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3Tips to avoid Silicone Weatherpoof Sealant become Cracking

3Tips to avoid Silicone Weatherpoof Sealant become Cracking

Yesterday's "Baiyun Online", had introduced how to identify oil-filled sealant, I wonder if you have already tried it yourself? Is it very fulfilling? You can share the results with "Baiyun Online"! At the same time, we also hope that the products you choose are not filled with oil!
Cracking of silicone weather-proofing sealant is a very troublesome thing. After cracking, it will cause the curtain wall to leak, and even cause a series of problems such as mold on the inner wall. It is very troublesome to follow up.

Aluminum panel curtain wall weather-proof silicone sealant cracking

 

Although the small weathering silicone sealant is a subsidiary material in the cost of the curtain wall, its effect is not to be underestimated! If you want the curtain wall to leak for a long time, it is really sloppy for this little accessory!

Glass curtain wall weathering sealant cracking, weathering sealant mineral oil dissolved hollow glass sealant (butyl sealant)

Water leakage from the curtain wall causes moldy interior walls


So how can we prevent the curtain wall weathering cracking? We believe that three things must be kept in mind: design, material selection and construction!

I.Design

  a) width

Design refers to the design of the sealant joint, including the width and thickness of the sealant joint and the joint movement capacity of the silicone weather-proofing sealant.
The design of the joint width of the curtain wall, in addition to considering the aesthetics, preventing the hard contact of the plate, etc., should also consider the matching of the size of the joint deformation ratio and the resistance of the silicone weather-proofing sealant.
The role of silicone weather-proofing sealant is to meet the deformation of the curtain wall joint. The most important technical index is the "joint movement ability", which means that the silicone weather-proofing sealant can withstand the wide and narrow change of the joint, which is generally expressed by the grading method, such as 25, 35 50, +100/-50, 25 means that the silicone weather-proofing sealant can withstand the gap width of ±25%.
If the joint of the curtain wall is deformed to a large extent and the joint movement capability of the selected silicone weather-proofing sealant is insufficient, cracking of them may occur. The width design of the curtain wall joints can be calculated by referring to the formula recommended in Article 4.3.9 of the JGJ 102 "Technical Specifications for Glass Curtain Wall Engineering".
In addition, the sealant width of the silicone weather-proofing sealant should be not less than 6 mm.
In the actual construction process of the curtain wall, we often encounter some cases where the seam width is smaller than the design width, which is mainly due to the dimensional deviation or installation deviation of the material processing. This narrow sealant joint is most prone to water leakage, because the proportion of joint deformation increases (absolute deformation does not change, the actual seam becomes narrow), and the silicone weather-proofing sealant originally designed for use cannot satisfy the larger deformation.

Some sealant joint is too narrow due to installation deviation

  Baiyun Xiaobian suggestion: When conditions permit, use silicone weather-proofing sealant with higher joint movement capacity, which can effectively reduce the probability of water leakage of the curtain wall, and can extend the service life of silicone weather-proofing sealant, because the actual deformation of silicone weather-proofing sealant does not reach the performance of the product itself. Limit value. Although the initial investment has increased a bit, but the ratio is really small, but the cost of maintenance of the curtain wall is greatly reduced!

b) Depth
To ensure that the silicone weather-proofing sealant does not crack, in addition to the width of the seam, the depth is also very important. Because the aging of weathering sealant usually develops from the surface to the deep layer, if the sealant is too thin, cracking may occur prematurely.

After silicone weather-proofing sealant has deteriorated for more than ten years, cracks appear on the surface. If the thickness is too thin, water leakage may occur.

 

For the depth of silicone weather-proofing sealant, our recommendations are as follows:
a. The depth of silicone weather-proofing sealant should be greater than 6mm;
b. The depth of the silicone weather-proofing sealant should not exceed the width;
c. Insert concrete, masonry or stone joints. When the seam width is less than 13mm, the depth of the silicone weather-proofing sealant is the same. When the seam width is 13-25mm, the depth is half the width;
d. For joints of non-porous materials such as metal and glass, when the slit width is 6.0~13.0mm, the depth of the silicone weather-proofing sealant should be not less than 6.0mm; when the slit width is larger than 13.0mm, the depth of the silicone weather-proofing sealant should be 6.0~13.0 Mm
II. Material selection

A reasonable sealant joint is designed, and the next step is to select the sealant. Selecting sealant mainly depends on two aspects: First, the joint movement capacity of the selected silicone weather-proofing sealant can meet the design requirements, which can be seen from the product packaging; the second is to see if the selected silicone weather-proofing sealant can reach its nominal joint movement capacity, If you do not shoddy it, it will be sent to a third-party testing agency for testing. However, for products with significantly lower prices, you can also use the method recommended yesterday to identify whether there is oil filling.
In addition, for stone curtain wall, we must use special stone sealant or stain-resistant sealant to prevent the sealant from polluting the stone.

III. Construction

Design a reasonable sealant joint, after choosing the right silicone weather-proofing sealant, of course, we must do a good job. For the building, the sealant is actually a “semi-finished product”. Only when it is in the right position, forming the proper shape (width, thickness) and appearance, curing well, and bonding to the substrate, it can finally play its role. Some role. And these must be achieved by the construction process! The quality of the construction process directly affects whether the final curtain wall leaks!
In order to ensure that the sealant and the materials used in the actual project can be well adhered, the adhesion test should be carried out before large-scale construction to ensure that the silicone weather-proofing weather and the material are well bonded.
During the construction process, quality control measures should also be taken. The cured sealant should be tested on site by hand peel adhesion test to check the appearance, curing and bonding of the sealant to ensure the construction quality.

On-site hand peel adhesion test

 

To sum up, if you want silicone weather-proofing sealant to crack, you need to do three things: design, material selection and construction. Only qualified products with reasonable seam design, matching joint movement ability (or higher level), strict construction and strict quality control can ensure that the curtain wall silicone weather-proofing sealant does not crack or leak.
Although the small weathering sealant is a subsidiary material in the cost of the curtain wall, its effect is not to be underestimated! If you want the curtain wall to leak for a long time, it is really sloppy for this little accessory!