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Views: 0 Author: Site Editor Publish Time: 2026-02-28 Origin: Site
In curtain wall construction and façade engineering, two types of sealants are commonly used: structural sealant and weatherproof sealant. Although both are widely applied in glass curtain walls and building joints, their performance, purpose, and load-bearing capacity are fundamentally different.
Understanding the difference between structural sealant and weatherproof sealant is critical for ensuring building safety, durability, and long-term performance.
Structural sealant, often referred to as structural silicone sealant, is a high-strength adhesive designed to bond structural components. It is capable of bearing significant loads and maintaining long-term stability under environmental stress.
Typical performance characteristics include:
Compressive strength above 65 MPa
Steel-to-steel tensile bonding strength above 30 MPa
Shear strength above 18 MPa
Excellent resistance to aging, fatigue, and corrosion
Structural sealants are engineered to provide stable performance throughout the designed service life of a building. Because they directly influence façade safety, most structural sealants used in curtain wall systems are silicone-based.
Structural silicone sealant offers several important benefits in modern construction:
It features neutral curing, making it compatible with most building materials without causing corrosion or adverse reactions. It provides extremely strong adhesion to glass, metal, and other substrates, often without the need for primer under proper conditions.
After curing, structural sealant exhibits high modulus properties and can typically accommodate ±25% joint movement while maintaining load-bearing capacity. It also demonstrates outstanding resistance to aging and environmental exposure.
Under standard conditions of 20–25°C, structural sealant generally requires 24 hours to cure before use. Accelerated curing can be achieved through controlled heating, such as 2 hours at room temperature followed by 2 hours at 80°C.
In colder environments, curing time must be extended or assisted with heating to ensure proper performance.
Structural sealant is primarily used for structural bonding rather than simple sealing. It can partially replace traditional mechanical fastening methods such as welding, riveting, or bolting.
In curtain wall systems, structural silicone sealant is used to:
Bond glass panels to metal frames
Create fully hidden or semi-hidden frame curtain wall systems
Perform structural bonding in insulating glass units
Beyond curtain walls, structural adhesives are widely applied in reinforcement and repair engineering, including steel plate bonding, carbon fiber bonding, crack strengthening, anchoring, concrete bonding, and structural repair.
Weatherproof sealant, often called silicone weather sealant, is a single-component, neutral-curing silicone sealant specifically designed for weather sealing applications.
Unlike structural sealant, weatherproof sealant is not intended to bear structural loads. Its primary function is to provide durable sealing against water, air, and environmental exposure.
When applied, the sealant is extruded into joints using a caulking gun. It cures by absorbing moisture from the air at room temperature, forming a flexible elastomer that effectively seals building joints.
Weatherproof sealant is valued for its flexibility and resistance to extreme environmental conditions.
It offers excellent UV resistance, resistance to acid rain, ozone, moisture, and long-term outdoor exposure. After curing, it maintains elasticity in temperatures as low as -30°C and as high as +90°C without cracking, hardening, or degrading.
Its movement capability typically reaches Class 20, allowing it to accommodate normal expansion and shear deformation in curtain wall joints.
Neutral curing ensures it does not corrode materials such as coated glass, aluminum panels, concrete, marble, or granite. In most cases, primer is not required.
Weatherproof sealant is widely used for:
Weather sealing of glass curtain walls
Sealing aluminum panel and enamel curtain walls
Joint sealing between concrete and metal
Roof construction joint sealing
Its function is focused on waterproofing and air sealing rather than structural bonding.
The most important distinction lies in load-bearing capacity. Structural sealant is designed for structural bonding and can safely transfer loads between materials. Weatherproof sealant is used primarily for joint filling and environmental sealing.
Structural sealant is applied in areas where structural strength is required, such as bonding glass to metal frames. Weatherproof sealant is used at external joints to prevent water penetration and air leakage.
While weatherproof sealant offers strong adhesion and superior weather resistance, structural silicone sealant provides significantly higher tensile strength, tear resistance, modulus, and overall mechanical performance.
Structural sealant generally has higher hardness, higher strength, and higher cost compared to weatherproof sealant of the same grade.
Structural sealant and weatherproof sealant both provide excellent weather resistance, especially when silicone-based. However, their roles in construction are fundamentally different.
Structural silicone sealant directly impacts building safety. If it fails, serious structural consequences may occur. For this reason, most structural sealants are silicone-based and formulated for long-term durability in natural environments.
Weatherproof sealant does not carry structural responsibility. If failure occurs, the typical result is water leakage or air infiltration rather than structural collapse. Therefore, weatherproof sealants may be made from various materials, including polyurethane, polysulfide, acrylic, and silicone. Among these, silicone generally provides the best weather resistance.
Choosing the correct sealant type based on function ensures safety, durability, and optimal performance in curtain wall and façade applications.
