Concealed Mullion Curtain Wall System – The Optimal Solution for High-End Architectural Projects

The Concealed Mullion Curtain Wall System has become a prominent trend in modern architecture, especially in high-rise buildings, office towers, and premium commercial complexes. Beyond its sleek and luxurious “glass façade” appearance, this system simultaneously meets key requirements of structural performance, safety, and construction efficiency.

Choosing the right Concealed Mullion Curtain Wall System allows investors and general contractors to ensure superior project quality, enhance architectural aesthetics, and reinforce a sustainable design identity that endures over time.

I. What Is a Concealed Mullion Curtain Wall System?

A Concealed Mullion Curtain Wall System is an advanced façade solution designed to create a continuous, seamless glass surface with minimal visible aluminum profiles. The mullions and transoms are concealed behind the glass, forming a clean and modern aesthetic that defines high-end architecture.

This system is widely applied in Grade-A office buildings, commercial centers, high-rise towers, and luxury hotels, thanks to its perfect balance between visual elegance, engineering precision, and long-term durability. It not only enhances the architectural appeal but also satisfies stringent safety and performance standards required in contemporary façade design.

Concept of “Concealed Mullion”

The term “concealed mullion” refers to a façade design in which all horizontal and vertical aluminum profiles (mullions and transoms) are completely hidden behind the glass surface.

Thanks to this design, the glass façade appears continuous and uninterrupted, without visible aluminum frames dividing the panels — unlike traditional Stick or Semi-unitized systems, where mullions are exposed externally.

Basic Structure of the Concealed Mullion Curtain Wall System

The Concealed Mullion Curtain Wall System is engineered with a focus on aesthetic perfection, structural performance, and safety, making it ideal for premium architectural projects.
It consists of three primary components:

• The structural aluminum framework,

• The glass façade panels, and

• The sealant and gasket system.

Each element plays a critical role in ensuring a seamless appearance, reliable load-bearing capacity, and long-term durability.

Structural Aluminum Framework

Material:Made from high-quality extruded aluminum profiles, imported and surface-treated through anodizing or electrostatic powder coating to provide superior corrosion resistance, oxidation protection, and lasting color stability.

Load-bearing Function:Specially designed for high-rise buildings and commercial complexes, the framework resists strong wind loads, minimizes deformation, and maintains stability over time.

Concealed Mullion Design:The vertical and horizontal mullions are completely concealed behind the glass panels, yet still ensure secure and rigid connections between the glass units. This configuration delivers a smooth, uninterrupted façade that enhances aesthetics while maintaining structural integrity and safety.

Connection Technology:The aluminum framework is assembled using stainless steel bolts, screws, and specialized brackets, ensuring each glass panel is firmly anchored to withstand both static and dynamic loads across the entire façade.

 Glass Façade Panels

Glass Types:The Concealed Mullion Curtain Wall System typically utilizes tempered glass panels ranging from 10–25mm thickness or high-performance Low-E glass, offering excellent impact resistance and vibration control.

Technical Features:

• Thermal Insulation: Reduces heat transfer from outside to inside, improving building energy efficiency.

• Sound Insulation: Minimizes external noise essential for office towers and commercial centers.

• Strength & Safety: Tempered glass combined with structural aluminum ensures outstanding resistance to impact and breakage, enhancing occupant safety.

Architectural Customization:
Architects can select reflective, colored, or decorative printed glass to align with the building’s aesthetic and energy-efficiency requirements, ensuring both visual sophistication and functional optimization.

Specialized Sealant and Gasket System

EPDM / TPV Gaskets

• Ensure airtightness, watertightness, thermal, and acoustic insulation, maintaining the building’s overall energy efficiency.

• Resistant to temperature fluctuations and UV exposure, guaranteeing long-term durability and consistent performance under various weather conditions.

Specialized Silicone Sealant

• Bonds the glass panels to the aluminum framework, creating a secure, flexible connection capable of absorbing vibrations and dynamic loads.

• Enhances the structural stability of the façade, prevents cracking or water leakage, and significantly extends the overall service life of the Concealed Mullion Curtain Wall System.

See more: Tempered Glass Curtain Wall Installation Price

II. Advantages of Using the Concealed Mullion Curtain Wall System in High-End Projects

The Concealed Mullion Curtain Wall System has become a standard façade solution for premium developments — from Grade-A office buildings and commercial centers to landmark high-rise towers.
Beyond its refined, contemporary appearance, this system delivers an ideal balance between aesthetics, engineering precision, and long-term operational performance, meeting the stringent requirements of investors, architects, and general contractors.

Seamless Façade  Enhancing Architectural Value

One of the most distinctive advantages of the Concealed Mullion Curtain Wall System is its continuous, uninterrupted glass surface, free from visible aluminum framing.
With an advanced concealed design, all horizontal and vertical mullions are hidden behind the glass panels, creating a modern, unified, and sophisticated façade.

This solution also allows flexible integration with aluminum-glass doors, sun louver systems, and skylights, resulting in a harmonious architectural composition.
Such seamless aesthetics not only elevate the building’s visual identity but also reinforce its brand value and prestige in the eyes of investors and occupants.

Structural Stability and Load Resistance

The Concealed Mullion Curtain Wall System is constructed from high-grade imported aluminum frames combined with tempered or Low-E glass, offering excellent wind-load resistance, vibration absorption, and long-term stability.
Beyond its visual appeal, the concealed mullion configuration enhances structural integrity, minimizing the risk of warping, misalignment, or glass cracking over time.

This is particularly critical for high-rise and large-scale commercial projects, where safety, durability, and engineering standards are non-negotiable.

Energy Efficiency and Optimized Building Performance

The continuous glass panels of the Concealed Mullion Curtain Wall System maximize natural daylight, reducing the need for artificial lighting.
When combined with Low-E or reflective glass and external shading systems, the façade effectively minimizes solar heat gain, ensuring energy-efficient building operation.

The integrated EPDM/TPV gaskets and high-performance silicone sealant provide superior waterproofing, sound insulation, and thermal resistance, contributing to stable operation, lower maintenance costs, and sustainable long-term performance.

This balance of aesthetic excellence, technical precision, and environmental efficiency makes the Concealed Mullion Curtain Wall System a defining choice for modern, high-end architectural projects.

Long Lifespan and Easy Maintenance

The Concealed Mullion Curtain Wall System delivers exceptional durability through the combination of structural aluminum framing, tempered glass panels, and high-performance gasket and sealant systems.
Its integrated design minimizes the risk of water leakage or gasket failure, significantly reducing maintenance frequency and associated costs.

This system fully complies with the strict technical and performance standards required for large-scale B2B projects, where structural stability, reliability, and longevity are top priorities.

Flexible Application for High-End Projects

The Concealed Mullion Curtain Wall System is highly versatile and can be applied across Grade-A office buildings, luxury hotels, premium commercial centers, and iconic high-rise developments — including those featuring complex curved or non-standard glass façades.

Its ability to integrate seamlessly with aluminum-glass doors, skylight systems, sun louver façades, and Unitized curtain wall modules enables contractors and investors to execute projects with greater precision, efficiency, and reduced construction timelines  while maintaining uncompromised quality.

Implementing the Concealed Mullion Curtain Wall System in high-end architectural projects represents the perfect synergy of aesthetics, engineering, and long-term performance.
It is a façade solution that meets the most demanding B2B standards, enhances architectural value, and ensures durability, stability, and energy efficiency throughout the life cycle of the building.

III. Classification by Aluminum System and Structure

The Stick-type Concealed Mullion Curtain Wall System is installed using a traditional on-site assembly method.
Main aluminum profiles (vertical mullions and horizontal transoms) are fabricated in segments at the factory, then transported to the construction site for manual installation directly onto the building’s structural frame.

Once the aluminum framework is completed, glass panels are mounted externally, fully covering the mullions and transoms to create a continuous and seamless glass façade.

Stick System (Concealed Horizontal or Vertical Mullion Type)

Advantages

• High Flexibility:Allows easy adjustment of module dimensions or adaptation to on-site structural variations during installation.

• Cost Efficiency:Lower initial investment compared to Unitized systems, making it a cost-effective choice for medium- to large-scale projects.

• Adaptability:Ideal for projects where structural tolerances or façade geometry require real-time adjustments during construction.

Limitations

• Extended Installation Time:As assembly occurs entirely on site, construction progress is slower and highly dependent on weather conditions.

• Alignment Accuracy:Manual fitting and glass installation demand skilled workmanship; any misalignment can compromise façade flatness or safety.

• Environmental Exposure:Prolonged outdoor installation may affect the performance of sealants and gaskets if not properly monitored and protected.

Applications

The Stick-type Concealed Mullion Curtain Wall System is commonly used in office buildings, commercial centers, and premium residential complexes of medium to large scale, where modern aesthetics and balanced cost management are key project priorities.

Semi System (Semi-Unitized Curtain Wall)

Structure: The Semi system is a hybrid solution that combines the principles of both Stick and Unitized systems.
Certain components  such as aluminum frames, gaskets, and connection accessories are pre-fabricated at the factory, then transported to the site for final assembly and glass installation.
This approach takes advantage of both the controlled factory environment and the on-site flexibility during installation.

Advantages:

• Balanced cost and quality: More economical than the Unitized system while maintaining high precision thanks to partial factory fabrication.

• Faster installation than Stick: A portion of the work is completed in advance, reducing on-site labor and minimizing disruption.

• Reduced technical risks: Less dependent on weather conditions and worker skill levels compared to the Stick system, ensuring greater stability.

Limitations:

• Moderate installation speed: Faster than Stick, yet not as efficient or synchronized as full Unitized.

• Quality variation: Differences between factory-produced and site-assembled parts may cause minor inconsistencies if not tightly controlled.

Applications: Ideal for large and mid-rise buildings that need to balance budget, timeline, and technical performance, such as shopping malls, hospitals, universities, and office complexes.

Unitized System (Fully Concealed Curtain Wall)

Structure:
The Unitized curtain wall system represents the most advanced façade solution available today.
All modules  including aluminum frames, glass panels, gaskets, and accessories — are fully manufactured and assembled in a factory under strict ISO standards.
These modules are then transported as complete units to the construction site and installed directly onto the structure using specialized anchors, brackets, and bolts, with minimal weather impact.

Advantages:

• Exceptional installation speed: The modular approach allows rapid on-site assembly, significantly shortening overall construction time.

• Consistent quality: Produced under controlled factory conditions, ensuring precision, airtightness, and superior durability.

• Outstanding performance: Excellent resistance to wind load, water infiltration, sound transmission, and thermal transfer, making it ideal for super high-rise and high-spec buildings.

• Premium aesthetics: Delivers a seamless, flat glass surface with a refined, modern appearance — the hallmark of iconic architectural landmarks.

Limitations:

• Higher initial investment: Requires significant upfront costs for manufacturing, logistics, and specialized lifting equipment.

• Strict design accuracy: Once modules are fabricated, on-site adjustments are nearly impossible.

• Logistical constraints: Large modules demand precise transport coordination and heavy-duty equipment, impacting site management.

Applications: The preferred choice for Grade-A office towers, five-star hotels, large-scale commercial complexes, and architectural landmarks that require high precision, superior aesthetics, and fast installation.

Classification by Concealment Type

1. Horizontally Concealed Mullion Curtain Wall System

Structure: In this configuration, the horizontal mullions are completely hidden behind the glass panels, while the vertical mullions remain visible and serve as the primary structural connectors.

Features: The façade forms continuous vertical lines running from top to bottom, visually emphasizing the height of the building and creating an impression of grandeur and stability.

Applications: Ideal for office towers, commercial centers, and high-rise buildings that aim to highlight verticality, strength, and modern aesthetics.

2. Vertically Concealed Mullion Curtain Wall System

Structure:In this type, the vertical mullions are fully concealed behind the glass, while the horizontal transoms remain visible to ensure structural connection.

Features:This layout produces continuous horizontal lines, enhancing the visual width and balance of the façade, making the building appear broader and more proportionate.

Applications:Best suited for wide-frontage structures such as conference centers, commercial complexes, and administrative buildings, where a strong, expansive visual impact is desired.

3. Fully Concealed Mullion Curtain Wall System

Structure:Both horizontal and vertical mullions are completely hidden behind the glass surface, leaving only a flat, seamless glass façade.

Features:Creates the ultimate “glass wall” effect  sleek, elegant, and contemporary with no visible lines, representing refinement and architectural excellence.

Applications:Commonly used in premium projects such as five-star hotels, Grade-A office towers, and large shopping malls, where aesthetic perfection, symbolic value, and distinctive design are the key priorities.

IV. Installation Process and Quality Control

The installation of a Concealed Mullion Curtain Wall System is a highly technical process that requires precise coordination between design, fabrication, transportation, and on-site assembly.
Strict quality control at every stage is essential to ensure the system’s durability, safety, and aesthetic integrity.

• Design phase: Detailed structural and glass-load calculations are performed to ensure system compatibility with the building framework.

• Fabrication phase: Aluminum frames, glass panels, gaskets, and accessories are produced under controlled factory conditions to meet international standards.

• Transportation and installation: Modules or components are carefully handled and assembled on-site, maintaining alignment and airtightness.

• Final inspection: Comprehensive testing of waterproofing, wind resistance, and load-bearing capacity guarantees long-term performance and compliance with façade engineering standards.

Khảo sát và thiết kế kỹ thuật

• Khảo sát hiện trạng: Đo đạc kích thước, xác định tải trọng gió, tải trọng tĩnh và động, các yếu tố môi trường tác động đến công trình.

• Thiết kế chi tiết: Lập bản vẽ kỹ thuật 2D, 3D, mô phỏng khả năng chịu lực, tính toán giải pháp giấu đố tối ưu (ngang, dọc hoặc toàn phần).

• Phê duyệt vật liệu: Lựa chọn hệ nhôm, kính, keo, gioăng đúng tiêu chuẩn quốc tế (ASTM, EN, TCVN) trước khi bước vào sản xuất.

Gia công sản xuất tại nhà máy

• Nhôm định hình: Cắt, gia công CNC chính xác đến từng mm, xử lý bề mặt chống ăn mòn và sơn tĩnh điện theo màu sắc thiết kế.

• Kính: Tôi, cường lực, dán nhiều lớp hoặc phủ Low-E theo yêu cầu chống nóng, cách âm, chống cháy.

• Kiểm soát chất lượng: Kiểm tra module theo tiêu chuẩn ISO 9001, thử nghiệm độ kín khít, độ bền keo silicone, độ đàn hồi gioăng EPDM.

Vận chuyển và lắp đặt tại công trình

Vận chuyển an toàn: Module và kính được đóng gói chuyên dụng, hạn chế va đập, nứt vỡ trong quá trình vận chuyển.

Thi công lắp đặt:

• Dựng khung nhôm đứng và ngang theo thiết kế.
• Cố định kính bằng hệ gioăng, keo silicone chuyên dụng để đảm bảo liên kết chắc chắn và kín khít tuyệt đối.
• Canh chỉnh độ phẳng bề mặt để đạt hiệu ứng giấu đố hoàn hảo.

An toàn lao động: Đảm bảo quy trình an toàn cho thi công trên cao, hệ giàn giáo và thiết bị nâng hạ đạt chuẩn.

Nghiệm thu và kiểm định chất lượng

• Thử kín nước chống gió: Phun nước áp lực cao để kiểm tra khả năng chống thấm; kiểm tra độ rung gió để đánh giá độ ổn định.

• Kiểm tra thẩm mỹ: Đảm bảo bề mặt kính phẳng, đồng bộ màu sắc, không có khe hở, vết bẩn hoặc sai lệch.

• Chứng nhận tiêu chuẩn: Toàn bộ hệ thống vách kính được nghiệm thu theo tiêu chuẩn kỹ thuật và bàn giao cho chủ đầu tư.

 Bảo hành và bảo trì định kỳ

• Bảo hành dài hạn: Hệ nhôm, kính, gioăng, keo silicone thường được bảo hành 3-5 năm.

• Bảo trì định kỳ: Vệ sinh, kiểm tra keo, gioăng, thay thế kịp thời các bộ phận xuống cấp để duy trì tuổi thọ công trình trên 20 năm.

V. Toàn Cầu Invest – Nhà thầu nhôm kính dự án lớn

Đối với các công trình quy mô lớn như trung tâm thương mại, cao ốc văn phòng hay tổ hợp dự án bất động sản, việc lựa chọn nhà thầu nhôm kính uy tín quyết định trực tiếp đến tiến độ, chất lượng và giá trị khai thác lâu dài của công trình. Trong hơn một thập kỷ qua, Toàn Cầu Invest đã khẳng định vị thế là một trong những nhà thầu nhôm kính hàng đầu Việt Nam, chuyên triển khai những hạng mục vách kính mặt dựng giấu đố đòi hỏi kỹ thuật và thẩm mỹ cao.

Năng lực sản xuất và thi công

• Hai nhà máy hiện đại tại Hòa Bình và TP. Hồ Chí Minh, trang bị dây chuyền gia công CNC, sơn tĩnh điện, lắp ráp module đạt chuẩn ISO.

• Đội ngũ kỹ sư và công nhân tay nghề cao, giàu kinh nghiệm trong các dự án cao tầng, phức tạp.

• Khả năng đáp ứng tiến độ nhanh, cung ứng hàng chục nghìn mét vuông nhôm kính cho nhiều công trình cùng lúc.

Giải pháp kỹ thuật chuyên sâu

• Tư vấn lựa chọn hệ Stick, Semi hay Unitized giấu đố phù hợp từng công trình.

• Đảm bảo đồng bộ từ thiết kế, sản xuất đến thi công lắp đặt.

• Ứng dụng các giải pháp nhôm kính tiên tiến: kính Low-E, hộp kính cách âm, kính chống cháy, hệ gioăng, keo silicone chuyên dụng.

Representative Projects

Toàn Cầu Invest has been the trusted façade contractor for numerous large-scale projects across Vietnam spanning commercial centers, luxury resorts, mixed-use urban complexes, and government headquarters.
Each project reflects our deep expertise in design, fabrication, and installation of architectural aluminum and glass systems that meet the highest technical and aesthetic standards.

• The Arena Cam Ranh – One of the largest integrated resort complexes in Khánh Hòa.

• Apec Mandala Wyndham Phú Yên & Apec Diamond Park Lạng Sơn – A chain of international-standard hotels and high-end residences.

• Royal Park Bắc Ninh – A modern urban complex and new architectural landmark of Bắc Ninh City.

• MIPEC Xuân Thủy, Hà Nội – Premium commercial and office center in the heart of the capital.

• Flamingo Hải Tiến, Thanh Hóa – A large-scale beachfront resort complex.

• Ecohome 3, Hà Nội – A model social housing development setting new benchmarks in quality and design.

• Headquarters of Quảng Ninh Provincial Police -A key government building with strict safety and performance standards.

• National Children’s Hospital, Hà Nội – High-spec aluminum and glass façade system for a modern healthcare facility.

• Kepler Land – A flagship mixed-use development with an investment of over VND 2,600 billion.

Commitment to Quality

At Toàn Cầu Invest, quality and precision define every project we deliver.
We provide end-to-end façade solutions from design, engineering, and production to installation and long-term maintenance.

• Full-scope execution: Design  Manufacture Installation  Warranty.

• Warranty policy: 3-5 years of warranty and periodic maintenance to ensure long-term stability and performance.

• Quality control: All processes strictly follow international standards such as ASTM, EN, and TCVN, under a comprehensive ISO-based management system.

With over a decade of experience and a track record of collaboration with top investors, general contractors, and architects,
Toàn Cầu Invest stands as a trusted partner in delivering façade excellence for national-scale developments.

If you are looking for a professional façade contractor with in-house manufacturing, experienced engineering teams, and proven project capability,
 Toàn Cầu Invest is your reliable choice for total aluminum and glass solutions.

• Hotline: 0902 50 1185 – 0902.168.238

• Website: www.toancauinvest.vn

• Văn phòng: LK 12 – 31 Khu đô thị mới Văn Khê, P. La Khê, Q. Hà Đông, Hà Nội.