Framed-type Glass Curtain Wall

Introduction to Framed-type Glass Curtain Wall

A framed-type glass curtain wall is a non-structural, external building facade that is primarily made of glass and supported by an aluminum or steel frame. Unlike traditional walls, which support the weight of the building, curtain walls are designed to withstand environmental forces such as wind and seismic loads while providing natural light and panoramic views.

Components of a Framed-type Glass Curtain Wall

Frame Materials: Aluminum and steel are the most common materials used for framing glass curtain walls due to their strength, durability, and lightweight properties.

Glass Panels: The glass used in curtain walls is typically tempered or laminated for safety and can be tinted or coated to improve energy efficiency.

Sealants and Gaskets: Sealants and gaskets are used to weatherproof the joints between the glass panels and the frame, preventing water infiltration.

Thermal Breaks: Thermal breaks are insulating materials inserted between the inner and outer frames to reduce heat transfer and improve energy efficiency.

How many types of framed type glass curtain walls?

From the external form of the curtain wall, it includes:

Exposed frame glass curtain wall
Semi-hidden frame glass curtain wall
Hidden frame glass curtain wall

Divided by the installation method, it has
Unitized curtain walls
Stick system curtain walls

1. Exposed frame glass curtain wall

The exposed frame glass curtain wall features fixed glass panels with horizontal and vertical metal frames visible on the exterior surface. While the original profiles were initially functional and square in shape, manufacturers have innovated various cross-sectional designs that serve both functional and decorative purposes. These metal frames can vary significantly in form, thanks to the diversity of metal materials, colors, and surface finishing techniques available.

2. Semi-hidden frame curtain wall

A semi-hidden frame curtain wall is a type of structural glazing system used in building facades. In this system, the glass panels are bonded to metal frames using structural adhesive in a factory setting, creating small plate units. These units are then transported to the construction site, where they are suspended and fixed onto the metal supporting structure. The structural adhesive not only bonds the glass to the frame but also plays a crucial role in resisting horizontal wind loads and supporting the weight of the glass panels.

In a semi-hidden frame curtain wall, one direction of the metal frame is exposed on the outer surface, while the other direction is bonded with structural adhesive. This combination of metal profiles and structural sealant ensures that the glass panels are securely fixed in place, providing both structural integrity and a sleek, modern appearance.

3. Hidden frame curtain wall

A hidden frame curtain wall is a type of curtain wall system where the glass panels are bonded to the structure entirely using adhesive, without any visible metal framing on the exterior. This means that all four sides of the glass are bonded to the structure, and from the outside, only the glass and the glue joints are visible. The metal frame, if present, is located behind the glass panel, making the appearance of this type of curtain wall very clean and minimalistic.

This design approach gives the curtain wall a sleek and uncluttered look, with no visible metal framing or unnecessary details. The use of structural adhesive to bond the glass panels also helps to create a seamless and uniform appearance, enhancing the overall aesthetics of the building facade.

In the past, structural glue-bonded curtain walls often used high-reflectivity coated glass, resulting in simple block-like appearances that could look dull and create light pollution over time. However, modern architects now prefer high transparency and low reflectivity glass to provide a more visually appealing experience.

The hidden frame curtain wall, which relies on structural glue to fix the glass, has stringent requirements for structural sealant. Its durability is crucial for the safety of the curtain wall, necessitating the selection of qualified structural glue (with the manufacturer’s quality assurance certificate) and a high-level construction team. Silicone structural adhesive, with a history of about 40 years, generally comes with a 10-year warranty for legal reasons, but its actual lifespan should be 30-50 years. Some countries, like Germany, have strict regulations for glue-bonded glass curtain walls, requiring additional mechanical fixation for parts below 8m above the ground if they exceed this range.

4. Two sides fixed frame glass curtain wall

A two sides fixed frame glass curtain wall is a type of curtain wall system where the glass panels are fixed to the building structure on two sides, typically the top and bottom or left and right edges. This type of curtain wall is characterized by its sleek and modern appearance, with minimal visible framing and a focus on showcasing the glass panels. Its main purpose is to provide a lightweight and aesthetically pleasing enclosure for buildings, allowing natural light to enter while maintaining thermal and weather performance.

5. Stick System Curtain Wall

A Stick System Curtain Wall is a type of curtain wall system used in building construction. It consists of vertical and horizontal members (sticks) that are assembled and installed piece by piece on the building facade. This system allows for the integration of various materials such as glass, metal panels, or stone, offering design flexibility and aesthetic appeal. Its main features include easy installation, customization options, and the ability to accommodate thermal expansion and contraction. The primary function of a Stick System Curtain Wall is to provide a non-structural exterior envelope that protects the building from weather elements while allowing natural light to enter and providing a visually pleasing exterior appearance.

6. Unitized curtain wall

A unitized curtain wall is a type of curtain wall system used in buildings. It is composed of large units that are pre-assembled and glazed in a factory, then shipped to the construction site for installation. This approach allows for faster and more efficient installation compared to traditional stick-built curtain walls, where components are assembled on site. Unitized curtain walls are often used in high-rise buildings and offer benefits such as improved quality control, reduced on-site labor, and potentially lower installation costs.

The visual impact of exposed-frame glass curtain walls doesn't vary significantly between unitized and component types. However, the difference is substantial for fully hidden-frame glass curtain walls. Unitized curtain walls typically use a plug-in method, resulting in concave joints for hidden-frame curtain walls. This leads to a more refined appearance with straighter lines.

Framed-type Glass Curtain Wall


Are glass curtain walls suitable for all types of buildings?

Glass curtain walls are suitable for a wide range of buildings, but the design and installation must be carefully considered to ensure structural integrity and energy efficiency.

How long do glass curtain walls last?

With proper maintenance, glass curtain walls can last for decades, providing long-term benefits in terms of aesthetics and energy efficiency.

Can glass curtain walls be recycled?

Yes, glass curtain walls can be recycled, making them a sustainable building material choice.

Do glass curtain walls require special cleaning?

Glass curtain walls should be cleaned regularly using mild detergent and water to maintain their appearance and performance.

Are glass curtain walls energy-efficient?

Yes, properly designed and installed glass curtain walls can improve the energy efficiency of a building by reducing the need for artificial lighting and heating.

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