sun, the glue seam is prematurely aged and causes cracking. ::Using expired structural silicone sealant, weather-resistant silicone sealant, wall edge glue, foaming, cracking or non-solidification, resulting in water seepage on the curtain wall.
c: The compatibility test of the structural silicone sealant contact material was not carried out according to the specifications. As a result, the structural silicone sealant was incompatible with materials such as aluminum profiles, glass, rubber strips, etc., and chemical changes affecting the adhesion occurred, and the seal was affected. effect.
Glass a: The glass strength is not checked. The glass does not have sufficient bearing capacity. It cracks and breaks under the typhoon and causes water to enter. b: The glass is not checked for thermal stress. The large area of ​​the glass absorbs sunlight, the thermal stress exceeds its allowable stress, causing thermal breakage and leakage of the curtain wall.
c: The dimensional tolerance of the glass exceeds the standard. The amount of intercalation and void of the glass does not meet the design requirements. When the glass is mounted on the glass frame of the bright frame, the glass is too small, the depth of the notch is insufficient, the width of the glue is not up to the requirement, and the glass is easy to The edge is broken; if the glass is too large, the slot is embedded too deep, and the glass is easily expanded by the aluminum profile to cause water seepage. When the glass with inaccurate size is mounted on the hidden frame glass curtain wall, the width of the glue seam is not uniform, and it is difficult to control the quality of the glue injection. According to the regulations, the width of the glass joint wall of the hidden frame glass curtain wall should not be less than 15mm, so as to ensure that the joint gap meets the requirements of the interlayer displacement caused by earthquake and temperature changes, and the glass will not be crushed.
d: The glass is not subjected to edge chamfering and chamfering treatment. When used as a curtain wall material, the glass is prone to stress concentration, resulting in cracking or self-explosion, and there are hidden dangers.
Construction a: When the aluminum frame is installed, it does not operate according to the specifications. The quality is not grasped. The horizontality, verticality, diagonal difference and straightness exceed the standard, which directly affects the physical properties of the curtain wall. b: The construction of weather-resistant silicone sealant is not compact, the sealing is not strict or the aspect ratio does not meet the specifications. c: No attention is paid to the construction conditions of the sealant. There are many rains in the south. For example, in the rainy season, the weather-resistant sealant is forcibly constructed in the open air, and the sealing quality cannot be guaranteed. Structural rubber construction also has certain temperature and humidity conditions, which must be noted. d: The size of the sealing strip does not match or the inferior material is used, and it is quickly loosened or aged, losing the sealing and waterproof function. e: The elastic positioning pad is not used, and the glass is in direct contact with the member.
When the building is deformed or the temperature changes, the component generates a large stress on the glass, often starting to crack the glass from the bottom of the glass.
Use a: No detailed completion data and instructions for use are provided to the user. After the user stays, the user does not understand the use of the curtain wall, causing damage to the curtain wall, collision deformation, pollution, etc., resulting in water seepage. b: When the outer wall is cleaned, improper operation may cause damage to the curtain wall. c: The household arbitrarily carried out the renovation, and the damaged parts were not carefully filled and waterproofed.
Curtain wall seepage prevention measures
There are three basic conditions that cause water seepage and water leakage in the curtain wall: there are pores; there is water; there is a pressure difference with water seepage cracks. Eliminating one or more of these basic conditions is a way to prevent water leakage: one is to minimize the pores; the other is to block the rainwater so as not to wet the gap; the third is to reduce the wind pressure difference at the wetted gap.
a: The design of the curtain wall waterproofing device is first considered in the design. The "equal pressure principle" is used to set the equal pressure chamber and the special pressure introducing hole on the aluminum profile of the curtain wall, so that the internal pressure of the equal pressure chamber is balanced with the external pressure through the special pressure introducing hole. Move the pressure difference to the side of the room that is not exposed to rain. Therefore, there is no difference in wind pressure at the water and there is no water in the part with pressure difference, so as to prevent the external water from being infiltrated into the curtain wall by the pressure difference.
b: Opening a small water outlet hole on the aluminum profile of the curtain wall, collecting the water entering the curtain wall through the small gap and discharging it out of the curtain wall, and discharging a small amount in the equal pressure chamber between the glass, the aluminum profile and the aluminum buckle. Water.
c: It is also conceivable to set up collection pipes and drainage pipes on the glass curtain wall to collect the water that penetrates into the cracks into the interior of the curtain wall, and smoothly discharge through the drainage pipes to a designated drainage hole in the room.
d: Use high-quality structural silicone sealant, weather-resistant silicone sealant, wall edge glue, and strengthen inspection to prevent overdue use. The choice of high-quality float glass, the glass must be treated by the edge, the size error of the glass meets the standard requirements.
e: Pay attention to controlling the use environment of the sealant. It is strictly forbidden to carry out the construction of weather-resistant silicone sealant in the open air on rainy days. The construction workshop of structural glue requires clean and dust-free, the indoor temperature should not be higher than 27 °C, and the relative humidity should not be lower than 50%.
f: Before the silicone sealant, weather-resistant silicone sealant and wall edge glue are injected, the dust, oil stains, loose objects and other dirt on the aluminum frame, glass or gap should be removed first. Fill in the compact, smooth surface, strengthen the maintenance, prevent hand touch, water wash and so on.
g: According to the requirements of the specification, the rain curtain leakage performance inspection should be carried out in layers during the construction of the glass curtain wall in order to repair and control the quality of the curtain wall.
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